Cellular hypersensitivity and immunity: conceptual changes in last decade

Diet-induced obesity results in impaired oral tolerance induction

INTRODUCTION

Obesity increases the risk of several diseases, such as type 2 diabetes mellitus and cardiovascular disease. Obesity also affects the immune system. When dietary lipids are transported via the lymphatics, they pass the mesenteric lymph nodes (mLNs). In these secondary lymphoid organs, immune responses towards pathogens are generated, or tolerance against harmless antigens is induced.

METHODS

In this study, the effects of diet-induced obesity (DIO) on mLN induced oral tolerance induction were examined in C57BL/6NCrl mice. Therefore, mice were fed a high-fat or a low-fat diet for 14 weeks. After 10 weeks of feeding oral tolerance induction started, ending up in measuring the delayed-type hypersensitivity reaction, the cell subset composition and cytokine expression.

RESULTS

We detected an impaired oral tolerance induction during DIO, but changes were reversible after switching the feed to standard chow. Thus, the altered immunological function of mLNs depends on the intake of dietary lipids. Additionally, our results show an influence of the microenvironment on the development of oral tolerance during DIO as oral tolerance was induced in transplanted peripheral lymph nodes.

CONCLUSION

This indicates a functional influence of dietary lipids on stromal cells involved in immune system induction in the mLNs.

Murine Q Fever Vaccination Model Reveals Sex Dimorphism in Early Phase Delayed-Type Hypersensitivity Responses

Delayed-type hypersensitivity (DTH) responses to microbial vaccines and related components are a major roadblock for widespread licensing of whole cell vaccines such as that of Q fever. Q fever is a zoonotic disease caused by the intracellular bacterium Coxiella burnetii. The only currently licensed vaccine, Q-Vax^®, is a whole cell inactivated formulation that is associated with a potentially severe dermal post vaccination DTH response in previously sensitized individuals. To investigate the underlying immunologic mechanisms of this response and better represent the early-phase DTH response observed in humans, a murine sensitization and skin testing model was developed and employed. Female C57Bl/6J mice displayed the most robust early-phase DTH responses following sensitization and elicitation compared to their male counterparts and other mouse strains. Immunologic responses were measured within the skin, draining lymph nodes, and serum following both sensitization and elicitation with Q fever whole cell vaccines. Local immunologic responses in the dermis were characterized by inflammation primarily involving neutrophils, macrophages, and T cells. Secondary lymphoid organ profiling revealed distinct immunological signatures following both sensitization and elicitation with a sex-based dichotomy in T cell phenotypes and antigen presenting cell numbers. Beyond providing a post-Q fever vaccination DTH model that recapitulates early-phase DTH events, these data suggest that sex is a primary factor influencing the magnitude and composition of the ensuing response.

Evaluation of the immunomodulatory and anti-inflammatory activity of Bakuchiol using RAW 264.7 macrophage cell lines and in animal models stimulated by lipopolysaccharide (LPS)

Bakuchiol (BAK) has been reported to have a diverse pharmacological property as an antibiotic, anti-cancer, anti-hypolipidemic, anti-inflammatory and anti-convulsant agent. This study aimed to elucidate the immunomodulation and anti-inflammatory mechanism of bakuchiol using lipopolysaccharide stimulated RAW 264.7 macrophages and various animal models. The present study has shown that BAK significantly suppressed the pro-inflammatory cytokine expression in a dose-dependent manner and its oral administration significantly decreased delayed hypersensitivity responses as compared to control group. The assessment of immunomodulatory activity was carried out by the testing Hemagglutinating antibody (HA) titer, delayed type hypersensitivity (DTH) responses and phagocytic index by carbon clearance test. On the other hand, it showed significant decrease in circulating antibody titer and carbon clearance assay in a concentration-dependent manner. BAK has significantly potentiated the cellular immunity as well as humoral immunity by facilitating the footpad thickness responses in sheep RBCs in sensitized mice by significantly decreasing circulating antibody titer. Molecular studies revealed that BAK inhibited the activation of upstream mediator nuclear factor-κB by suppressing the phosphorylation of IκBα and p65. The responses were statistically significant as compared with the control (*p < 0.05, **p < 0.01).

Study on the impact of lead acetate pollutant on immunotoxicity produced by thiamethoxam pesticide

Objective:

The curtailed knowledge about neonicotinoids that it has low affinity for vertebrate relative to insect nicotinic receptors is a major factor for its widespread use assuming that it is much safer than the previous generation insecticides. But literature regarding effect of thiamethoxam (second generation neonicotinoid)on immune system is not available. Also, there might be chances of interaction of heavy persistent metals in the water table with these pesticides. So, this study was undertaken with the objective to find immunotoxic alterations of lead acetate after exposure with thiamethoxam in animal model.

Materials and Methods:

For this albino mice were randomly divided into 6 groups (numbered I to VI) each containing 6 mice. Animals of groups I and II were administered 87.1 mg/kg b.w.(body weight) and 43.5 mg/kg b.w. respectively of thiamethoxam. Group III animals, lead acetate was administered orally and IV and V mice were administered combination of lead acetate and thiamethoxam at higher and lower dose level for 28 days. The group VI was control group. On 29^th day and humoral and cell mediated immune responses, TLC (Total leukocyte count), DLC (Differential leukocyte count), serum total protein, globulin and albumin, and histopathological studies were conducted.

Result:

The result obtained clearly indicated that on oral administration of thiamethoxam immunotoxicity was induced in mice in dose related manner. Lead acetate when administered for 28 days showed immunotoxic potential. Thiamethoxam and lead acetate when administered together did not lead to any new altered immunotoxic response but additive toxic effects of both were observed.

The determination of in vivo envelope-specific cell-mediated immune responses in equine infectious anemia virus-infected ponies

Distinct from human lentivirus infection, equine infectious anemia virus (EIAV)-infected horses will eventually enter an inapparent carrier state in which virus replication is apparently controlled by adaptive immune responses. Although recrudescence of disease can occur after immune suppression, the actual immune correlate associated with protection has yet to be determined. Therefore, EIAV provides a model for investigating immune-mediated protective mechanisms against lentivirus infection. Here, we have developed a method to monitor EIAV-envelope specific cellular immunity in vivo. An EIA carrier horse with no clinical signs infected 7 years ago and 4 related experimental ponies infected 6 months previously were used in this study. Forty-four 20-mer peptides, representing the entire surface unit protein (gp90) of EIAV, were combined into 14 peptide pools and intradermally injected into the neck of EIAV-infected horses. An identical volume of saline alone was injected into a fifteenth site as a negative control. After 48 h, those sites with palpable infiltrations were measured prior to the collection of 2mm and 4mm punch biopsies. Total RNA was extracted from each 2mm biopsy for determination of CD3 and interferon-γ (IFN-γ) mRNA expression by real-time PCR. The 4mm skin biopsies were formalin-fixed and paraffin-embedded for immunohistochemistry (IHC) staining for CD3, CD20, CD25 and MAC387 (macrophage marker). Peripheral blood mononuclear cells (PBMC) were obtained prior to the injection and tested for in vitro reactivity against the same peptides. Histological examination showed that some of the envelope peptides elicited a lymphocytic cellular infiltration at the injection site, as evidenced by positive staining for CD3. Gp90 peptide-specific increases in CD3 and IFN-γ gene expression were also detected in the injection sites. Furthermore, differences were found between in vivo and in vitro responses to gp90 specific peptides. These results demonstrate a novel method for detecting in vivo cell-mediated immune responses to EIAV-specific peptides that is readily applicable to other host/pathogen systems.

Relationship between systemic inflammation and delayed-type hypersensitivity response to Candida antigen in older adults

Research has shown that aging is associated with increased systemic inflammation as well as a reduction in the strength of immune responses. However, little evidence exists linking the decrease in cell-mediated immunity in older adults with other health parameters. We sought to examine the relationship between cell-mediated immunity as measured in vivo by the delayed-type hypersensitivity (DTH) response to candida antigen and demographic and physiological variables in older (65–80 y.o.) adults. Candida antigen response was not related to gender or obesity, or to a number of other physiological variables including fitness and body composition. However, positive responders had significantly lower serum C-reactive protein levels (CRP, p<0.05) vs. non-responders. Furthermore, subjects with CRP<4.75 mg•L⁻¹ had greater odds of developing a positive response compared to those with CRP>4.75 mg•L⁻¹. Therefore, positive responses to candida antigen in older adults appears to be related to lower levels of systemic inflammation.

Beyond the classical: influenza virus and the elucidation of alternative MHC class II-restricted antigen processing pathways

CD4+ T cells (T(CD4+)) are activated by peptides, generally 13-17 amino acids in length, presented at the cell surface in combination with highly polymorphic MHC class II molecules. According to the classical model, these peptides are generated by endosomal digestion of internalized antigen and loaded onto MHC class II molecules in the late endosome. Historically, this "exogenous" pathway has been defined through the extensive use of purified proteins. However, the relatively recent use of clinically relevant antigens, those of influenza virus in our case, has revealed several additional pathways of peptide production, including some that are truly "endogenous", entailing synthesis of the protein within the infected cell. Indeed, some peptides appear to be created only via endogenous processing. The cell biology that underlies these alternative pathways remains poorly understood as do their relative contributions to defence against infectious agents and cancer, and the triggering of autoimmune diseases.

Immunomodulation property of hexane fraction of leaves of Cinnamomum tamala Linn. in rats

The leaves of Cinnamomum tamala Linn. (CT) (Lauraceae) clinically used in Ayurveda as antidiabetic and diuretic, but no reports are available towards immunomodulating property. Its hexane fraction (CTH) was orally given to rats for 10 days and delayed type of hypersensitivity (DTH), antibody production against sheep red blood cells (SRBCs), mitotic index in bone marrow cells and concanavalin A (Con A) mediated proliferation of lymphocytes were assessed. Further on 30 days treatment, change in body weight (BW), spleen weight, thymus weight, bone marrow cellularity and hematological changes were observed. It inhibited significantly the DTH response (IC(50) 1475 +/- 57.19 mg kg(-1) BW), antibody production, suppressed mitotic index in bone marrow cells along with the suppression of lymphocyte proliferation against Con A (IC(50) 63.33 +/- 1.95 microg mL(-1)). In all experiments, cyclophasphamide and dexamethasone had been used as reference drug for in vivo and in vitro studies, respectively. On 30 days treatment, the CTH (800 mg kg(-1) BW and above) significantly suppressed growth rate, increase of spleen and thymus weight and low bone marrow cellularity. In hematological examination, it inhibited total white blood cell and lymphocytes count and increased per cent of polymorphs. Thus, it could be suggested that the fraction possesses immunosuppressive property at doses, higher than 800 mg kg(-1) BW in rats.

[Adjuvant disease in rats experimentally infected with Trypanosoma cruzi]

Se estudió la evolución de la artritis por adyuvante en ratas que habían sido infectadas previamente con Trypanosoma cruzi, con el objeto de evaluar su competencia inmunológica a través de la respuesta artrítica. La artritis por adyuvante se indujo en ratas adultas, endocriadas de ambos sexos, con 0.1 mi de adyuvante completo de Freund en la almohadilla plantar, en 2 lotes: a) inyectadas 90 días antes con 1 x 10(6) T. cruzi y b) testigos normales simultáneos. Se midieron, la lesión artrítica macroscópicamente con una escala semicuantitativa, y con microscopía óptica la histopatología de la lesión local y la del corazón, a los 180 días post-infecoión. La magnitud de las lesiones artríticas en las ratas con T. cruzi fue significativamente menor (p < 0.001) que la de los testigos, en todo el período. El infiltrado inflamatorio local, formado por linfocitos, plasmocitos y macrófagos fue significativamente menor (p < 0.001) en las ratas chagásicas, con respecto al de los testigos. Se postula que en las ratas que recibieron T. cruzi la respuesta artrítica menor podría deberse a una competición antigénica con los determinantes del parásito o a mecanismos inmunosupresores que interfieren en la producción de la entidad experimental.

Cardiopulmonary bypass and host defense functions in human beings: II. Lymphocyte function

In 47 patients undergoing open-heart surgical procedures, the influence of cardiopulmonary bypass (CPB) on lymphocyte function was investigated by studying in vitro the mitogen responses of lymphocytes in whole blood cultures. Subnormal mitogen responses before operation that likely resulted from dexamethasone medication were found in half of the patients studied. During operation, changes in phytohemagglutinin responses were uniform in a group of 23 patients. No significant effect of anesthesia and operation was observed until the patients were heparinized (i.e., before CPB). At the end of operation, the phytohemagglutinin response was below normal. In a group of 24 other patients, postoperative mitogen responses were studied. A tendency toward restoration of mitogen responses was observed in most patients the first morning after operation. However, no uniform pattern of normalization of mitogen responses was found. In an attempt to relate postoperative mitogen responses to trauma resulting from CPB, we observed that perioperative (in comparison with postoperative) administration of blood coincided with a significantly higher incidence of subnormal phytohemagglutinin and pokeweed mitogen responses on postoperative day 1. No correlation between laboratory data and clinical findings could be established.

Light and electron microscopic pulmonary lesions associated with retained microfilariae in canine occult dirofilariasis

Lungs from dogs infected with adult, gravid Dirofilaria immitis but without microfilaria circulating in systemic vessels were studied by light and transmission electron microscopy. Microfilariae were seen within the pulmonary microvasculature and in interstitial areas of interalveolar septa. An acute inflammatory reaction characterized by aggregates of eosinophils, neutrophils, macrophages and lymphocytes was associated with intact microfilariae. Necrotic and fragmented microfilariae were surrounded by macrophages and epithelioid cells. Other lesions in interalveolar septa of dogs with chronic occult dirofilariasis included endothelial degeneration and hypertrophy, perivascular aggregates of plasma cells, hypertrophy and hyperplasia of smooth muscle cells, and interstitial fibrosis. The findings suggest that a cell-mediated hypersensitivity reaction is at least partially responsible for retention of microfilariae in pulmonary parenchyma of dogs with occult dirofilariasis.

Attachment of cell fragments of Fusobacterium nucleatum to oral epithelial cells, gingival fibroblasts and white blood cells

The characteristic haemagglutination (HA) caused by Fusobacterium nucleatum strains was used for measuring their attachment to oral epithelial, gingival fibroblast and white blood cells. Whole cells and sonicated preparations of oral F. nucleatum strains VPI No. 4355, 10197 and ATCC No. 10953 haemagglutinated human and sheep red blood cells. Sonicated preparations of the organisms were tested for HA activity before and after absorption with human cells. Buccal epithelial, gingival fibroblast and white blood cells bound the HA-active fragments, as observed by: (1) decrease in the HA activity of the sonicated preparation after absorption, (2) increase in HA activity of the cells used for absorption, (3) presence of microbial fragments on the cells after absorption detected by fluorescent antibody. The HA-active fragments were released from the cells by EDTA; furthermore, galactose but not glucose inhibited the attachment of F. nucleatum to human cells. The role of cell binding in colonization by the organisms and in immune-stimulated damage to host cells is important.

Whipple's disease: a review emphasizing immunology and microbiology

Whipple's disease is an important and fascinating problem of local immunity in the gastrointestinal tract. Does the disease occur when an organism that is rare in nature infects an individual or do patients with Whipple's disease have a definable defect in their immune response that permits infection by a more common agent? Data in recent years indicate that there is only one type of microorganism that causes Whipple's disease. It is rod-shaped by electron microscopy and has a definable antigenic pattern by immunofluorescence. Paradoxically (considering its geometry), it reacts most strongly with antisera directed to streptococcal antigens. Patients with Whipple's disease do not have a disorder of immunoglobulin synthesis and do not have immune complexes present in their gut walls. Further, although earlier studies indicated that a defective response of T-lymphocytes to PHA is consistently present in these patients even years after therapy, more recent studies have found no consistent defect in mitogenic responses to PHA, CON A, or PWM. Also, recent studies indicate that mononuclear cells from patients with Whipple's disease usually mediate antibody-dependent cell-mediated cytotoxicity as well as controls, although spontaneous cell-mediated killing may be decreased. All these studies suggest that the defect is not primarily of lymphocytes, rather it is more likely that a defect exists in monocytes and macrophages. Future studies on Whipple's disease should add to existing knowledge of how the immune processes intracellular microorganisms.

A lymphokine-like factor isolated by deoxycholate from the membrane of human lymphocytes

1. Membranous protein fractions containing carbohydrates were solubilized from human tonsillar lymphocytes in the presence or basence of deoxycholate. The optimal conditions for the detergent treatment, high solubilized protein yield without cell disruption, temperature and time of the treatment and concentration of the detergent were elucidated. 2. The protein fractions inhibited both the mitogen-activated and the nonactivated DNA synthesis in human lymphocyte targets in vitro but did not affect the uptake of [3H]thymidine. The fractions had a slight effect on the amino acid incorporation into proteins and failed to influence the uptake of amino acids. 3. It is assumed that the investigated membranous proteins are lymphokine-like materials produced continuously by lymphocytes in vivo and are incorporated into the membrane of the cells.

Studies of orthotopic allografts of oral mucosa and skin across a histocompatibility barrier in a model system

The mucosal allograft offers a reproducibile model for the characterization of the response of the oral mucosa to immunopathologic processes. Orthotopic allografts of oral mucosa or of skin were exchanged between pairs of unrelated rabbits known to be either matched or mismatched at the major histocompatibility locus (RLA). Rabbits with autografts of these tissues served as controls. The behavior of allografts of oral mucosa and of skin, although similar in many ways, showed marked differences in the morphology of the rejection reaction including more striking vascular damage and vascular occlusion in skin and in the longer persistence of granulocytes throughout the period of rejection in mucosal allografts. The rejection of matched allografts appeared morphologically similar to that of mismatched grafts but the time sequence was delayed. Morphological differences between the rejection reactions in allografts or oral mucosa and those of skin may result from differences in the expression of histocompatibility and tissue specific antigens in these tissues as well as other local factors such as the nature and distribution of mucosubstances of the connective tissue ground substance, the regional blood flow, and the absorption of salivary components including water in an oral wound.

Pathogenesis and host response in subcutaneous alveolar hydatidosis. II. Intense plasmacellular infiltration in the paracortex of draining lymph nodes

Male C57L/J mice were infected subcutaneously in the left flank with 10 cysts of Echinococcus multilocularis. The draining and contralateral nodes were excised at weekly intervals, weighed, and examined histologically. Lymphoproliferation occurred in both the follicles and the paracortex (PCA) of the draining lymph nodes at one week postinfection (p.i.). Disorganization in the PCA of the draining nodes, was characterized by replacement of lymphocytes by plasma cells and the flattening of the endothelial cells lining the postcapillary venules. This began at three weeks p.i. and was completed by 12 weeks p.i. No comparable alterations occurred in the contralateral nodes during this period, but at 22 weeks p.i. these nodes were disorganized and histologically identical to the draining nodes. The growth and histogenesis of the subcutaneous alveolar cysts correlated with the expansion and disorganization of the PCA. The regulation of subcutaneous murine alveolar hydatidosis is discussed with reference to immune-deviation which is brought about by the antigenic load and plasmacellular infiltration in the draining lymph nodes.