Dietary phosphorus and an inflammatory challenge affect performance and immune function of weanling pigs

Ninety-six 3-wk-old pigs (6.3+/-0.12 kg initial BW) were allotted to one of eight treatments based on BW and litter origin to determine the effect of dietary phosphorus and an inflammatory challenge on performance and immune function. Four corn-soybean meal-based treatment diets were formulated to contain 0.16, 0.24, 0.32, or 0.40% available P. Monocalcium-dicalcium phosphate was used as the supplemental P source. The Ca:available P ratio was maintained at 2:1. To challenge the pigs, half of the pigs in each dietary treatment were injected i.m. with E. coli lipopolysaccharide (200 microg/kg of BW) on d 7 and 14. This resulted in a 2 x 4 factorial arrangement of treatments. Average daily gain for the 35-d study was increased linearly (P < 0.01) by increasing supplemental P. Average daily gain and ADFI were decreased (P < 0.05) by lipopolysaccharide injection. Serum P concentrations increased linearly (P < 0.01) with increasing supplemental P. Antibody titers to the injection of sheep red blood cells and ovalbumin on d 21 decreased linearly (P < 0.10) by increasing supplemental P. In vitro blastogenic response of lymphocytes to phytohemagglutinin (PHA) on d 25 was increased linearly (P < 0.05) by increasing supplemental P. Blastogenic response of lymphocytes to pokeweed mitogen on d 25 was not affected. On d 31, skinfold thickness 6 h following an intradermal injection of PHA was increased quadratically (P < 0.07) by increasing supplemental P. There were no P x lipopolysaccharide interactions for any immune response measure. In conclusion, increasing supplemental P increased ADG and enhanced cell-mediated immune response but decreased humoral immune response.

T cell activation, apoptosis and cytokine dysregulation in the (co)pathogenesis of HIV and pulmonary tuberculosis (TB)

Immune parameters were compared in four groups of Ugandan subjects: HIV-and HIV+ adult patients with active pulmonary TB (HIV- PTB n = 38; HIV+ PTB n = 28), patients with HIV infection only (n = 26) and PPD+ healthy controls (n = 25). Compared with healthy controls, CD4 and CD8 T cells from patients with HIV and/or PTB expressed more activation markers (HLA-DR, CD38); their CD8 T cells expressed more CD95 (pre-apoptosis) and less CD28 (co-stimulatory receptor). Peripheral blood mononuclear cells (PBMC) of patients with either HIV or PTB were impaired in interferon-gamma (IFN-gamma) production upon antigenic stimulation. PTB (with or without HIV) was characterized by monocytosis, granulocytosis, increased transforming growth factor-beta 1 production and PPD-induced apoptosis. In vivo CD4 T cell depletion, in vitro increased spontaneous CD4 T cell apoptosis and defects in IFN-gamma responses upon mitogenic stimulation were restricted to HIV+ subjects (with or without PTB). Overlapping and distinctive immune alterations, associated with PTB and HIV, might explain mutual unfavourable influences of both diseases.

Shipment impairs lymphocyte proliferative responses to microbial antigens

Lymphocyte proliferation assays (LPAs) are widely used to assess T-lymphocyte function of patients with human immunodeficiency virus infection and other primary and secondary immunodeficiency disorders. Since these assays require expertise not readily available at all clinical sites, specimens may be shipped to central labs for testing. We conducted a large multicenter study to evaluate the effects of shipping on assay performance and found significant loss of LPA activity. This may lead to erroneous results for individual subjects and introduce bias into multicenter trials.

Activated self-MHC-reactive T cells have the cytokine phenotype of Th3/T regulatory cell 1 T cells

In the present study, we show that human self-MHC-reactive (autoreactive) T cell clones are functionally distinct from Ag-specific T cell clones. Self-MHC-reactive T cells exhibited helper function for B cell Ig production when cultured with non-T cells alone, and they exhibit suppressor function when cultured with PWM- or rCD40 ligand (rCD40L)-activated non-T cells, whereas tetanus toxoid (TT)-specific clones exhibited only helper function in the presence of TT with or without PWM or rCD40L. Addition of neutralizing Abs to the cultures showed that the suppression was mediated by TGF-beta but not by IL-10 or IFN-gamma. The self-MHC-reactive clones also inhibited proliferation of primary CD4+ T cells and TT-specific T cell clones, but in this case the inhibition was mediated by both IL-10 and TGF-beta. In further studies, the interactions between self-MHC-reactive T cell clones and non-T cells that led to suppressor cytokine production have been explored. We found that prestimulation of non-T cells for 8 h with PWM or for 48 h for rCD40L results in non-T cells capable of inducing self-MHC-reactive T cell to produce high levels of TGF-beta and IL-10. In addition, these prestimulation times coincided with peak induction of HLA-DR and costimulatory B7 molecule (especially CD86) expression on B cells. Finally, addition of CTLA-4/Fc or blocking F(ab')2 anti-CTLA-4 mAb, plus optimally stimulated non-T cells, to cultures of self-MHC-reactive clones inhibited the induction of TGF-beta but not IL-10 or IFN-gamma production. In summary, these studies show that activated self-MHC-reactive T cells have the cytokine phenotype of Th3 or T regulatory cell 1 and thus may be important regulatory cells that mediate oral and peripheral tolerance and prevent the development of autoimmunity.

Cytokine secretion by peripheral blood mononuclear cells from cows infected with Mycobacterium paratuberculosis

OBJECTIVE

To compare cytokine secretion patterns of peripheral blood mononuclear cells (PBMC) from healthy cows and cows subclinically and clinically infected with Mycobacterium paratuberculosis.

ANIMALS

5 noninfected cows, 6 cows with subclinical paratuberculosis, and 4 cows with clinical paratuberculosis.

PROCEDURE

PBMC were isolated, and concentrations or activities of secreted interleukin (IL)-1, IL-2, IL-6, tumor necrosis factor (TNF), and interferon-gamma (IFN-gamma) were measured after in vitro stimulation of cells with concanavalin A (ConA), lipopolysaccharide (LPS), or a whole-cell sonicate of M paratuberculosis (MpS). Proliferative responses of PBMC were also determined after stimulation with ConA, phytohemagglutinin, pokeweed mitogen (PWM), or MpS.

RESULTS

After stimulation with ConA, cells from subclinically infected cows secreted significantly more, and cells from clinically infected cows secreted significantly less, IFN-gamma, compared with cells from control cows. Cells from cows with subclinical paratuberculosis produced significantly more TNF and IFN-gamma in response to MpS than cells from the other 2 groups. Stimulation of PBMC from subclinically infected cows with ConA or MpS resulted in significantly higher proliferative responses, compared with cells from control and clinically infected cows. In contrast, clinically infected cows had significantly higher proliferative responses to PWM than cells from the other 2 groups.

CONCLUSIONS AND CLINICAL RELEVANCE

A decrease in T-cell responses to mitogens or MpS was observed in cows clinically infected with M paratuberculosis, compared with subclinically infected cows, suggesting that activated T cells may delay the progression of paratuberculosis.

Early suppression of lymphoproliferative response in dogs with natural infection by Leishmania infantum

Dogs are the domestic reservoirs of zoonotic visceral leishmaniasis caused by Leishmania infantum. Early detection of canine infections evolving to clinically patent disease may be important to leishmaniasis control. In this study we firstly investigated the peripheral blood mononuclear cell (PBMC) response to leishmanial antigens and to polyclonal activators concanavalin A, phytohemagglutinin and pokeweed mitogen, of mixed-breed dogs with natural L. infantum infection, either in presymptomatic or in patent disease condition, compared to healthy animals. Leishmania antigens did not induce a clear proliferative response in any of the animals examined. Furthermore, mitogen-induced lymphocyte proliferation was found strongly reduced not only in symptomatic, but also in presymptomatic dogs suggesting that the cell-mediated immunity is suppressed in progressive canine leishmaniasis. To test this finding, naive Beagle dogs were exposed to natural L. infantum infection in a highly endemic area of southern Italy. Two to 10 months after exposure all dogs were found to be infected by Leishmania, and on month 2 of exposure they all showed a significant reduction in PBMC activation by mitogens. Our results indicate that suppression of the lymphoproliferative response is a common occurrence in dogs already at the beginning of an established leishmanial infection.

Comparison of erythropoietic response to androgen in young and old senescence accelerated mice

In this study, to clarify whether the functional capacity of hemopoietic progenitor cells and the micro-environment of aged mice are identical with those of the young, we investigated the changes in the number of hemopoietic progenitor cells and the production of regulatory cytokines from splenic cells as well as changes in the serum levels of cytokine in senescence-accelerated mice (SAM) after administration of 19-nandrolone decanoate (19-ND), a synthetic androgenic anabolic steroid. 19-ND induced an increase in erythroid colony-forming units (CFU-E), erythroid burst-forming units (BFU-E), and granulocytic-macrophage committed progenitor cells (CFU-GM) in bone marrow and spleen; especially remarkable increases were observed in the splenic CFU-E in both young and old mice. Antigen expression analysis of hemopoietic organs revealed that total TER-119+ cells per spleen of young and old mice with androgen treatment rose 2.6- and 3.2-fold over their respective control values. The responsiveness of hemopoietic progenitor cells to androgen did not change with age. Injection of 19-ND into young and old mice markedly enhanced the erythropoietin levels but not IL3 and GM-CSF levels in the serum of both groups. Cytokine production assessed by pokeweed mitogen-stimulated spleen condition medium showed an age-related decline. Androgen treatment could not influence IL-3 and GM-CSF production of spleen. These findings suggest that the spleen of both old and young mice served as the major site of regenerative repopulation of hemopoietic progenitors, especially the late erythroid progenitors in 19-ND-treated mice. The proliferative reserve of erythropoiesis with androgen treatment in aged mice was not reduced more than that in treated-young mice.

Balance of Th1/Th2 cytokines in thyroid autoantibody synthesis in vitro

Thyroid-infiltrating lymphocytes spontaneously synthesize IgG class thyroid autoantibodies while blood lymphocytes require activation to produce the same autoantibodies. Surprisingly, the stimulus commonly used to induce autoantibodies by blood lymphocytes, Pokeweed mitogen (PWM), inhibits autoantibody synthesis by thyroid lymphocytes. To address this dichotomy, we investigated the Th1: Th2 cytokine balance in relation to thyroid peroxidase (TPO) autoantibody production in cultures of thyroid, lymph node and blood lymphocytes. The characteristic PWM effect on TPO autoantibody production by thyroid and blood lymphocytes (10 day cultures) was confirmed. Cytokine measurements in these cultures revealed that PWM increased IFN-gamma production by thyroid, lymph node and blood lymphocytes. However, PWM enhanced IL-4 levels in lymphocytes from blood and lymph node but not in thyroid lymphocytes. Moreover, the IL-4: IFN-gamma ratios in short- and long-term cultures were higher for PBMC and lymph node lymphocytes than for thyroid lymphocytes. In summary, PWM shifts the cytokine balance towards Th2 for blood lymphocytes and towards Th1 for thyroid lymphocytes. The shift towards Th1 in the target organ is associated with reduced autoantibody synthesis. Our observations suggest that "immune deviation" towards Th2 as a form of therapy in Graves' disease could project the patient from the frying pan into the fire.

Comparison of enterovirus-specific cellular immunity in two populations of young children vaccinated with inactivated or live poliovirus vaccines

Enterovirus-specific cellular immunity was studied in Estonian and in Finnish children at the age of 9 months. The aim was to evaluate the level of responsiveness in two neighbouring countries with different poliovirus immunization practices and striking differences in the incidence of insulin-dependent diabetes mellitus (IDDM), a disease in which early enterovirus infections are an aetiological risk factor. The Estonian children immunized with live attenuated polio vaccine had stronger T cell responses to coxsackievirus B4 and poliovirus type 1 when compared with Finnish children immunized with inactivated polio vaccine (median stimulation indices 10.4 and 6.3 in Estonian children and 1.9 and 2.9 in Finnish children, respectively; P < 0.05). Lymphocytes stimulated by poliovirus type 1 antigen expressed interferon-gamma (IFN-gamma) mRNAs, which strongly correlated with the level of proliferation responses. Lymphocytes of Estonian children had a tendency towards stronger expression of IFN-gamma upon poliovirus challenge when compared with Finnish children. The number of children who had experienced coxsackievirus B infections, as determined by the presence of neutralizing antibodies, did not differ between Estonian and Finnish children. The results show that Finnish children have weaker cellular immunity against enteroviruses at the age of 9 months compared with Estonian children at the same age. This is most probably due to the difference in polio vaccination schedules; in Estonia live poliovirus vaccine is used and given at earlier ages than the inactivated vaccines in Finland. This leads to stronger T cell immunity which cross-reacts with other enterovirus serotypes. This may explain the lower incidence of IDDM in Estonia by providing effective protection against diabetogenic enterovirus strains in Estonian children.

Lymphocyte responses to mitogens and rickettsial antigens in sheep experimentally infected with Ehrlichia (Cytoecetes) phagocytophila

Infection of sheep with Ehrlichia (Cytoecetes) phagocytophila, the causative agent of tick-borne fever (TBF), was characterised by a significant reduction in lymphocyte reactivity to the mitogens phytohaemagglutinin, concanavalin A, pokeweed mitogen and Escherichia coli lipopolysaccharide during the period of rickettsiaemia. The addition of the prostaglandin inhibitor, indomethacin, or the nitric oxide inhibitor, N(G)-monomethyl-L-arginine, had no significant effect on the suppressive effects of E. phagocytophila on lymphocyte reactivity to the mitogens. However, peripheral blood lymphocytes obtained from primed sheep proliferated in the presence of live or heat-inactivated E. phagocytophila. Antigen-specific proliferation was detected in lymphocytes samples obtained 11 to 21 days post-inoculation with E. phagocytophila.

Kinetic and immunohistochemical characteristics of mitogen-induced cutaneous hypersensitivity in chickens selected for antibody responsiveness

Mitogen-induced cutaneous hypersensitivity was evaluated in chickens selected for high and low antibody responses to SRBC, and in a random bred control line. Wing web swelling responses were found after subcutaneous administration of phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), and Escherichia coli lipopolysaccharide (LPS), respectively, in all three lines. All mitogens induced significant acute 4 h wing web swelling responses, followed by a significant (classical) late 24 h wing web swelling response. The 4 h responses were significantly lower in the L line, whereas a tendency for lower responses at 24 h in the L line was found as well. Immunohistochemical evaluation of the early and late wing web swelling responses revealed extravascular localisation of leukocytes at 24 h after sensitization with mitogens, which consisted of CD4+ cells, CD8+ cells, TCR-1+ cells, and heterophils, but no B cells, whereas the 4 h swelling response was primarily characterized by oedema. Cutaneous hypersensitivity either initiated by T-cell mitogens as well as B-cell mitogens may depend for an important part on the rapid induction of local homing of lymphocytes towards the sensitizing agent, which may be mediated by an acute local expression of molecules with chemo-attractive capacities. Interpretation of cellular immunity responses in vivo such as delayed-type hypersensitivity should therefore incorporate oedema-initiating characteristics of sensitizing agents. The relationship between the magnitude of cutaneous hypersensitivity to mitogens and selection for antibody responsiveness is discussed.

Psoriasis patients have T-cells with reduced responsiveness to common mycobacterial antigens

Heparinised blood samples were obtained from 20 patients with chronic plaque psoriasis and from 13 age-matched healthy controls. After preliminary titration, mononuclear cells separated over Ficoll-Tryoson were cultured for 5 days with 10 microg ml(-1) of 15 mycobacterial preparations, or with pokeweed mitogen and concanavalin A. Stimulation indices were determined for each reagent and means were determined for patients and controls. Results for patients showed a striking reduction of responsiveness to mycobacteria, apparently due to loss of responses to group i, common mycobacterial antigens, and no differences in responses to mitogens. These observations relate psoriasis to certain other diseases, notably mycobacterial infections, rheumatoid arthritis, Chagas' disease and human immunodeficiency virus infection. The observations may be relevant to the aetiology of psoriasis, and to potential immunotherapy for the disease.

HIV type 1 envelope glycoprotein 120 carboxy-terminal peptide-induced human T cell lines selectively suppress heterogeneous proliferative T cell responses to soluble antigens

It has been proposed that the highly conserved human immunodeficiency virus type 1 (HIV-1) envelope gp120 carboxy-terminal sequence, TKAKRRVVEREKR (CT120), may represent a functional mimic of the human leukocyte antigen (HLA) class II DR beta-chain third hypervariable region (HVR3) sequence motif located at position 69-81. Presentation of this potentially pathogenic fragment by HLA class I and/or II molecules, in a manner analogous to the indirect pathway of allorecognition, may induce both widespread cellular activation and also break self-tolerance, resulting in the selective and progressive anti-self HLA class II-directed immune suppression, which is a central feature of HIV-1 infection and the associated acquired immune deficiency syndrome (AIDS). To investigate the functional role of the HIV-1 gp120 C-terminal fragment T cell lines (TCLs) were raised from three healthy HIV-1-seronegative subjects at low risk of HIV-1 exposure, by repeated stimulation with a short synthetic 13-mer CT120 peptide in vitro. Graded concentrations (10[3] to 5 x 10[4]) of CT120 TCLs suppressed the primary 6-day proliferation of autologous PBMCs in response to the soluble antigens tetanus toxoid (TT) and purified protein derivative (PPD). In contrast, CT120 TCLs demonstrated no suppressive effect on 3-day phytohemagglutinin (PHA), concanavalin A (ConA), and pokeweed mitogen (PWM) mitogenic responses. Fractionation of CT120 TCLs into highly purified CD4+ and CD8+ T cell subsets demonstrated that the CD8+ T cell fraction mediated the suppressor effector function. HLA restriction analysis revealed a complex pattern as both anti-HLA class II DR and anti-HLA class I (A, B, C) MAbs inhibited proliferation of oligoclonal CD8+ CT120 TCLs. Strategies aimed at specifically inhibiting such putative immunopathogenic HIV-1-encoded T cell epitopes may be an important consideration for development of future HIV-1 immunotherapy.

Analysis of partial variance to control for day-to-day variability in functional immune tests in depression

Recently, analysis of partial variance (APV) was proposed as a technique to control for day-to-day variance in mitogen-induced lymphoproliferative responses whereby data obtained from controls, run in the laboratory on the same day, are used as covariates in regression analysis. In order to check the utility of the APV method in the interpretation of functional immune tests, we have reanalyzed lymphoproliferative responses in experimental subjects with depression (n = 38) stimulated by phytohemagglutinin (PHA), pokeweed mitogen (PWM) and concanavalin A (Con A) in relation to responses obtained in laboratory controls. There were no significant relationships between the depressed patients' and laboratory controls' lymphoproliferative responses to PHA, PWM or Con A. Controlling for day-to-day variation by means of regression analysis did not significantly alter the significant relationships between the patients' lymphoproliferative responses and clinical variables, such as depressive classification and severity of illness. It is argued that the APV method may not be used to adjust for an inappropriately high day-to-day variability in immune assays.

Inhibitors of dipeptidyl peptidase IV induce secretion of transforming growth factor-beta 1 in PWM-stimulated PBMC and T cells

Various studies have shown that the membrane ectoenzyme dipeptidyl peptidase IV (DP IV; CD26), expressed on T, natural killer (NK) and B cells in the immune system, is involved in the regulation of DNA synthesis and cytokine production. We show that the specific DP IV inhibitors Lys[Z(NO2)]-thiazolidide, Lys[Z(NO2)]-piperidide, and Lys[Z(NO2)]-pyrrolidide inhibit DNA synthesis as well as production of interleukin-2 (IL-2), IL-10, IL-12, and interferon-gamma (IFN-gamma) of pokeweed mitogen (PWM)-stimulated purified T cells. Most importantly, these inhibitors induce a three- to fourfold increased secretion of latent transforming growth factor-beta 1 (TGF-beta 1) by PWM-stimulated peripheral blood mononuclear cells (PBMC) and T cells, as measured with a specific TGF-beta 1 enzyme-linked immunosorbent assay and in the Mv1Lu bioassay. As we could demonstrate previously, TGF-beta 1 exhibits the same inhibitory effects as DP IV inhibitors on DNA synthesis and cytokine production (Cytokine 1994, 6, 382-8; J Interferon Cytokine Res 1995, 15, 685-90). A neutralizing chicken anti-TGF-beta 1 antibody was capable of abolishing the DP IV inhibitor-induced suppression of DNA synthesis of PWM-stimulated PBMC and T cells. These data suggest that TGF-beta 1 might have key functions in the molecular action of DP IV/CD26 in regulation of DNA synthesis and cytokine production.

Suppression of pokeweed mitogen-driven human IgM and IgG responses by the hydroxylamine of sulfamethoxazole

OBJECTIVE

To determine the effect(s) of reactive sulfonamide metabolites on antibody production by human lymphocytes.

METHODS

Human peripheral blood cells (PBMCs) were isolated from control volunteers and incubated with the hydroxylamine of sulfamethoxazole (SMX H/A), a reactive metabolite of the most commonly used sulfonamide, in increasing concentrations. PBMCs were then stimulated to produce antibody with pokeweed mitogen. After incubation for 8 days, concentrations of IgG and IgM were determined in supernatant using an ELISA assay.

RESULTS

Production of both IgG and IgM was significantly suppressed by sub-lethal concentrations of SMX H/A in a concentration-dependent fashion (p < 0.05). Suppression was more marked for IgM production (maximal decline to 80% of baseline antibody production) than for IgG production (maximal decline to 57% of baseline antibody production). No suppression was seen when cells were incubated with sulfamethoxazole in concentrations up to 400 microM. This suppression was not related to changes in cell viability; at a concentration of 25 microM of SMX H/A, IgM and IgG concentration were reduced by 47 +/- 8.7% and 73 +/- 7.2%, while cell viability (percentage of live cells) was 93 +/- 5%. Suppression was time-dependent, increasing over the incubation periods to reach a plateau after 2 h of incubation.

CONCLUSION

Sulfonamide reactive metabolites, in concentrations which are achieved during therapy, suppress antibody production by PWM-stimulated human cells. This may explain, in part, the alterations in immunity associated with hypersensitivity reactions to the sulfonamides. This may also have implications for patients receiving sulfonamide therapy and concurrent immunosuppressive therapy.

Importance of combined treatment with IL-10 and IL-4, but not IL-13, for inhibition of monocyte release of the Ca(2+)-binding protein MRP8/14

Expression of the two myeloic related proteins MRP8 and MRP14 is restricted to distinct stages of monocytic differentiation. Heterodimeric MRP8/14 complexes (27E10 antigen) have been shown to represent their biologically active forms. In this study, we investigated the effects of Th2-cytokines on release of these proteins from freshly obtained blood monocytes and monocytes cultured for 7 days in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF). Monocytes were stimulated with pokeweed mitogen (PWM) in the presence or absence of interleukin-13 (IL-13), IL-4 and IL-10, and secretion of MRP8, MRP14 and MRP8/14 was assessed by using a sandwich enzyme-linked immunosorbent assay system. Peripheral monocytes secreted significantly increased amounts of MRP14 and MRP8/14 but not MRP8 under stimulation with PWM. IL-10 and IL-4, but not IL-13, down-regulated the PWM-stimulated MRP8/14 secretion in a dose-dependent manner. Maximal inhibition required that IL-10 and IL-4 be added up to 1 h before or simultaneous with PWM. A combination of IL-10 and IL-4 even at suboptimal concentrations significantly suppressed protein secretion much more than using IL-10 or IL-4 at a doubled concentration alone. Peripheral monocytes cultured for 7 days in the presence of GM-CSF showed two-to threefold higher protein levels compared with freshly obtained blood monocytes but responded inefficiently to either IL-4, IL-13, or IL-10 alone. However, treatment with IL-10 in combination with IL-4 but not IL-13 strongly suppressed MRP14 and MRP8/14 release by these cells. The unresponsiveness of 7-day-cultured blood macrophages suggests that more differentiated and activated cells may lose their ability to respond to anti-inflammatory cytokines. Combined cytokine treatment may therefore more effectively control the progression of chronic inflammatory processes.

Desialylation of T lymphocytes overcomes the monocyte dependency of pokeweed mitogen-induced T-cell activation

Activation of T lymphocytes by pokeweed mitogen (PWM) is strictly monocyte (Mo)-dependent and results in T-cell mitogenesis and interleukin-2 (IL-2) secretion, coupled with an inability to utilize IL-2 due to an impaired expression of functional IL-2 receptor (IL-2R). Such IL-2R impairment could arise in PWM-activated T cells themselves or, alternatively, be the result of Mo-derived influences, as it is known that PWM binds Mo strongly and does not or poorly binds lymphocytes, and Mo becomes rapidly destroyed in PWM-stimulated cultures of blood mononuclear cells or T cells plus Mo. The present study investigated these possibilities. The results show for the first time that desialylation of T lymphocytes strongly increases their PWM-binding capacity and, in addition, overcomes the Mo requirement for PWM to induce T-cell mitogenesis and IL-2 secretion. Such secreted IL-2 levels were even higher that those found in cultures of Mo-dependent PWM-activated T lymphocytes but similarly to the latter, PWM-activated desialylated purified T lymphocytes exhibited negligible high-affinity IL-2 binding capacity and an inability to utilize the IL-2 they produced. These effects were not due to desialylation itself, as indicated by data obtained with peanut agglutinin, a lectin that becomes strongly reactive with desialylated T lymphocytes. The data clearly indicate the existence of PWM-related events capable of impairing the expression of functional IL-2R without affecting IL-2 secretion, and indicate that such events are due to mechanisms arising at the level of PWM-activated T cells themselves.

Studies of proliferative responses by long-term-cryopreserved peripheral blood mononuclear cells to bacterial components associated with periodontitis

Freezing techniques provide a means for repeating and extending immunological assays with frozen aliquots of an individual's peripheral blood mononuclear cell fraction. Lymphocytes which are stored frozen for a limited time retain their ability to respond to polyclonal B-cell activators, mitogens, and antigens of dental interest. Our studies extend these previous findings by determining lymphocyte functional activity following frozen storage for up to 100 weeks. In addition, the autologous immune response was measured by spontaneous lymphocyte proliferation following 0, 1, 40, and 60 weeks of frozen storage. Peak responses for all individuals occurred at day 7 of incubation. The lymphocyte proliferative response to the superantigens toxic shock syndrome toxin-1 (TSST-1) and Staphylococcus enterotoxin A (SEA) were not changed after 100 weeks of frozen storage. Maximum responses varied among the individuals but occurred at equivalent stimulator concentrations. However, slopes generated from data obtained following 0, 4, 13, 20, 30, 50, 88, and 100 weeks of frozen storage showed no significant deviation from zero (P > 0.05) for all individuals tested. After 100 weeks of storage, the total changes in proliferative activity (counts per minute per week) were -2.1% +/- 16.8% and -5.5% +/- 17.0% for TSST-1 and SEA, respectively. The lymphocyte proliferative responses to pokeweed mitogen, concanavalin A, and sonicates of two periodontal pathogens (Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans) following frozen storage were similar to those with TSST-1 and SEA. These results indicate that peripheral blood mononuclear cells stored frozen may serve as appropriate controls to monitor changes in the disease state long-term periodontal treatment.

In vitro cytokine production and phenotype expression by blood mononuclear cells from umbilical cords, children and adults

Age related differences in immunological reactions include variations in the in vitro functions of blood mononuclear cells (MNC). In an attempt to understand the mechanism behind these differences we examined age related differences in the phenotype profiles of MNC in parallel with the in vitro production of interleukin IL-6, tumour necrosis factor alpha (TNF alpha) and interferon gamma (IFNg) in neonates, children and adults. In cultures without added polyclonal activators IL-6 and TNF alpha levels in children were 3-6 times higher than those of umbilical cords and adults. However, using optimal in vitro stimulation (E. coli lipopolysaccharide (LPS), phytohaemmagglutinin or pokeweed mitogen (PWM)) no significant differences in the levels of these cytokines were observed. The levels of IFNg in PWM driven cultures followed a different pattern with comparable levels in children and adults, and unmeasurable levels in cord blood MNC. Flow cytometry analysis of the phenotypic distribution of MNC revealed age related differences in the expression of CD3, CD4, CD8, CD14, CD19, CD45RA, CD45R0, CD2, LFA-1, ICAM-1 and LFA-3. Correlation studies did not indicate that the observed differences in cytokine production could be ascribed to differences in the frequency of monocytes, T cells or B cells. The TNF alpha levels in suboptimally stimulated cultures correlated negatively with the expression of LFA-3 and positively with CD45RA, while IFNg correlated positively with CD2, LFA-1, CD45R0 and CD8. In conclusion, the study provides evidence of age related differences in the production of TNF alpha, IL-6 and IFNg among neonates, children and adults. These differences may to some extent be caused by differences in the expression of cell surface molecules involved in cellular interactions and signalling.

Immunoregulatory properties of IL-13 in patients with inflammatory bowel disease; comparison with IL-4 and IL-10

Activated monocytes with increased expression of proinflammatory cytokines play a major role in inflammatory bowel disease (IBD). Immunoregulatory cytokines such as IL-4 and IL-10 can effectively suppress the proinflammatory response of activated monocytes. IL-13 is a recently described antiinflammatory agent in vitro. The aim of our study was to determine the in vitro immunosuppressive capacity of IL-13, IL-4 and IL-10 in patients with IBD. Peripheral blood monocytes were isolated from 27 patients with ulcerative colitis (UC), 27 patients with Crohn's disease (CD) and 16 healthy controls. Cells were stimulated with pokeweed mitogen (PWM) after treatment with IL-13, IL-4 and IL-10, and secretion of IL-1beta, tumour necrosis factor-alpha (TNF-alpha) and IL-6 was assessed using sandwich ELISA systems. Peripheral blood monocytes secreted significantly increased amounts of TNF-alpha and IL-6 under stimulation with PWM in patients with CD, while UC patients showed significantly elevated levels of IL-1beta. The antiinflammatory cytokines IL-13, IL-4 and IL-10 were all capable of inhibiting monocyte secretion of IL-1beta in a dose-dependent manner. With regard to IL-13 and IL-4, there was no significant suppression of TNF-alpha and IL-6 in patients with active IBD. By contrast, IL-10 was able to down-regulate all proinflammatory cytokines in active IBD as well as in controls. Proinflammatory cytokines from patients with inactive IBD could be significantly down-regulated by all three immunoregulatory cytokines. The inhibitory effect of IL-13 on TNF-alpha and IL-6 production in differentiated macrophages was diminished in IBD patients, as well as in controls. In disease controls we also observed a reduced inhibition of TNF-alpha and IL-6 after treatment with IL-13. In conclusion, the antiinflammatory activity of IL-13 is partially reduced in patients with active IBD. The hyporesponsiveness of activated and differentiated monocytes to IL-13 and IL-4 does not seem to be a disease-specific phenomenon.

Polyclonal immunoglobulin response of thymic, hepatic and splenic lymphocytes from fetal, germ-free and conventionally reared pigs to different B-cell activators

Immunoglobulin (Ig) response to different polyclonal B-cell activators was measured by ELISA in cell culture media of thymocytes, splenocytes and liver cells isolated from pig fetuses, 8-d-old germ-free piglets and conventionally reared pigs. Both in fetal and in postnatal life polyclonally stimulated lymphocytes were found to produce predominantly the IgM isotype; the first IgM formation was detected in 50-d-old fetal liver (gestation in pigs lasts 114 d). Surprisingly, 73-d-old fetal thymic cells were shown to be induced to Ig synthesis and secretion. In contrast to splenocytes of the same age, which secreted exclusively IgM, fetal thymocytes produced IgM, IgG and IgA. Polyclonally stimulated splenic cells as compared with thymic cells started to produce IgA later in fetal ontogeny, whereas the IgG response was not detectable in splenic cell culture media during the whole embryonal development and appeared only after birth. The earliest and the highest Ig stimulation was found after cultivation of lymphocytes with Nocardia delipidated cell mitogen. Interestingly, the moderate stimulatory effect of 65-kDa heat shock protein (Hsp-65) in polyclonal IgM response of fetal splenocytes was observed. We showed that thymic B lymphocytes represent probably the first maturing B cell population detectable in fetal life, which is able to differentiate after polyclonal stimulation into IgM as well as IgA and IgG producing cells.

Cytokine production by cats infected with feline immunodeficiency virus: a longitudinal study

The immune responsiveness of cats naturally or experimentally infected with feline immunodeficiency virus (FIV) was studied. Peripheral blood mononuclear cells (PBMC) from naturally infected, symptomatic animals displayed depressed proliferation and interleukin-2 (IL-2) production in response to mitogens, which was accompanied by a significant increase in IL-1, IL-6 and tumour necrosis factor (TNF) production. Longitudinal studies were performed over a period of 4 years in experimentally infected animals. The responses of cells from these cats to concanavalin A (Con A) were consistently less than those from uninfected cats throughout the period but, owing to variation between cats, were significantly lower on only a few occasions. By contrast, the responses of cells to pokeweed mitogen (PWM) were severely affected and declined progressively throughout the 4-year period. In general, responses to Con A but not PWM could be restored by the addition of exogenous IL-2. The decline in immune responsiveness was concurrent with a decline in feline (f)CD4+ cells and an inversion in the CD4:CD8 ratio. Peak production of IL-1, IL-6 and TNF coincided with periods of depressed immune responses. Additionally, immunodeficient responses and elevated levels of proinflammatory cytokines were concurrent with the presence of clinical signs. We conclude that, like human immunodeficiency virus (HIV), FIV infection results in significant perturbation of the immune response. Responses to PWM appear to correlate with disease progression which suggests that the CD3 pathway is affected in the earlier stages of the disease and that additional activation pathways such as CD2 may not be affected until the animal enters the acquired immune deficient syndrome (AIDS) stage of the disease.

Mechanisms of eosinophilia in mice infested with larval Haemaphysalis longicornis ticks

Infestation of larval Haemaphysalis longicornis ticks induced a threefold increase of eosinophils in the peripheral blood of normal WBB6F1- +/+ mice 2 days after tick infestation. In genetically mast cell-deficient WBB6F1- W/Wv mice, a threefold increase of blood eosinophils was observed 6 days after the tick infestation. However, marked infiltration of eosinophils was detected in the tick infestation sites of the WBB6F1- +/+ mice but not the WBB6F1- W/Wv mice. When the mast cell deficiency of WBB6F1- W/Wv mice had been rescued locally by intradermal injections of WBB6F1- +/+ mouse-derived cultured mast cells, a rapid increase of blood eosinophils and tissue infiltration of eosinophils were revealed following tick infestation. The intravenous (i.v.) injection of immune spleen or lymph node cells obtained from WBB6F1- +/+ mice 10 days after tick infestation led to significant eosinophilia in naive recipient mice. Treatment with anti-Thy-1.2 or anti-CD4 monoclonal antibody (mAb) and complement (C) completely abolished the eosinophilia; the early response (2 days after tick challenge) is dependent on mast cells at the feeding site, and the late response (6 days after tick challenge) is dependent on T lymphocytes. Since amplified interleukin-5 (IL-5) cDNA was detectable in the spleen cells 4 days after tick infestation, the late response might be mediated by IL-5. The infiltration of eosinophils at the feeding site of skin appeared to be dependent on mast cells.