Cytological aspects of rat mammary cancer therapy with soluble tumor-associated antigens and anticancer drugs

Some cytological aspects of rat mammary cancer therapy with soluble tumor-associated antigens (sTAA- p66 and p51) and the anticancer drug cyclophosphamide (CPA) are analyzed. Vaccination with sTAA results in a significant increase in the areas related to the production of T and B cells in the white pulp (germinal center and PALS) and in the marginal zone of the spleen. sTAA stimulate the production of CD8+ lymphocytes inside the tumors and in bone marrow, and of CD8+ thymocytes in the medulla of the thymus. Treatment of rats with CPA decreases the activity of lymph cells in tumors, especially of CD4+ lymphocytes. In the spleen, CPA decreases the size of areas related to the production of B and T cells. In the bone marrow, CPA affects the process of myelogenesis and causes significant substitution of cellular components with fatty tissue. The combined treatment with CPA and sTAA increases the number of lymph cells and the apoptotic index in tumors, and restored the rate of B cells producing in the spleen. Similar effect was observed in lymph nodes with accumulation of B lymphocytes in the primary and secondary follicles, and of T lymphocytes in the paracortical zone. In the thymus, CPA alone or in combination with sTAA repairs the inhibitor effect of a carcinogen on synthesis of CD4+ and CD8+ thymocytes. In combined using with CPA, sTAA activate the B- and T-lymphocyte production in the host's immune system and decrease the toxic side-effects of a drug.

Local and systemic activity of the polysaccharide chitosan at lymphoid tissues after oral administration

Chitosan is a cationic polysaccharide derived from the partial deacetylation of chitin, which exhibits particular properties: interacts with negatively charged sites on the cell surface; changes the permeability of intestinal epithelium, enhancing the uptake of peptides and proteins; and activates leukocytes. Antigens coadministered or encapsulated with the polysaccharide show improved mucosal and systemic humoral immune responses, although the mechanism is poorly understood. Herein, we characterized in Peyer's patches mesenteric lymph nodes and spleen molecular events triggered after oral administration of chitosan in the absence of protein antigen. Sixteen hours after feeding, we studied the uptake and distribution of the polysaccharide, the phenotype of recruited antigen-presenting cells (APC), the induction of cytokines such as tumor necrosis factor alpha, interleukin (IL)-12, IL-4, IL-10, and transforming growth factor-beta (TGF-beta), and the activation of T lymphocytes. We show here that the uptake of chitosan at inductive mucosal sites involves CD11b/c+ APC and that chitosan feeding increases the percentage of OX62+ dendritic cells, which up-regulate the major histocompatibility complex class II antigens without changing the expression of costimulatory CD80 or CD86 molecules. The polysaccharide elicits the release of IL-10 as well as the expression of IL-4 and TGF-beta in mucosa, and in spleen, the activation of CD3+ T cells occurs. Our results demonstrate that chitosan acts by enhancing the T helper cell type 2 (Th2)/Th3 microenvironment in the mucosa. A single dose of this polysaccharide exhibits local and systemic effects, and its activity could be relevant in the maintenance of the intestinal homeostasis.

Early antiretroviral therapy for simian immunodeficiency virus infection leads to mucosal CD4+ T-cell restoration and enhanced gene expression regulating mucosal repair and regeneration

Simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections lead to rapid depletion of CD4(+) T cells from gut-associated lymphoid tissue (GALT). Although the administration of antiretroviral therapy (ART) has been shown to increase CD4(+) T-cell levels in the peripheral blood in both SIV and HIV infections, its efficacy in restoring intestinal mucosal CD4(+) T cells has not been well investigated. To gain insights into the molecular mechanisms of virally induced disruptions in the mucosal immune system, we have evaluated longitudinal changes in viral burden, T-cell subsets, and mucosal gene expression profiles in SIV-infected rhesus macaques in the absence or presence of ART. Our results demonstrate a dramatic suppression of mucosal viral loads and rapid reconstitution of CD4(+) T cells in GALT in animals receiving ART that were not observed in untreated SIV-infected animals. DNA microarray-based gene expression profiling indicated that CD4(+) T-cell restoration in GALT was associated with up regulation of growth factors and genes involved in repair and regeneration of the mucosal epithelium. In contrast, untreated SIV-infected animals increased expression of lymphocyte activation and inflammatory response-associated genes and did not up regulate mucosal growth and repair associated transcription. In conclusion, these data indicate that initiating ART in primary SIV infection may lead to the restoration of the mucosal immune system through reduction of inflammation and promotion of epithelial repair in the intestinal mucosa.

L-arginine-enriched parenteral nutrition affects lymphocyte phenotypes of gut-associated lymphoid tissue

BACKGROUND

Experimentally, total parenteral nutrition (TPN) diminishes gut-associated lymphoid tissue (GALT) cell numbers and function. Although glutamine supplementation is known to reverse TPN-induced changes in GALT, effects of another conditionally essential amino acid, L-arginine (ARG), on GALT remain unclear.

METHODS

Twenty-two male Institute of Cancer Research mice were randomized to standard TPN (0.3% arginine, STD-total parenteral nutrition) or 1% ARG-enriched TPN (ARG-total parenteral nutrition). After 5 days of feeding, lymphocytes were harvested from Peyer's patches (PP), the lamina propria, and intraepithelial (IE) spaces of the small intestine to determine cell yields. Lymphocyte phenotypes (alphabetaTCR, gammadeltaTCR, CD4, CD8, and B220 as a B cell marker) were determined using flow cytometry. IgA levels in washings of the small intestine, upper respiratory tract, and lungs were measured with ELISA.

RESULTS

ARG-total parenteral nutrition did not affect lymphocyte yields. The percentages of CD4+ cells in PP and IE, and alphabetaTCR+ cells in PP, were significantly higher in the ARG-total parenteral nutrition than in the STD-total parenteral nutrition mice, without marked differences in other phenotypes examined. There were no significant differences in intestinal and respiratory tract IgA levels between the 2 groups of mice.

CONCLUSIONS

One percent ARG supplementation of TPN does not improve GALT cell number or mucosal IgA level but benefits to increase CD4+ cell percentages in GALT.

Effects of Feeding Vitamin A and Lactoferrin on Epithelium of Lymphoid Tissues of Intestine of Neonatal Calves

Circulating levels of vitamin A (retinol) and lactoferrin (Lf) are low in calves at birth. Bovine colostrum contains relatively high amounts of vitamin A and Lf, and both substances are intestinally absorbed by neonatal calves. There is evidence that these compounds interact with insulin-like growth factor binding proteins and thus influence the status and effects of insulin-like growth factor. The hypothesis was therefore tested that vitamin A and Lf influence epithelial growth, development, and absorptive capacity of the small and large intestine and modulate intestinal immune tissues (Peyer's patches; PP). Four groups of calves (n = 7 per group) were fed a milk-based formula with or without vitamin A and (or) Lf. Group F received formula (F) only; group F(A) was fed F supplemented with vitamin A; group F(L) was fed F supplemented with Lf, and group F(AL) received F plus vitamin A plus Lf. An additional group of calves (group C; n = 7) served as positive control and was fed colostrum (C) from pooled milk obtained on d 1, 2, and 3 of lactation. Amounts of nutritive components in formula and colostrum were similar. Blood samples were taken to measure vitamin A and Lf, and plasma xylose (added on d 4 to feeds) was measured postprandially for 8 h as a marker of intestinal absorptive capacity. Plasma vitamin A was low at birth and further decreased in groups F and F(L), but increased in groups F(A), F(AL), and C. Plasma Lf was low at birth and transiently increased up to 4 h after the first meal in group C. Xylose absorption was higher in group C than in other groups. Incorporation of 5-bromo-2'-deoxyuridine into DNA (as a measure of cell proliferation rate) was enhanced in intestinal crypts in groups F and F(L) at all intestinal sites. Ileum villus heights of groups F and F(L) were smaller than of groups F(A) and F(AL). Villus height to crypt depth ratios were smaller in F-fed groups (especially in groups F and F(L)) than in C-fed calves in the duodenum and jejunum. Incorporation of 5-bromo-2'-deoxyuridine into colon crypt cells of group F was greater than in groups F(L) and F(A). Sizes of follicles of PP in the ileum were greater in group F(A) than in group F. In the ileum, vitamin A and Lf tended to interact with PP size. In conclusion, feed supplementation of vitamin A and Lf influenced growth of the ileum and colon. Interactions were observed between vitamin A and Lf on epithelial cell maturation, villus growth, and size of follicles in PP of neonatal calves.

Inhibition of IL-18 reduces myeloperoxidase activity and prevents edema in intestine following alcohol and burn injury

Previous studies have shown that alcohol (EtOH) ingestion before burn injury impaired intestinal barrier and immune function. This study determined whether EtOH and burn injury up-regulate interleukin (IL)-18 and whether IL-18 up-regulation following EtOH and burn injury is a cause for neutrophil recruitment and increased intestinal edema. Rats (250 g) were gavaged with EtOH to achieve a blood EtOH level in the range of 100 mg/dL prior to burn or sham injury (25% total body surface area). A group of rats was treated with Ac-YVAD-CHO (5 mg/kg), an inhibitor of caspase-1 (an enzyme that converts pro-IL-18, an inactive form of IL-18, to mature IL-18), at the time of injury. One day after injury, rats were killed. IL-18 production was determined in circulation and in the supernatants harvested from spleen, mesenteric lymph nodes, and Peyer's patch cell cultures as well as in intestinal tissue homogenates. Neutrophil accumulation in intestine was determined by measuring myeloperoxidase (MPO) activity. We found a significant increase in IL-18 levels in the lymphoid cell supernatants and intestinal tissue homogenates obtained from EtOH and burn-injured rats compared with the rats receiving burn or sham injury. This was accompanied by an increase in intestinal MPO and edema. No demonstrable change in intestinal morphology was observed in any group. Treatment of rats with caspase-1 inhibitor significantly attenuated the increase in IL-18 levels and intestinal MPO activity in EtOH and burn-injured rats. Inhibition of IL-18 also prevented an increase in intestinal tissue water content. As MPO is considered an index of neutrophil infiltration, results presented in this manuscript collectively suggest that IL-18 up-regulation is likely to contribute to the increased neutrophil infiltration and edema in intestinal tissue observed following EtOH and burn injury.

Effects of diclofenac, piroxicam and alpha-tocopherol on monoaminelymphopoietic interfacing in mice

The non-steroidal anti-inflammatory drugs (NSAIDs) diclofenac (CAS 15307-79-6) and piroxicam (CAS 36322-90-4) were shown in previous works to induce bone marrow lymphopoiesis. The present work aimed at evaluating the extent to which lymphopoietic effects of the above mentioned drugs as well as their interactions with alpha-tocopherol (CAS 10191-41-0) may be reflected in changes in the tissue levels of norepinephrine (NE), dopamine (DA) and serotonin (5-HT). The study was performed in male adult mice. The doses were given once daily for 7 days. The evaluations were performed in 2 phases. First, dose-response relationships of each of diclofenac, piroxicam and alpha-tocopherol were evaluated using bone marrow lymphocytes counts and monoamines levels in plasma, brain and spleen. Then, interactions of alpha-tocopherol (10 mg/kg) with diclofenac (20 mg/kg) and piroxicam (3 mg/kg), respectively, were evaluated. The interaction evaluations included effects on bone marrow lymphocytes count, monoamines levels in plasma, brain, spleen and thymus, as well as spleen weight. The obtained findings revealed that diclofenac, piroxicam and alpha-tocopherol decreased NE and DA levels in plasma, brain and spleen. There was some correlation between the decrease in plasma NE and the bone marrow lymphopoiesis. Pre-administration of alpha-tocopherol failed to maintain monoamines levels at the range of normal values in plasma, brain and spleen of NSAIDs-treated mice except splenic DA levels. In addition, the decrease in NE level induced by administration of piroxicam or diclofenac, either alone or together with a-tocopherol, corresponded to the increase in bone marrow lymphopoiesis. The present work suggests that the diclofenac- and piroxicam-induced bone marrow lymphopolesis as well as their respective interactions with alpha-tocopherol are associated with parallel changes in monoamines levels, especially those of NE and 5-HT.

Isoleucine needs of thirty- to forty-day-old female chickens: immunity

Broilers fed diets with reduced amino acid levels may be limiting in isoleucine. Because research addressing daily Ile needs for broiler immunity is sparse, Ile responses for immunity in female broilers were evaluated in 2 experiments in broilers from 30 to 42 d of age. Cellular and humoral immunity were evaluated in diets limiting in Ile and diets varying in Ile from deficient to adequate. Pen was the experimental unit in both experiments. Treatments in experiment 1 consisted of 2 levels of Ile (0.42 vs. 0.72% total of diet) and 3 strains of broilers, Arbor Acres+, Ross 508, Ross 708 (6 treatments; 5 pens each). In experiment 1, measurements consisted of: a cutaneous basophil hypersensitivity test to phytohemagglutinin-P (PHA-P) on d 37 and 38; cell quantification of CD4+, CD8+, and BU-1+ lymphocytes at d 41 and 42; and relative immune organ weights at 42 d. No Ile x strain interaction occurred. Feeding an Ile-deficient diet to broilers suppressed the cell mediated response to PHA-P, and reduced thymus weight and the percentage of CD8+ T cells. There were no significant differences between strains. In experiment 2, gradations of Ile (0.42, 0.50, 0.58, 0.66, 0.74, and 0.82% total of diet) were fed to one strain (Ross 508) of female broilers (7 pens per diet). A control diet containing 0.70% Ile (6 pens) was compared with an Ile surfeit concentration. Measurements in experiment 2 consisted of a hypersensitivity test to PHA-P on d 35 and 36; a primary antibody response to SRBC from 35 to 42 d; cell quantification of CD8+ alpha, beta, and T cell receptor (TCR)-1 (delta/gamma) lymphocytes on d 41 and 42; and immune organ weights at 42 d. Immunity measurements in birds fed surfeit Ile in the titration diets were equal to birds fed the control diet. A linear response to increasing Ile was obtained for relative bursa, but no Ile quadratic responses were noted for other measurements in experiment 2. Although feeding broilers a diet deficient in Ile suppressed some immune criteria, it does not appear that a marginal Ile deficiency will compromise immunity in growing female broilers.

[Effect of anthracyclines on the intestine and its lymphoid organs (literature review)]

Anthracycline drugs after their administration first of all affect the cells with active proliferation and differentiation resulting not only in inhibition of the processes but also in induction of apoptosis, that precisely explains the pathological shifts in the intestinal epithelium, i.e. in the tissue with many dividing and maturating cells. The damaged epithelium after the use of anthracycline drugs becomes permeable for many substance of the antigenic nature from the intestine lumen that stimulate the response of the lymphoid organs.

Omental milky spots and peritoneal dialysis--review and personal experience

BACKGROUND

Little research has been dedicated to milky spots (MS), except for their role in oncology. In the field of peritoneal dialysis (PD), studying MS could help in understanding peritoneal defenses.

METHODS

We reviewed the methods for detecting and counting omental MS and studied modifications induced by chemical and inflammatory stimuli. The reactions of MS to peritoneal catheters, PD solutions, and infection were studied in 32 rabbits. We also evaluated changes in MS in 39 serial omental biopsies from 16 patients with different histories of PD, and examined peritoneal biopsies from 38 patients with sclerosing peritonitis.

RESULTS

The catheter provoked an immediate increase in the number and size of MS in rabbits. Intraperitoneal infusion of commercial PD solution containing 1.38% or 3.86% glucose for 30 days led to a slight but significant increase in the number and size of MS, without differences between the two glucose concentrations. Peritonitis caused a sharp increase in the number of MS in rabbits and humans, and a particular transformation. In patients with simple sclerosis, we observed normal MS having the same number and size as in patients without simple sclerosis. A few MS were found in only 2 patients with sclerosing peritonitis.

CONCLUSIONS

Peritoneal dialysis activates omental MS. Peritoneal infection leads to a marked increase in the activity of MS, some of which undergo a singular transformation, casting doubt on previous theories about differentiation of MS from other lymphatic organs. Comparison with oncological studies indicates certain contact points. The presence of MS in PD patients with simple sclerosis is in contradiction to other morphological studies sustaining that MS act only when in contact with a fenestrated mesothelial basement membrane. Finally, the shortage of MS in patients with sclerosing peritonitis raises certain questions about etiopathogenesis.

The Mycoplasma-derived macrophage-activating 2-kilodalton lipopeptide triggers global immune activation on nasal mucosa-associated lymphoid tissues

A better knowledge on how immune responses are initiated in mucosal tissues would facilitate the design of new mucosal vaccines, as well as improve our understanding on host defense against infection. We investigated the mechanisms of adjuvanticity of the Mycoplasma-derived macrophage-activating 2-kDa lipopeptide (MALP-2), which binds to the heterodimer formed by the Toll-like receptors 2 and 6 (TLR2 and -6), at the level of the murine nasal mucosa-associated lymphoid tissues (NALT). TLR2 expression analysis demonstrated that several cell types from the nasal cavity were able to overexpress this receptor, either constitutively (such as B cells) or after stimulation (i.e., T cells). MALP-2 stimulated a strong B-cell activation. In addition, the antigen presentation capacity of dendritic cells was improved after in vivo loading with antigen in the presence of MALP-2. We also observed an up-regulated expression of activation markers and adhesion molecules on T cells, suggesting that they have enhanced responsiveness and interaction potential. Quantitative reverse transcription-PCR analysis showed that MALP-2 administration resulted in the stimulation of a proinflammatory cascade. We observed an early up-regulated expression of IP-10, MCP-1, MCP-3, MIP-1alpha, MIP-2, and CCR-2 which was reversed within 36 h. The obtained results demonstrated that MALP-2 creates a reversible local microenvironment which promotes effective priming of T and B cells in the NALT.

Depletion of CD4 T lymphocytes in human lymphoid tissue infected ex vivo with doxycycline-dependent HIV-1

We investigated whether CD4+ T cells that do not produce HIV-1 are killed in HIV-infected human lymphoid tissue. Tissue blocks were inoculated with high amount of doxycycline-dependent HIV-rtTA. Doxycycline triggered productive infection and loss of CD4+ T cells in these tissues, whereas without doxycycline, neither productive infection nor CD4+ T cell depletion was detected in spite of the massive presence of virions in the tissue and of viral DNA in the cells. Thus, HIV-1 alone is sufficient to deplete productively infected CD4+ T cells but is not sufficient to cause the death of uninfected or latently infected CD4+ T cells.

Effects of FTY720 on rat lymphoid organs

INTRODUCTION

In this study, we examined the in vivo effect of FTY720 on rat thymus and spleen.

MATERIALS AND METHODS

Inbred male Lewis (RT-I(l)) rats, 5-weeks-old, received FTY720 (0.1, 1, or 10 mg/kg) by intramuscular injection into 1 of 4 limbs daily for 7 days. The rats were humanely killed at 1, 3, 5, or 7 days after starting administration of FTY720. The thymus and spleen were obtained for hematoxylin and eosin (HE) as well as immunoperoxidase staining using the antibodies OX8 (CD8), W3/25 (CD4), and OX6 (major histocompatibility complex class II).

RESULTS

HE staining revealed marked atrophy in the cortical region of the thymus among rats administered FTY720 at the dose of 10 mg/kg. The atrophy extended to the whole cortex. On day 7 of administration of FTY 720 (10 mg/kg), the medulla of the thymus showed relative expansion due to cells accumulation. Also, the spleens of FTY720-treated rats revealed an obvious reduction in the T-cell-dependent areas around the central artery. In conclusion, the immunosuppressive effect of FTY720 may be due to an inhibitory effect on T-cell emigration from the thymus to the periphery.

Inhalation toxicity of brevetoxin 3 in rats exposed for 5 days

Brevetoxins are potent neurotoxins produced by the marine dinoflagellate Karenia brevis. Exposure to brevetoxins may occur during a K. brevis red tide when the compounds become aerosolized by wind and surf. This study assesses possible adverse health effects associated with short-term inhalation exposure to brevetoxin 3. Male F344/Crl/Br rats were exposed to 500 microg brevetoxin 3/m3 by nose-only inhalation for 0.5 or 2 h/d for 5 consecutive days. Control rats were sham exposed for 2 h to vehicle. Calculated deposited brevetoxin doses were 8.3 and 33 microg/kg/d for the low- and high-dose groups, respectively. At the termination of exposures, only body weights of the high-dose group (Group B) were significantly below control values. By immunohistochemistry (IHC), small numbers of splenic and peribronchiolar lymphoid tissue macrophages stained positive for brevetoxin, while nasal mucosa, liver, and brain were IHC negative for brevetoxin. No gross or microscopic lesions were observed in any tissue examined. There was no biochemical evidence of cytotoxicity or inflammation in bronchoalveolar lavage fluid. Alveolar macrophages showed some evidence of activation following brevetoxin exposure. Humoral-mediated immunity was suppressed in brevetoxin-exposed rats as indicated by a >70% reduction in splenic plaque-forming cells in brevetoxin-exposed animals compared to controls. Results suggest that the immune system may be a target of toxicity following brevetoxin inhalation. Future studies will focus on identification of a no-effect level and mechanisms underlying brevetoxin-induced immune suppression.

Mechanism by which orally administered beta-1,3-glucans enhance the tumoricidal activity of antitumor monoclonal antibodies in murine tumor models

Antitumor mAb bind to tumors and activate complement, coating tumors with iC3b. Intravenously administered yeast beta-1,3;1,6-glucan functions as an adjuvant for antitumor mAb by priming the inactivated C3b (iC3b) receptors (CR3; CD11b/CD18) of circulating granulocytes, enabling CR3 to trigger cytotoxicity of iC3b-coated tumors. Recent data indicated that barley beta-1,3;1,4-glucan given orally similarly potentiated the activity of antitumor mAb, leading to enhanced tumor regression and survival. This investigation showed that orally administered yeast beta-1,3;1,6-glucan functioned similarly to barley beta-1,3;1,4-glucan with antitumor mAb. With both oral beta-1,3-glucans, a requirement for iC3b on tumors and CR3 on granulocytes was confirmed by demonstrating therapeutic failures in mice deficient in C3 or CR3. Barley and yeast beta-1,3-glucan were labeled with fluorescein to track their oral uptake and processing in vivo. Orally administered beta-1,3-glucans were taken up by macrophages that transported them to spleen, lymph nodes, and bone marrow. Within the bone marrow, the macrophages degraded the large beta-1,3-glucans into smaller soluble beta-1,3-glucan fragments that were taken up by the CR3 of marginated granulocytes. These granulocytes with CR3-bound beta-1,3-glucan-fluorescein were shown to kill iC3b-opsonized tumor cells following their recruitment to a site of complement activation resembling a tumor coated with mAb.

Antigen-Specific Lymphocyte Sequestration in Lymphoid Organs: Lack of Essential Roles for αL and α4 Integrin-Dependent Adhesion or Gαi Protein-Coupled Receptor Signaling

Selective lymphocyte sequestration was described over 30 years ago as the transient withdrawal of Ag-specific lymphocytes from the circulation as a result of their activation in secondary lymphoid organs. We used a TCR-transgenic adoptive transfer system to further characterize the Ag and adjuvant dependence of this process in mice. In addition, we examined the contribution of the alpha(L) and alpha(4) integrin chains as well as Galpha(i) protein-coupled receptor signaling to the retention of Ag-specific T cells in peripheral lymph nodes. Our results demonstrate that selective lymphocyte sequestration is T cell autonomous and adjuvant independent, and that the duration of sequestration is not controlled by the continued presence of Ag in secondary lymphoid organs. This process is not critically dependent on the alpha(L) and alpha(4) integrin chains or Galpha(i) protein-coupled receptor signaling. Selective lymphocyte sequestration may be mediated by redundant mechanisms and/or controlled by novel or nonclassical adhesion or trafficking molecules.

Inhalation of diesel exhaust for three months affects major cytokine expression and induces bronchus-associated lymphoid tissue formation in murine lungs

The authors investigated the effects of exposure to diesel exhaust (DE) on murine lung tissues in vivo. BALB/c and C57BL/6 mice were exposed to DE with low (100 microg/m(3)) and high (3 mg/m(3)) DE particle levels for 3 months. The authors then examined morphological changes and the expression of mRNAs for various cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-4, IL-6, IL-10, IL-12p40, and interferon [IFN]-gamma) and inducible nitric oxide synthase (iNOS) in the lungs, as well as TNF-alpha, IL-1beta, IL-10, IL-12p40, and Mac-1 mRNA expression in alveolar macrophages (AMs). TNF-alpha, IL-12p40, IL-4, and IL-10 mRNA expression were mildly increased, whereas IL-1beta mRNA and iNOS expression were slightly decreased, in the low- and high-level exposure groups. Flow cytometry of bronchoalveolar lavage fluid revealed a significant increase in Mac-1-positive cells in the high-level exposure group. On histological examination, bronchus-associated lymphoid tissue (BALT), containing B and T lymphocytes, had developed only in the high-level exposure group. Chronic inhalation of DE influences cytokine expression in the murine lung, and induces phagocytosis and BALT development. These findings suggest that DE may provoke immunological responses by acting as a foreign body in the lung, and that even low-level exposure may induce allergic reactions.

[Correction of immune and hematopoietic system disorders in experimental toxic hepatitis with Lacto Flor]

Reduction in cells quantity of thymus, lymphatic nodes, bone marrow and rosette formation cells, decrease in erythrocytes and leucocytes number, suppression of antibody production are seen in experimentally developed acute toxic hepatitis (ATH). Lacto Flor preparation was established to have potential properties to restore different immune and hematological systems disorders observed in mice with ATH.

Melatonin blocks dexamethasone-induced immunosuppression in a seasonally breeding rodent Indian palm squirrel, Funambulus pennanti

In vivo effect of dexamethasone and melatonin on immunomodulation has been investigated by studying the lymphocyte proliferation to the mitogen Con A from various lymphoid tissues including bone marrow cells of a seasonally breeding rodent adult male F. pennanti during reproductively inactive phase (October to December). During this phase, animal faces the maximum challenges of the nature (hypothermic stress, scarcity of food and shelter). Dexamethasone treatment (60 microg/day/squirrel) for 60 consecutive days significantly decreased the thymus and spleen activity. The lymphoid tissues mass, total leukocyte, lymphocyte count of peripheral blood, bone marrow and T-cell mediated immune function was also significantly suppressed following the dexamethasone treatment but treatment of melatonin (25 microg/squirrel/day) along with dexamethasone significantly restored the suppressed immune status in squirrels. Further, histological study of the thymus showed profound changes in the cellularity with a depletion of thymocytes in the cortex region of thymic lobules and increased in connective tissues and spindle cells. Melatonin treatment alone increased thymocytes density in thymic cortex, clearly suggesting that melatonin counteracted the experimentally induced immune stress by dexamethasone. Therefore, in nature during reproductively inactive phase of the squirrel a high level of melatonin was noted, that is required to combat nature's stress, which might have increased the internal level of corticoids.

Effects of ethanol on gut-associated lymphoid tissues in a model of bacterial translocation: a possible role of apoptosis

Chronic ethanol intake has been shown to be associated with immune suppression and impairment of epithelial barrier function. We investigated the effects of ethanol on intestinal immunity and its relation to bacterial translocation (BT). Male Wistar rats were assigned to one of three groups and received respective diets for 28 days. The ethanol-fed group [(EG); n=11] received a liquid diet containing 5% [volume/volume (vol./vol.)] ethanol; a pair-fed group [(PFG); n=11] received an isocaloric diet without ethanol; and a third (control) group [(CG); n=11] received water and chow ad libitum. On experimental day 29, animals in the EG and the PFG underwent distal ileum ligature and small intestine inoculation of a tetracycline-resistant Escherichia coli strain (TcR E. coli R6), by means of gastric intubation, followed by duodenal ligature. One hour after inoculation, mesenteric lymph nodes, right lobe of liver, spleen, and left kidney were excised for bacterial studies. Sections of jejunum and colon were immunostained, with the use of antibodies against immunoglobulin (Ig) A, T cells, macrophages, and proliferating cell nuclear antigen (PCNA). Apoptosis was determined by the terminal deoxynucleotidyltransferase TdT-mediated dUDP-biotin nick end labeling (TUNEL) method. Bacterial translocation rates were greater in the PFG compared with findings for the EG. Lamina propria of the jejunum of the EG showed a reduction in the densities of IgA+ cells and T cells compared with findings for the PFG and the CG. Colonic lamina propria of the EG showed reduced densities of IgA+ cells and macrophages compared with findings for the PFG and the CG. Apoptotic index was increased in the EG compared with findings for the PFG and the CG, in both jejunum and colon. Proliferation index was not significantly different among groups. Results of the current study show that chronic ethanol ingestion led to a reduction of cellular and humoral components of the intestinal mucosa, possibly by cell loss as a result of ethanol-induced apoptosis. The reduced rates of BT observed after chronic ethanol intake seem to indicate that factors irrespective of immune function might be involved in BT inhibition.

Immunotoxic effects of Ochratoxin A in wistar rats after oral administration

Ochratoxin A (OTA) is a mycotoxin produced by species of the genus Aspergillus and Penicillium. Human exposure has been demonstrated worldwide and its origin seems to be the intake of contaminated foods. The kidneys are the target organ of this mycotoxin. Immunotoxic and genotoxic effects of OTA were investigated in Wistar male rats (aged 12 weeks), treated by gavage with 50, 150 or 450 microg OTA/kg body weight for 28 days, in the context of a general toxicity study, which was designed following the recommendations of OECD guideline 407. At the end of the study, the mean plasma concentration of the mycotoxin was determined, several immune function assays were performed and bone marrow smears were obtained and stained in order to analyse micronuclei in polychromatic erytrocytes. Mean plasma concentration was found to be 187, 600 and 807 microg/L, respectively. At the highest dose, a decrease in body weight gain was observed. Histopathological investigations revealed tubulonephrosis and acute tubular necrosis in the kidneys of the animals treated with OTA. The frequency and severity of the lesions increased with the dose. The response of splenocytes to sheep red blood cells was decreased in a dose-dependent manner; however, nonstatistically significant differences were obtained. The natural killer cell activity was strongly affected by OTA treatment. Cytotoxic T lymphocyte activity was lower in the animals exposed to 50 microg OTA/kg b.w. but was not modified in the groups exposed to 150 and 450 microg OTA/ kg b.w. The bacteriolytic capability of macrophages was significantly reduced in groups exposed to 50 and 450 microg OTA/ kg b.w. The number of micronuclei in bone marrow polychromatic erytrocytes did not vary significantly with respect to the control at any dose, but a false negative result can not be ruled out because the exposure doses were much lower than those recommended in OECD guideline 474.

Ultrastructural study of pleural lymphatic drainage unit and effect of nitric oxide on the drainage capacity of pleural lymphatic stomata in the rat

The objective of this study was twofold: first to investigate the ultrastructure of the lymphatic drainage unit on the costal pleura of rats by electron microscopy, and secondly to examine the effect of nitric oxide on the pleural lymphatic stomata and fluid absorption from the pleural cavity. The lymphatic drainage unit of the rat costal pleura is composed of three special components: the lymphatic stomata between the mesothelial cells, the initial part of the lymphatic vessels and the underlying connective tissue containing many foramina. The unit is the main passage to drainage fluid, particles and cells in the pleural space. To investigate the regulator of the lymph drainage, nitric oxide synthase inhibitor and nitric oxide donor were injected into the peritoneal cavity of the rats, respectively. Trypan blue was used as tracer. The ultrastructural changes of pleural lymphatic stomata were observed under scanning electron microscope and analyzed by a computer image processing system. It turned out that the area and density of the pleural lymphatic stomata were positively correlated with the nitric oxide quantity (p < 0.05). After the tracer was injected into the pleural cavity, the nitric oxide donor group exhibited a higher trypan blue concentration than the control group (p < 0.05). The ability of the pleura to absorb trypan blue was enhanced because of the larger opening of the lymphatic stomata (p < 0.05). It is suggested that nitric oxide can increase lymphatic absorption of the pleura by opening pleural lymphatic stomata.

[Effect of Lacto Flor on immunological and hematopoietic systems in experimental hemolytic anemia]

Negative changes in organs of immune and blood systems have been observed under experimentally produced hemolytic anemia. Total recovery of cellularity in central and peripheric immunity organs and blood profile was found with Lactoflor use.

Lymphocyte egress from thymus and peripheral lymphoid organs is dependent on S1P receptor 1

Adaptive immunity depends on T-cell exit from the thymus and T and B cells travelling between secondary lymphoid organs to survey for antigens. After activation in lymphoid organs, T cells must again return to circulation to reach sites of infection; however, the mechanisms regulating lymphoid organ exit are unknown. An immunosuppressant drug, FTY720, inhibits lymphocyte emigration from lymphoid organs, and phosphorylated FTY720 binds and activates four of the five known sphingosine-1-phosphate (S1P) receptors. However, the role of S1P receptors in normal immune cell trafficking is unclear. Here we show that in mice whose haematopoietic cells lack a single S1P receptor (S1P1; also known as Edg1) there are no T cells in the periphery because mature T cells are unable to exit the thymus. Although B cells are present in peripheral lymphoid organs, they are severely deficient in blood and lymph. Adoptive cell transfer experiments establish an intrinsic requirement for S1P1 in T and B cells for lymphoid organ egress. Furthermore, S1P1-dependent chemotactic responsiveness is strongly upregulated in T-cell development before exit from the thymus, whereas S1P1 is downregulated during peripheral lymphocyte activation, and this is associated with retention in lymphoid organs. We find that FTY720 treatment downregulates S1P1, creating a temporary pharmacological S1P1-null state in lymphocytes, providing an explanation for the mechanism of FTY720-induced lymphocyte sequestration. These findings establish that S1P1 is essential for lymphocyte recirculation and that it regulates egress from both thymus and peripheral lymphoid organs.

Functional genomic analysis of the response of HIV-1-infected lymphatic tissue to antiretroviral therapy

Highly active antiretroviral therapy (HAART) curtails human immunodeficiency virus type 1 (HIV-1) replication in lymphatic tissues and partially reverses the pathological damage associated with infection, but the genes that mediate these pathological and reparative processes remain largely unknown. To identify these genes, we used microarrays to profile gene expression in serial lymph node biopsy specimens obtained before and after treatment. We discovered approximately 200 treatment-responsive genes, many of them known mediators and moderators of immune activation and defenses, particularly innate defense genes, which, surprisingly, were expressed at all stages of HIV-1 infection. Most of the rest of the treatment-responsive genes we categorized as mediators of trafficking, reformation of active follicles, and tissue repair. We propose a model in which nearly counterbalanced functions of mediators and moderators of immune activation and defenses account for the slow dynamics of HIV-1 infection before treatment. This model suggests that there could be a role for anti-inflammatory agents, alone or in combination with HAART, in treating HIV-1 infection by tipping this balance to mitigate pathology.

Chemically induced immunotoxicity in a medium-term multiorgan bioassay for carcinogenesis with Wistar rats

A variety of chemicals can adversely affect the immune system and influence tumor development. The modifying potential of chemical carcinogens on the lymphoid organs and cytokine production of rats submitted to a medium-term initiation-promotion bioassay for carcinogenesis was investigated. Male Wistar rats were sequentially initiated with N-nitrosodiethylamine (DEN), N-methyl-N-nitrosourea (MNU), N-butyl-N-(4hydroxybutyl)nitrosamine (BBN), dihydroxy-di-n-propylnitrosamine (DHPN), and 1,2-dimethylhydrazine (DMH) during 4 weeks. Two initiated groups received phenobarbital (PB) or 2-acetylaminofluorene (2-AAF) for 25 weeks and two noninitiated groups received only PB or 2-AAF. A nontreated group was used as control. Lymphohematopoietic organs, liver, kidneys, lung, intestines, and Zymbal's gland were removed for histological analysis. Interleukin (IL)-2, IL-12, interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), IL-10, and transforming growth factor beta1 (TGF-beta1) levels were determined by ELISA in spleen cell culture supernatants. At the fourth week, exposure to the initiating carcinogens resulted in cell depletion of the thymus, spleen and bone marrow, and impairment of IL-2, IL-12, and IFN-gamma production. However, at the 30th week, no important alterations were observed both in lymphoid organs and cytokine production in the different groups. The results indicate that the initiating carcinogens used in the present protocol exert toxic effects on the lymphoid organs and affect the production of cytokines at the initiation step of carcinogenesis. This early and reversible depression of the immune surveillance may contribute to the survival of initiated cells facilitating the development of future neoplasia.

Haemato-biochemical and immuno-pathophysiological effects of chronic toxicity with synthetic pyrethroid, organophosphate and chlorinated pesticides in broiler chicks

Haemato- biochemical and immuno-pathophysiological changes following feeding of broiler chicks with 20 ppm fenvalerate (synthetic pyrethroid, SP), 2 ppm monocrotophos (organophosphate, OP) and 2 ppm endosulfan (chlorinated hydrocarbon, CH) were studied. Four groups of broiler birds (30 each) were fed poultry mash without (control) or mixed with pesticides for 8 weeks. Blood glucose, serum globulin and acetyl cholinesterase (AChE) activity level were decreased (P<0.01) in all treated groups compared to control, but not the serum albumin and BUN. The total ATPase activity was enhanced (P<0.01) in fenvalerate and monocrotophos than birds in control group. Body weight, total erythrocyte count, packed cell volume, haemoglobin, eosinophil and monocyte count did not show any changes. Total leucocytes and T-lymphocyte count was lower (P<0.01) in all treated groups as compared to control group. B-cell count (P<0.01), mean 2-4-dinitrofluorobenzene (DNFB) dermal sensitivity score and splenic indices from graft vs. host reaction (P<0.05) were decreased in fenvalarate and endosulfan but the values for monocrotophos were intermediate between control and other treated groups. Pesticide intoxication reduced nitroblue tetrazolium (NBT) positive cells (active splenic macrophages) (P<0.05) and spleen weight (P<0.01). Whereas bursal weight was reduced only with endosulfan, thymic weight was reduced on endosulfan and fenvalerate-treated feed. Microscopic examination of these organs further revealed atrophy/hypoplasia, decrease in the size of follicles with depletion of lymphocytes and haemorrhages in thymus. The study concludes that the chronic exposure of chicks to small amount of SP, OP and CH pesticide leads to deleterious effects on metabolism and immune system of birds.

[Effect of epitalon on the immunity and hemostasis in hypophysectomized chicken and old hens]

Neonatal hypophysectomy in chicken, as well as that in old hen has been established to entail in 1,5 months after surgery cellular and humoral immunity disturbances, pronounced hypercoagulation and fibrinolysis depression. Administration of Epitalon (Ala-Glu-Asp-Gly) to a large extent eliminates revealed shifts. This effect appeared to be stronger in neonatally hypophysectomized chicken than in old hens.

Stimulation of bronchus-associated lymphoid tissue in rats by repeated inhalation of aerosolized lipopeptide MALP-2

OBJECTIVE

Bronchus-associated lymphoid tissue (BALT) is a part of the integrated mucosal immune system. It may play an important functional role for antigen uptake and induction of specific immune reactions. The aim of this study was to investigate whether it is possible to induce or modulate BALT by the repetitive inhalation of the synthetic lipopeptide MALP-2.

METHODS

Female Lewis rats (245 +/- 19 g) inhaled 25 microg of MALP-2 six times at intervals of 1 week. One week after the last inhalation, they were sacrificed. Cells of the bronchoalveolar lavage and the left lung were investigated by flow cytometry. The middle lobe of the right lung was embedded in paraffin. BALT was semiquantitatively measured in 15 serial cross sections per animal.

RESULTS

After repetitive inhalation of the diluent as well as MALP-2, BALT was found. The total area was increased after repetitive treatment with MALP-2. In addition, the preferential incidence of BALT was higher after MALP-2 application, in association with a bronchial diameter of 0.6-1 mm. The cellular analysis revealed no differences in the number of leukocyte subsets between the control and MALP-2 group.

CONCLUSION

MALP-2 is a potent local stimulator and can be used to modulate BALT by repetitive inhalant treatment. The functional significance of enlarged or activated BALT has to be elucidated in future studies.

[The influence of the dietary polyunsaturated fatty acids on the phagocyte's functional activity in rats]

The influence of dietary polyunsaturated fatty acids on the superoxid anion production by peritoneal macrophages and phagocytosis by blood neutrophiles in male Wistar rats weighting 127.0 +/- 3.2 r was investigated after 3 months feeding. Rats fed isocaloric purified diets contained 24% fat representing combinations of lard, sunflower oil and fish oil (eiconol) providing the ratios of w6/w3 fatty acids equal 49.0; 6.1; 1.1. The increasing of superoxide formed by peritoneal macrophages and phagocytic activity of neutrophiles in the group received diet with the minimal ratios of w6/w3 fatty acids compared to that in rats fed diet with ratio 49.0 was noted. The increased activity of mononuclear-phagocytic system was confirmed by morphological investigation of peripheral lymphoid organs.

Transient early post-inoculation anti-retroviral treatment facilitates controlled infection with sparing of CD4+ T cells in gut-associated lymphoid tissues in SIVmac239-infected rhesus macaques, but not resistance to rechallenge

Like human immunodeficiency virus infection of humans, infection of rhesus macaques with pathogenic simian immunodeficiency virus (SIV) strains typically results in persistent progressive infection, leading to clinically significant immunosuppression. In previous studies, we administered short term anti-retroviral treatment, shortly after intravenous inoculation with SIVsmE660, in an effort to allow immunologic sensitization under conditions not characterized by overwhelming cytopathic infection compromising the developing immune response. We showed that such treatment allowed control of off treatment viremia and was associated with resistance to rechallenge. Control of off treatment viremia was associated, at least in part, with CD8+ lymphocytes, based on in vivo CD8 depletion studies. In the present study, six rhesus macaques were infected intravenously with 100 MID50 of SIVmac239; four then received 30 days of treatment with tenofovir 9-[2-(R)-(phosphonomethoxy)propyl]adenine (PMPA); 20-30 mg/kg, subcutaneously) starting 24 hours post-inoculation. Tenofovir-treated animals showed low (<500 copy Eq/ml) or undetectable (<100 copy Eq/ml) plasma SIV RNA levels during treatment, with undetectable plasma viremia following discontinuation of treatment. Plasma SIV RNA remained <100 copy Eq/ml, even after depletion of CD8+ lymphocytes, 6 weeks after discontinuation of tenofovir treatment. In contrast to untreated infected control animals that showed substantial depletion of CD4+ T cells from gut-associated lymphoid tissues (GALT), tenofovir-treated animals showed sparing of GALT CD4+ T cells both during the treatment period and in the off treatment follow-up period. However, in contrast to earlier results with animals infected with SIVsmE660, in the present study, the animals did not develop readily measurable cellular anti-SIV immune responses, and did not resist homologous rechallenge with SIVmac239, administered 44 weeks after the initial infection. Differences in the animals and virus strains employed may in part account for the differences in results observed. Comparative analysis of virologic and immunologic parameters in this model system may provide important insights for understanding the basis of effective immunologic control of SIV infection.

Anti-CD20 treatment depletes B-cells in blood and lymphatic tissue of cynomolgus monkeys

INTRODUCTION

Macaque species offer a valuable model for translational allo-transplantation and tolerance studies. Cardiac allograft vasculopathy in Macaca fascicularis is associated with elaboration of anti-donor antibodies. Since T-independent pathways of B cell activation have been described, and anti-B cell strategies have proven to be a fruitful tolerogenic adjunct in rodent and xenogenic models, here we investigate whether an anti-CD20 antibody (rituximab) would be useful to deplete B-cells in a pre-clinical allo-transplantation setting in macaques.

METHODS

Three cynomolgus macaques which had previously rejected a cardiac allograft and one with concurrent subacute vascular rejection were treated weekly with rituximab 20 mg/kg i.v. for 4 and 2 weeks, respectively. B-cell levels (CD19+ cells) were measured by flow cytometry in peripheral blood, spleen, lymph node and bone marrow cells at various intervals after initiation of treatment. B-cells and plasma cells were also analyzed by immunohistochemistry at necropsy in spleen, lymph node, tonsil and thymus tissue sections. Anti-donor antibody titers were measured by flow cytometry.

RESULTS

B-cells expressing CD19 were not detectable in the peripheral blood in any animal within 24 h after initial treatment, or over the ensuing month. At necropsy, the germinal centers in spleen and lymph node were completely depleted of CD20+ B-cells in 2 animals, leaving a hypocellular trabecular pattern around preserved plasma cell follicles. Substantial but incomplete depletion of B-cells was demonstrated in the other 2 animals, in each instance immunohistochemical findings in spleen and lymph node exhibiting higher sensitivity for residual B-cells compared to FACS. Anti-donor antibody titers exhibited kinetics similar to untreated animals over this short follow-up.

COMMENT

Treatment with anti-CD20 very efficiently depletes peripheral and tissue B-cells but not plasma cells in this macaque species. Biopsy of lymph node is necessary and may be sufficient to assess B-cell clearance in secondary lymphoid organs in this model.

Repeated dose oral toxicological evaluation of concentrated barley beta-glucan in CD-1 mice including a recovery phase

The cholesterol-lowering effect observed following consumption of oats and barley is attributable to the beta-glucan component of the soluble fiber fraction of these cereal grains. beta-Glucan has also been reported to modulate immune activity, however, few studies have evaluated the hematological effects of beta-glucan following oral exposure. In the current study, a concentrated beta-glucan (64%) preparation from barley (Barley Betafiber) was blended into mouse feed at concentrations of 1, 5, or 10% (corresponding to approximately 0.7, 3.5, and 7% beta-glucan) and evaluated in CD-1 mice. Plasma was collected for clinical chemistry and hematological measurements at the initiation of the study and again following 14 and 28 days of exposure. Plasma was also collected from animals that consumed the same diets for 28-days but were switched to control diet (containing no supplemental beta-glucan) for an additional 14-day period to evaluate reversibility or delayed occurrence of treatment-related changes. Half of the animals were sacrificed for histopathologic analysis following the 28-day exposure period and the other half were evaluated following the recovery period. Histopathologic analysis focused on primary lymphoid organs and lymph nodes proximal and distal to the route of exposure. An additional group of untreated animals (nai;ve) was bled and sacrificed at day 0, 14, 27 and 41 for comparison of the hematology parameters with those of the control group because it was not known if multiple blood draws would affect hematology parameters. Compared to animals consuming the control diet, no treatment-related adverse effects were observed in hematological or clinical chemistry measurements or in organ weights and immunopathology in either sex following consumption of concentrated barley beta-glucan for 28-days or following the recovery period. Likewise, no differences were observed between the nai;ve and control groups. Results from this study showed that consumption of concentrated barley beta-glucan did not cause treatment-related inflammatory or other adverse effects in CD-1 mice.

Plasticity of IL-2 and IL-2 receptor chains in rat lymphoid tissues in situ after stimulation with staphylococcal enterotoxin A

Although the effects of mitogens on the synthesis of interleukin-2 (IL-2) and IL-2 receptor (IL-2r) have been described, a detailed in situ analysis of the spatio-temporal changes of the expression of the IL-2 gene and the three IL-2r components in lymphoid tissues is still missing. Therefore, we analyzed the IL-2 and IL-2r expression after a staphylococcal enterotoxin A (SEA)-induced T cell activation on a cellular and anatomical basis in the Wistar rat. SEA caused a rapid induction of IL-2 mRNA in T cells of spleen, lymph node, and thymus, followed by the appearance of high systemic IL-2 serum levels (5 ng/ml), and a significant increase of CD25 on CD4+ and CD8+ lymphocytes. The histotopographic analysis of the IL-2r chains revealed a strong upregulation of IL-2r alpha (alpha) and IL-2r beta (beta) mRNAs in similar T cell specific compartments of spleen, lymph node, and thymus as seen for IL-2 mRNA. The abundant constitutive expression of IL-2r gamma (gamma) mRNA was unaffected by SEA. The parallel upregulation of IL-2, IL-2ralpha, and beta chains in conjunction with the continuous presence of the IL-2rgamma chain predominantly in T cell regions of immune organs suggests that the biological effects of IL-2 are essentially limited to T cells, at least after superantigen stimulation.

The cGMP synthesis and PKG1 expression in murine lymphoid organs

Numerous reports indicate that cyclic 3',5' guanosine monophosphate (cGMP) is involved in the regulation of immune processes. However, the mechanisms responsible for the synthesis of this nucleotide and its signaling pathways in immune cells are still not well recognized. The aim of our studies was to establish: 1) which form of guanylyl cyclase (GC) synthesizes cGMP in murine lymphoid organs and 2) whether the same organs express the isoforms PKG1alpha and/or PKG1beta of protein kinase G, known as possible target for synthesized cGMP. Cells isolated from thymus, lymph nodes, and spleen were treated with activators (SNP, ANP, CNP, STa) of soluble or particulate cyclases. Sodium nitroprusside (SNP) elevated intracellular cGMP 2-fold in thymic and lymph node cells and about 10-fold in spleen cells. Atrial natriuretic peptide (ANP) caused modest but statistically significant increases of cGMP in cells of all three organs. Additionally, spleen cells elevated their cGMP content about 2-fold in response to C-type natriuretic protein (CNP). In cellular homogenates of the all analyzed organs, the antibody anti-PKG1beta stained the 78 kDa band corresponding to the molecular mass of PKG1. Only homogenates of spleen cells were stained by the antibody recognizing PKG1alpha. Our results indicate that in the investigated organs cGMP may be synthesized mainly by soluble GC in response to nitric oxide. The modest increase of cGMP upon stimulation by ANP suggests that in all these organs either exists only a small subpopulation of cells that express particulate cyclase GC-A or GC-A is expressed at very low level. In spleen cells, however, cyclase GC-B appears to be the more active enzyme. Elevated cGMP concentration may in turn activate PKG1beta in thymus, lymph node, and spleen cells and also PKG1alpha in spleen cells.

Minimal effects on immune parameters following chronic anti-TGF-beta monoclonal antibody administration to normal mice

Mice genetically deficient in TGF-beta1 or TGF-beta signaling capacity in T or B cells demonstrate profound immune dysregulation, as evidenced by increased lymph node size, expression of markers of memory/activation on T cells, inflammation in a variety of tissues and development of autoantibodies. However, this constant and complete lack of TGF-beta1 or TGF-betaR signaling may not reflect effects of TGF-beta neutralization using antibodies in mature animals. Thus, the present studies were designed to determine if administration of an anti-TGF-beta monoclonal antibody (neutralizes TGF-beta1, 2 and 3) to mature, normal mice results in evidence of immune dysregulation or immune-mediated pathology. An initial study examined daily administration of 0.25, 0.75 and 2.5 mg/kg of anti-TGF-beta to mice for three weeks, achieving blood levels of as high as 9 mg/ml. Comprehensive hematological and histopathological evaluation showed no evidence of pathology. A second study was designed to extend the antibody treatment period and further examine the functional status of the immune system. Mice were injected with 1 mg/mouse (approximately 50 mg/kg) of anti-TGF-beta (1D11) three times per week achieving circulating blood levels of 1-2 mg/ml. Many parameters of immune status were assessed, including natural killer (NK) cell activity, lymphocyte proliferative responses, phagocytic activity, phenotypic assessment of leukocyte subsets, and serum measurements of proinflammatory cytokines, autoantibodies and immunoglobulin isotypes. In addition, histopathological assessment of heart, lungs, liver, kidney, salivary glands, skin, spleen and lymph nodes was also performed. Very few of the multiple immune parameters examined showed detectable changes in anti-TGF-beta-treated mice. Changes that were observed were primarily restricted to the spleen and included increased spleen cell recoveries, increased percentages of macrophages, decreased percentages of NK cells, decreased phagocytic activity, decreased proliferative responses to mitogens and slight increases in T and B cells displaying an activated phenotype. Many of these same parameters examined in the lymph nodes were not altered by the anti-TGF-beta treatment. The thymus was decreased in size, but altered only slightly in one population of developing T cells. Most of the changes observed were modest and returned to control levels after discontinuation of treatments. The only serological finding was an increase in IgA levels in anti-TGF-beta-treated mice, but not in any other isotype. Finally, there was no evidence of increased inflammation in any of the peripheral tissues examined in the anti-TGF-beta-treated mice. In conclusion, although there were changes in some of the immunological parameters examined in these studies, they were few and typically reversed following discontinuation of treatment. The modest nature of the changes observed in these studies is particularly evident when compared to published data of those same parameters examined in mice genetically deficient in TGF-beta1 or mice having TGF-beta unresponsive T or B cells. Thus, there does not appear to be any significant immune dysregulation detectable after long-term antibody-mediated neutralization of TGF-beta in normal mice.

Interleukin-7-dependent production of RANTES that correlates with human immunodeficiency virus disease progression

There is a relationship between CD4-T-cell number and circulating interleukin 7 (IL-7) levels in human immunodeficiency virus (HIV)-positive individuals. Here, we show that IL-7 induced a dose-dependent production of CCL3 (MIP-1alpha), CCL4 (MIP-1beta), and CCL5 (RANTES) in peripheral blood mononuclear cells (PBMC), ex vivo tonsil lymphoid tissue of HIV(-) individuals, and PBMC from HIV(+) individuals, suggesting that IL-7 may regulate beta-chemokine production in vivo. In a cross-sectional study of HIV(+) individuals (n = 130), a weak but significant correlation between IL-7 and RANTES was noted (r = 0.379; P < 0.001). Remarkably, the correlation between IL-7 and RANTES increased to an r value of 0.798 (P < 0.001) if individuals with low CD4 cell counts (<200 cells/ micro l) were excluded from the analysis. Our results suggest that there is a relationship between IL-7 and the production of RANTES both in vitro and in vivo that is lost in immune-compromised patients (CD4 count of <200 cells/ micro l) but that could be restored by antiretroviral therapy. Unlike the case for IL-7, high levels of RANTES suggest an intermediate stage of HIV disease progression.

Neurotoxicity and immunotoxicity assessment in CBA/J mice with chronic Toxoplasma gondii infection and single-dose exposure to methylmercury

Toxoplasma gondii is a protozoan parasite that localizes in the brain where it can cause life-threatening disease. Methylmercury (MeHg) is a well-documented neurotoxicant that accumulates in the brain. We investigated end points associated with immunotoxicity and neurotoxicity in mice exposed to MeHg during a chronic T. gondii infection. Two groups of 6-week-old, female CBA/J mice were either fed 25 T. gondii tissue cysts of the ME-49 strain or given vehicle. Six weeks later, half of the mice in each group were orally gavaged with a single dose of 20 mg/kg body weight of MeHg, creating four groups of mice (vehicle control, T. gondii, MeHg, and T. gondii/MeHg). Mice were sacrificed 7 days post MeHg exposure. MeHg exposure caused a significant decrease in mouse body weight. MeHg administration resulted in an increase of splenic cellularity and spleen-to-body weight ratios. MeHg had no significant effect on the percentages of CD4(+), CD8(+), or non-T-cell subpopulations in the spleen. MeHg dosed mice demonstrated an increase in absolute numbers of splenic CD4(+), CD8(+), or non-T cells when compared to mice in control and T. gondii-infected groups. Thymic CD4(+)CD8(+) T-cell subpopulations were decreased (p <.05) by MeHg with or without a concurrent T. gondii infection. There was a significant (p <.05) increase in brain tissue cyst counts within the group exposed to both MeHg and T. gondii (16 +/- 4, mean +/- SE, n = 7) versus T. gondii alone (4 +/- 1, n = 8). Histopathological examination demonstrated encephalitis, gliosis, and meningitis in brains from mice infected with T. gondii. These data indicate that exposure to both MeHg and T. gondii has synergistic effects, with effects of MeHg especially on the immune system.

[Comparative analysis of disorders in duodenal lymphoid tissue of mice treated with azathioprine and herbicide 2,4-dichlorophenoxyacetic acid and their correction by plant and animal origin remedies]

Comparative study of disturbances of intramural duodenal lymphoid tissue in mice, which were induced by the action of "classical" immunosuppressing drug azathioprine and by herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) showed similar immunosuppressing effect that was more potent after herbicide treatment. Significant reduction in the number of the cells of lymphoid series found in the duodenal wall was accompanied by inflammatory-destructive processes and adipose tissue outgrowth. Administration of hypolipidemic plant extract to animals immunosuppressed with either azathioprine or herbicide 2,4-D, promoted the restoration of intramural duodenal morphological structures and the restitution of lymphoid cell parameters in lamina propria practically to the level of control values. The results obtained indicate the immuno-correcting effect of the plant extract, which is determined by a rich complex of biologically active substances of its components. Active thymic fraction (AFT-2) was also found to possess an immuno-correcting effect, promoting the restoration of cellular composition of diffuse lymphoid tissue in duodenal lamina propria. Immuno-correcting effect of AFT-2 seems to result from the activity of its component thymic peptides.

Biodefense function of omental milky spots through cell adhesion molecules and leukocyte proliferation

To evaluate the immunological functions of the greater omentum in the peritoneal cavity, the localization of cell adhesion molecules (CAMs) on mesothelial cells and leukocytes in the omental milky spots were studied in normal and lipopolysaccharide (LPS)-stimulated mice by means of immunoelectron microscopy. The milky spots featured numerous leukocytes among the dome-shaped mesothelial cells, even in the normal stable state. Leukocyte integrins LFA-1, Mac-1, and VLA-4 were preferentially localized to microvilli and ruffles of macrophages and lymphocytes. The mesothelial cells of the milky spots showed higher ICAM-1 levels than did those of other omental regions, and fibronectin was detected in the stomata. The number of leukocytes markedly increased following an increase in proliferating cell nuclear antigen (PCNA)-positive cells in the milky spots after LPS stimulation. The mesothelial cells contained VCAM-1 newly restricted to the microvilli and increasing amounts of ICAM-1. These results show that the omental milky spots are active sites for leukocyte migration and peritoneal leukocyte supply because of the presence of adhesion molecules and active cell proliferation. Proliferative active leukocytes and those that have migrated from vessels pass through the stomata via an interaction of VLA-4 and fibronectin, adhere to the microvilli of the activated mesothelial cell surface as the result of an interaction between ICAM-1/VCAM-1 and integrins, and exude into the peritoneal cavity. Much of the exudation and adhesion of leukocytes seen in the milky spots of LPS-stimulated mice may be attributable to an increase in cell proliferation and in the amounts of ICAM-1 and VCAM-1.

Persistent abnormalities in lymphoid tissues of human immunodeficiency virus-infected patients successfully treated with highly active antiretroviral therapy

Effective highly active antiretroviral therapy (HAART) for human immunodeficiency virus type 1 is associated with virus suppression and immune reconstitution. However, in some patients, this reconstitution is partial or incomplete because CD4(+) cell counts do not increase significantly. This may be due to damage in the microenvironment of lymphoid tissues (LTs), where CD4(+) T cells reside. To test this hypothesis, LT samples were obtained from 23 patients enrolled in a prospective trial that compared 3 different HAART regimens. Analysis of LT architecture and CD4(+) T cells populations revealed abnormalities in 100% of the LT samples, especially in the follicles, with 43% showing absence, 14% showing regression, and 43% showing hyperplasia. CD4(+) T cell populations were abnormal in 16 (89%) of 18 tissue samples, with 7 (39%) of 18 decreased by >50% of normal levels. These data are consistent with the hypothesis that persistent abnormalities in the microenvironment can influence immune reconstitution and document persistent LT abnormalities with HAART not detected by measures of peripheral CD4(+) T cell count.

Immunosuppressive effects of Marek's disease virus (MDV) and herpesvirus of turkeys (HVT) in broiler chickens and the protective effect of HVT vaccination against MDV challenge

Much of the impact of Marek's disease in broiler chickens is considered to be due to immunosuppression induced by Marek's disease virus (MDV). The present study evaluates the effects of an Australian isolate of pathogenic MDV (strain MPF 57) and a non-pathogenic vaccinal strain of herpesvirus of turkeys (HVT) (strain FC 126) on the immune system of commercial broiler chickens for 35 days following challenge at days 0 or 3 of age. It also investigates the extent of protection provided by HVT vaccine against MDV-induced immunosuppression. Immune system variables, including relative lymphoid organ weight, blood lymphocyte phenotype (CD45+/CD3+, putatively T, and CD45+/LC+, putatively B) and antibody production following vaccination against infectious bronchitis (IB) at hatch, were used to assess the immune status of chickens. Immunosuppression was also assessed by susceptibility to secondary challenge with pathogenic Escherichia coli on day 29 post-MDV challenge. MDV infection reduced the weight of the thymus and bursa of Fabricius, the numbers of circulating T lymphocytes and B lymphocytes, and IB antibody titre. The timing of these effects varied. MDV infection greatly increased susceptibility to E. coli infection. HVT alone caused mild depletion of T and B lymphocytes but no effect on immune organ weight or IB titre. Vaccination with HVT provided good protection against most of the immunosuppressive effects of MDV but not against MDV-induced growth impairment and reduced responsiveness to IB vaccination, suggesting that recent Australian strains of MDV may be evolving in virulence to overcome the protective effects of HVT.

Treatment of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type with cladribine: a phase II study

PURPOSE

As chemotherapy has not been extensively studied in patients with lymphoma of the mucosa-associated lymphoid tissue (MALT), we initiated a prospective study to evaluate the activity of the nucleoside analog cladribine (2-chlorodeoxyadenosine [2-CdA]) in this disease.

PATIENTS AND METHODS

Patients with histologically verified MALT-type lymphoma were enrolled. 2-CdA was administered at a dose of 0.12 mg/kg body weight on 5 consecutive days, as a 2-hour infusion. Cycles were repeated every 4 weeks for a maximum of six cycles.

RESULTS

Nineteen patients with gastric and seven patients with extragastric MALT lymphoma were enrolled. All patients were chemotherapy-naive, and two had been locally irradiated before systemic relapse of the lymphoma. A total of 102 cycles was administered to our patients (median number of cycles per patient, four). All 25 assessable patients responded to treatment: 21 patients (84%) achieved complete remission (CR) and four patients achieved partial remission. All patients (100%) with gastric presentation, but only three patients (43%) with extragastric presentation, achieved CR. Toxicities were moderate and mainly hematologic and required dose reduction and/or premature discontinuation of therapy in only three cases. Two patients died from vascular events, one shortly after the first cycle because of myocardial infarction and the other from stroke 3 months after the second course. Three patients relapsed after 13, 18, and 22 months and one patient showed progressive disease after 15 months. At present, 24 patients are alive at a median follow-up time of 32 months.

CONCLUSION

Our data demonstrate that 2-CdA is highly effective in inducing CR in 84% of patients with MALT-type lymphoma.

Immunomodulation by diethylstilbestrol is dose and gender related: effects on thymocyte apoptosis and mitogen-induced proliferation

It is believed, but not proven, that the immunomodulatory effects of DES may vary with the dose and/or gender. To address these critical gaps in the literature, diethylstilbestrol (DES) was administered to female and male CD-1 mice as four subcutaneous injections for 1 week at 0, 5, 15, and 30 microg/kg bw doses, and immunological and reproductive effects examined a day after the last injection. Female thymuses were significantly larger than their male counterparts. Short-term administration of DES to female or male mice neither induced thymic atrophy nor altered the relative percentages of thymic subsets. Nevertheless, DES treatment of female or male mice induced a dose-related apoptosis of CD4(+)8(+), CD4(+)8(-) and CD4(-)8(+) subsets as analyzed by 7-amino-actinomycin D (7-AAD). Immature CD4(-)8(-) subset of thymocytes from females was also affected by high dose DES. The pattern of mitogen-induced proliferation of splenic lymphocytes varied with the dose of hormone and the gender. In females, splenic lymphocytes from low dose DES (5 microg/kg bw)-treated mice exhibited an increased proliferative response to Con-A, LPS or PMA/ionomycin compared with controls. Similar cultures from mice treated with higher doses of DES (15 or 30 microg/kg bw) did not manifest an increased proliferative response, but rather showed a trend for suppressed proliferation, especially in response to Con-A. In males, DES had minimal effects with the exception of increased proliferative response to Con-A in splenocytes from medium-dose-DES-treated mice. The changes in mitogen-induced proliferation in DES-treated female mice were not mirrored by similar changes in the relative numbers of CD90(+) or CD45R(+) cells, or in ratios of anti-apoptotic Bcl-2 to apoptotic Bax proteins. Con-A-activated splenocytes from DES-treated mice, particularly from females, had a decreased ability to secrete interferon-gamma compared with controls. Taken together, these findings suggest that short-term exposure to DES has differential immunological effects depending upon the dose of hormone and sex.

Dexamethasone-induced apoptosis in immune cells from peripheral circulation and lymphomyeloid tissues of juvenile clearnose skates, Raja eglanteria

Juvenile clearnose skates (Raja eglanteria) were injected intramuscularly with dexamethasone-21-phosphate at 50, 75, and 100mg/kg body weight. After 24h, skates were sacrificed and lymphomyeloid tissues (thymus, spleen, Leydig organ, and epigonal organ) were removed and whole blood was sampled. Tissues were used fresh for imprints or prepared for histology by solvent fixation or freezing in liquid nitrogen. Apoptosis in fixed tissues was assessed by transmission electron microscopy. Frozen sections and cytospin preparations of peripheral blood leukocytes (PBL) were evaluated by the TUNEL reaction to detect DNA strand breaks. Dexamethasone treatment increased apoptotic activity in all lymphomyeloid tissues as well as in PBL. These studies demonstrate that immune cells of elasmobranchs have the capacity for glucocorticoid-driven apoptosis, and that programmed cell death as a mechanism to regulate immune cell production appears to have been conserved during vertebrate evolution.

Effects of dietary wheat germ deprivation on the immune system in Wistar rats: a pilot study

Bioactive molecules that can gain access to body tissues through the gastrointestinal tract may interact with immune regulatory circuits and effector functions. Among these are plant lectins, such as wheat germ (WG) agglutinin, which constitute common components of the human diet and target the immune system on a daily basis. Dietary bioactive molecules might be considered as immunomodulatory signals. To investigate the possible effects on the immune system of the long-term absence of such signals, two groups of rats were fed on a diet containing or deprived of WG. The WG-deprived diet induced a state of functional unresponsiveness in lymphocytes from primary and secondary lymphoid organs, as evaluated by in vitro stimulation with T cell mitogen phytohemoagglutinin (PHA) and B cell mitogen lypopolysaccarides (LPS). The unresponsive state of the immune cells could be reversed by injection of antigen emulsified in oil with inactivated mycobacteria (complete Freund's adjuvant, CFA) Dietary signals can thus interact with the immune system possibly influencing its shaping during ontogenesis.

Transport of chitosan microparticles for mucosal vaccine delivery in a human intestinal M-cell model

Uptake of particulate antigen carrier systems by specialized M-cells of the gut-associated lymphoid tissue is still a limiting step in inducing efficient immune responses after oral vaccination. Although transport of soluble drugs over the epithelial barrier of the gut is extensively studied in vitro by using the Caco-2 cell model, this was for long time not possible for particles due to the absence of M-cells. By co-culturing Caco-2 cells with cultured human B-lymphocytes (Raji-cells), cells which are morphologically and functionally similar to M-cells can be induced. This human M-cells model makes it possible to study the uptake of microparticles for oral vaccine delivery. In this way, chitosan microparticles, which have demonstrated to target the Peyer's patches efficiently in vivo, could be tested in vitro. The development of this M-cells model facilitates the optimization of the microparticles in order to target them even more efficiently to the M-cells in the gut. In this study, the integrity of the human M-cell model was investigated by determining the transepithelial electrical resistance (TEER), 14C-mannitol transport and morphology using scanning electron microscopy. The uptake of particles was investigated by measuring transport of both fluorescently labeled microspheres (Fluospheres) and chitosan microparticles using flowcytometry. No discontinuities or abnormalities could be found in the co-culture. Scanning electron microscopy showed that morphologically different cells were present in the human M-cell model. Both commercially available Fluospheres (size 0.2 microm) and chitosan microparticles (size 1.7 microm) for oral vaccine delivery were transported at a significantly higher amount by the human M-cell model compared to the transport by the Caco-2 cell monoculture. Since chitosan microparticles were proven to be taken up by Peyer's patches in mice as well, this human M-cell model is able to predict the M-cell uptake of microparticles for oral vaccine delivery. This M-cell model is a new tool, which can be used to scan, develop and optimize microparticles for oral vaccine delivery. Since the M-cell uptake can now be studied in vitro, the targeting of these cells can be studied more efficiently and can now be done in cells from human origin.

The nonhuman primate as a model of developmental immunotoxicity

Macaques are well suited for preclinical testing of biopharmaceutics due to reproductive and developmental similarities with humans. In order to characterize ontogeny of the immune system in this model, we studied lymphocyte and antigen-presenting cell populations in developing lymphoid tissues of rhesus macaque fetuses during the second and third trimesters [gestation days (GD) 75-145, term 165 days]. Systemic lymphoid tissues (thymus, spleen and lymph nodes, and intestinal tissue) were examined for morphology and cell surface markers by immunohistochemistry. Lymphocytes were further characterized by flow cytometry for differentiation markers. Splenic tissue from early second trimester fetuses was populated mainly by CD20+ B cells while the thymus contained large numbers of CD3+ T cells. In the late second trimester (day 80), approximately equal populations of B and T cells were present in both tissues and numerous dendritic cells (p55+) were present in the intestinal lamina propria. By the second trimester, the rhesus macaque fetal lymphoid system is well developed. Analysis of lymphoid organs from retinoic acid-treated fetuses indicated that the T-cell (thymus)-dependent compartment of the spleen white pulp in specimens with thymic aplasia showed a reduction in size and proportion of CD3+ T cells compared to controls. Our findings indicate that RA-induced thymic defects result in disrupted development of the splenic T-cell-dependent compartment.