T lymphocytes may play a regulatory role in the development of allergic airway hyperresponsiveness (AHR). We have studied the relationship between airway responsiveness and a number of immunological changes in Brown-Norway rats sensitized intraperitoneally and repeatedly exposed to ovalbumin (OVA) aerosol. Acetylcholine provocation concentration (PC)150 (the concentration of acetylcholine causing a 150% increase of base-line lung resistance) was measured and peripheral blood and bronchoalveolar lavage (BAL) cells were collected 18-24hr after the final exposure. Total and OVA-specific IgE in serum was measured by enzyme-linked immunosorbent assay (ELISA). Mononuclear cells were analysed by flow cytometry after labelling with monoclonal antibodies against CD2 (pan T-cell marker), CD4, CD8 (T-cell subsets) or CD25 (interleukin-2 receptor). There were significant differences in PC150 (P
Cell-mediated immune mechanisms have long been suspected of playing an important role in the pathogenesis of various renal diseases. An animal model of active nephritis secondary to an exogenous antigen that requires antigen presentation to immune-competent T cells has not been developed. Consequently, the potential of kidney cells to serve as effective antigen presenting cells after an exposure to a therapeutic, biological, or environmental agent in the intact animal has not been documented. The present experiments were designed to demonstrate the capacity of the kidney to become the target for cell-mediated immune injury. A model system has been developed whereby a chemically reactive form of the hapten azobenzenearsonate is introduced directly into the left kidney of pre-immunized Brown Norway rats. Previous studies have shown that this form of the hapten requires active antigen presentation but no intracellular processing, since the reactive form of the hapten modifies directly surface expressed proteins. Delayed hypersensitivity was demonstrated in the actively immunized animals by standard lymphocyte stimulation index and by in vivo skin testing. Peak foot pad swelling of 220 +/- 13 x 10(-2) mm in response to the hapten was observed between days 11 and 14 as compared to
Development of Francisella tularensis antigen responses measured as T-lymphocyte proliferation and cytokine production (tumor necrosis factor alpha, gamma interferon, and interleukin-2 and -4) during human tularemia.
The lymphocyte immune reactivity of 12 tularemia patients to Francisella tularensis antigens prepared from the bacterial cell envelope was examined during a 14-week follow-up study. Lymphocyte blast transformation responses of peripheral blood mononuclear cells (PBMC) to different protein antigens appeared simultaneously 2 weeks after the first symptoms of tularemia, indicating that none of these antigens had any special role at the early phase of immunization. While the lymphocyte blast transformation responses of total lymphocytes to all bacterial antigens were negative in the week 1 samples, continuously growing F. tularensis-specific T-lymphocyte lines were obtained from PBMC at the same time, indicating that an immune response had already occurred. Later, the T-lymphocyte lines and lymphocyte blast transformation responses were similar. Lymphocyte activation among the PBMC was reflected in an increased number of HLA-DR antigen-expressing, CD4-positive T lymphocytes (CD4+ DR+). The mean secretion of soluble CD8 from F. tularemia antigen-stimulated PBMC increased 2 weeks after tularemia onset, but the mean number of CD8+ DR+ T lymphocytes did not vary during the study period and no correlation could be found between the soluble CD8 and number of CD8+ DR+ T lymphocytes. F. tularemia antigen-induced cytokine production was measured from the PBMC supernatants. High levels of tumor necrosis factor alpha were detected from the first week onwards. The highest levels of interleukin-2 and gamma interferon were recorded during the second and third weeks, respectively, after tularemia onset. Interleukin-4 could not be demonstrated in the lymphocyte supernatants.
The trend towards an increased consumption of minimally processed plant food results in a higher intake of non-nutritive compounds such as lectins. Lectins are typically globular proteins that are resistant to digestion in the gastrointestinal tract. They affect the integrity of the intestinal epithelium and the absorption of dietary antigens, and induce the release of allergic mediators from mast cells in vitro. Based on this information we have studied whether dietary wheat germ agglutinin (WGA) could be involved in triggering food allergies. Brown Norway rats were immunized intraperitoneally using ovalbumin (OVA; 10 microg/rat) and 10 d later treated for five consecutive days with WGA (10 mg/rat per d) administered intragastrically. Rats were then orally challenged with OVA (100 microg/rat) 1 h after the last WGA application, and blood was collected 4 h later. Immunological responses (anti-OVA immunoglobulins E and G, rat mast cell protease II, interferon-gamma and lymphocyte proliferation) were measured and lymphocyte subpopulations were determined. In immunized rats WGA treatment resulted in increased serum rat mast cell protease II concentrations (pre-challenge 0.26 (SE 0.08) microg/ml, post-challenge 0.49 (SE 0.09) microg/ml; P
The Francisella tularensis T-lymphocyte antigens, which may have a role in protection against tularemia, were investigated with vaccine-immunized subjects. Preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to fractionate the bacterial envelope preparation. The 23 fractions obtained represented membrane proteins of different apparent molecular masses ranging from 10 to 150 kilodaltons. Different fractions contained one to four separate protein bands stained with Coomassie blue. The lymphocyte blast transformation responses of five tularemia vaccine-immunized and three nonimmunized subjects were tested against bacterial material eluted out of SDS-PAGE fractions. Every fraction stimulated lymphocytes from at least one of the subjects. No clearly immunodominant or inhibitory antigens were detected among the envelope fractions. Expression of the HLA-DR antigen at the surface of CD4- and CD8-positive lymphocytes was also studied as a measure of cell activation. The numbers of CD4+ DR+ cells varied directly with the lymphocyte proliferation profiles, and very few CD8+ cells were found in the preparations stimulated with the different fractions. The diversity of the antigens recognized by immune T lymphocytes was confirmed by using F. tularensis-specific T-lymphocyte clones obtained from vaccinated subjects. Most of the 36 T-lymphocyte clones tested were stimulated by one SDS-PAGE fraction only.
Immunization with a tetanus-protein (TT) pneumococcal polysaccharide (PPS) conjugate vaccine (Pnc1-TT) induces protective immunity against lethal pneumococcal infections in neonatal and infant mice, but anti-PPS IgG response and protective efficacy is lower than in adult mice. Here, we show that reduced antibody (Ab) response and protection against infections is directly related to impaired T cell response to the carrier. Whereas spleen cells from adult mice immunized with Pnc1-TT responded with proliferation and IFN-gamma secretion to in vitro stimulation with TT, spleen cells from neonatal and infant mice did not. However, significant, but age dependent, Th2-cytokine responses were observed in mice immunized with Pnc1-TT. Impaired IFN-gamma production upon TT-stimulation in vitro was also reflected in reduced IFN-gamma/IL-5 ratio. The IL--5 response correlated with IgG anti-PPS titers, and the lack of PPS Ab in the majority of neonatal mice was clearly associated with absence of carrier-specific IL-5 production. These results show that immunization with Pnc1-TT induces carrier-specific T cell responses that increase with age and determine the levels of PPS-specific Ab elicited. Whereas a weak and Th2-biased response was observed in neonatal mice, infant mice showed a mixed Th1-Th2 response as observed in adults.
Endotoxin-dependent direct inhibition of functional activity of T-cell immunity and biological activity of thymus factors was revealed in patients with recurrent chronic bronchitis and with systemic endoxinemia. The findings are considered by authors as an important pathogenetic mechanism inhibiting stable regression of inflammation in bronchopulmonary system in juvenile patients with recurrent chronic bronchitis. The correction of systemic endoxinemia in such patients is pathophysiologicaly substantiated.
Exopolysaccharides from Cyanobacterium aponinum from the Blue Lagoon in Iceland increase IL-10 secretion by human dendritic cells and their ability to reduce the IL-17+ROR?t+/IL-10+FoxP3+ ratio in CD4+ T cells.
Regular bathing in the Blue Lagoon in Iceland has beneficial effects on psoriasis. Cyanobacterium aponinum is a dominating member of the Blue Lagoon's microbial ecosystem. The aim of the study was to determine whether exopolysaccharides (EPSs) secreted by C. aponinum (EPS-Ca) had immunomodulatory effects in vitro. Human monocyte-derived dendritic cells (DCs) were matured in the absence or presence of EPS-Ca and the effects were determined by measuring the secretion of cytokines by ELISA and the expression of surface molecules by flow cytometry. DCs matured with EPS-Ca at 100 µg/ml secreted higher levels of IL-10 than untreated DCs. Subsequently, DCs matured in the presence or absence of EPS-Ca were co-cultured with allogeneic CD4(+) T cells and their effects on T cell activation analysed by measuring expression of intracellular and surface molecules and cytokine secretion. Supernatant from allogeneic T cells co-cultured with EPS-Ca-exposed DCs had raised levels of IL-10 compared with control. A reduced frequency of IL-17(+)ROR?t(+) T cells was observed when co-cultured with EPS-Ca-exposed DCs and a tendency towards increased frequency of FoxP3(+)IL-10(+) T cells, resulting in a lower IL-17(+)ROR?t(+)/FoxP3(+)IL-10(+) ratio. The study shows that EPSs secreted by C. aponinum stimulate DCs to produce vast amounts of the immunosuppressive cytokine IL-10. These DCs induce differentiation of allogeneic CD4(+) T cells with an increased Treg but decreased Th17 phenotype. These data suggest that EPSs from C. aponinum may play a role in the beneficial clinical effect on psoriasis following bathing in the Blue Lagoon.
Experimental autoimmune myasthenia gravis (EAMG) is a T cell-dependent, Ab-mediated autoimmune disease induced in rats by a single immunization with acetylcholine receptor (AChR). Although polarized Th1 responses have been shown to be crucial for the development of mouse EAMG, the role of Th cell subsets in rat EAMG is not well established. In the present work we show that while the incidence and severity of EAMG are similar in Lewis (LEW) and Brown-Norway (BN) rats, strong differences are revealed in the immune response generated. Ag-specific lymph node cells from LEW rats produced higher amounts of IL-2 and IFN-gamma than BN lymph node cells, but expressed less IL-4 mRNA. IgG1 and IgG2b anti-AChR isotype predominated in BN and LEW rats, respectively, confirming the dichotomy of the immune response observed between the two strains. Furthermore, although IL-12 administration or IFN-gamma neutralization strongly influenced the Th1/Th2 balance in BN rats, it did not affect the disease outcome. These data demonstrate that a Th1-dominated immune response is not necessarily associated with disease severity in EAMG, not only in rats with disparate MHC haplotype but also in the same rat strain, and suggest that in a situation where complement-fixing Ab can be generated as a consequence of either Th1- or Th2-mediated T cell help, deviation of the immune response will not be an adequate strategy to prevent this Ab-mediated autoimmune disease.
BACKGROUND: A study was performed to compare the effects of immunization with ragweed pollen (RW) in two different adjuvants on the characteristics of a previously described model of experimental immune-mediated blepharoconjunctivitis (EC) in rats. METHODS: Lewis or Brown Norway (BN) rats were immunized with 100 microg of RW in emulsion with aluminum hydroxide [Al(OH)3] or complete Freund's adjuvant (CFA). Three weeks later, the animals were challenged with eye drops containing RW in PBS. Twenty-four hours after topical challenge, eyes, blood, and lymph nodes were obtained for histology, measurement of antigen-specific antibodies, and proliferation or cytokine assays, respectively. In addition to active immunization, recipients of RW-primed lymph node cells were challenged and evaluated as above. RESULTS: RW in both adjuvants induced infiltration with predominantly mononuclear cells in Lewis rats and eosinophils in BN rats. As well as active immunization, eosinophils were detected only in BN rats by adoptive transfer of cells. Lymphocyte proliferative responses to RW were high in immunized Lewis rats when CFA was used as an adjuvant. In contrast, proliferative responses in BN rats were higher when Al(OH)3 was used. RW-specific IgE was detected only in BN rats. There were no significant differences in RW-specific IgG1/IgG2a ratio among the four groups. Lewis rats had higher level of RW-specific interferon-gamma in the culture supernatant. CONCLUSIONS: The characteristics of EC are different in Lewis and BN rats, dependent on the genetic background of the rat strains. The response to RW was similar to other previously used antigens, such as ovalbumin.