Immune responses in bovine tuberculosis.

Knowledge of the immune responses which develop in cattle following infection with Mycobacterium bovis is essential both to the understanding of disease pathogenesis and to the logical development of immune-dependent tools, such as diagnostic tests and vaccines, which can be used to combat the disease. Studies of field cases of bovine tuberculosis (TB) and of experimental bovine models of M. bovis infection have indicated that cell-mediated immune responses (CMI) predominate within a spectrum of immunity which exists. This paper reviews aspects of recent research and indicates how knowledge of T-cell antigenic targets in bovine TB along with increasing knowledge of T-cell subpopulations and their interactions with M. bovis -infected macrophages provides opportunities for the development of better methods for disease control.     

Immune responses of diabetic animals

The blastogenic responses of lymphocytes from chemically-induced (streptozotocin) and genetically-diabetic C57B1/6J (ob/ob) obese mice were assessed using mixed-lymphocyte cultures (MLC) and mitogens selective for thymus-derived (T cell) and bone marrow-derived (B cell) lymphocytes. Splenic lymphocytes from obese and normal C57B1/6 mice exhibited similar responses to the nonspecific T and B cell mitogens, Concanavalin A (Con A) and E. coli lipopolysaccharide (LPS), respectively. A small (25%) depression of the blastogenic response in MLC was observed for lymphocytes from obese mice. The generation of cytotoxic T cells in vitro in response to trinitrobenzene sulphonic acid (TNP)-modified syngeneic spleen cells was the same for normal and obese mice. In contrast, splenic lymphocytes from 7-14 day streptozotocin-diabetic mice had lower (56-60%) proliferative responses in MLC. The generation of cytotoxic effector cells in vitro was lower for spleen cells for spleen cells from 22-day streptozotocin mice, although blastogenic responses in MLC were not depressed. The insulin-deficient streptozotocin mice appear to have a depression of some thymus-derived cell functions that may be associated with streptozotocin rather than the diabetic state. Direct immunosuppressive effects of streptozotocin are indicated by the marked decrease in the number of lymphocytes in the thymus, lymph nodes, and spleen.     

Immune responses to varicella-zoster in the aged

Skin test reactivity and in vitro lymphocyte stimulation responses to varicella-zoster (VZ) were examined in a large normal population ranging in age from 6 months to 93 years. Warning of cellular immunity, as examined by skin delayed hypersensitivity, began at age 40 years. Skin test responses to phytohemagglutinin, however, remained positive into the eighth decade of life. In vitro lymphocyte stimulation responses to VZ were usually positive (stimulation index greater than or equal to 2.5) until age 60 years, after which time levels, as observed with nonimmune individuals, were often demonstrated. Antibody levels, as measured by fluorescent antibody to membrane antigen, remained positive into the ninth and tenth decades of life. This was especially so with a history of reactivation (zoster) VZ infections, while skin test and in vitro responses were rarely positive in those individuals. This cellular, as contrasted with humoral, immunity decreases with advancing age, which may account for a propensity to reactivation of VZ virus.     

血吸虫病免疫应答及其调节

该文以血吸虫生活史不同发育阶段(尾蚴、虫卵、成虫)诱导的免疫应答以及血吸虫病临床各期(急性期和慢性期)的免疫应答为主,综述近年来血吸虫病免疫应答的研究进展.在血吸虫病免疫应答的调节方面内容较多,限于篇幅,该文主要从细胞因子的调节作用,参与免疫应答调节的淋巴细胞及其亚类(或表型),尾蚴(或童虫)排泄分泌抗原(0-3hRP等)中某些具免疫调节作用的分子等3方面加以综述.     

Immune responses in hepatitis B virus infection

Hepatitis B virus infection is one of the most frequent causes of chronic liver disease worldwide. Even though a preventive vaccine is available, the search for a cure for chronically infected patients remains a high priority to reduce the morbidity and mortality from liver cirrhosis and hepatocellular carcinoma. This review summarizes the immune response in acute, self-limited and chronic hepatitis B; its differential effects on viral replication and liver injury; and prospects for immunotherapy.     

Immune responses to Chlamydia antigens in atherosclerosis

Aim of this study was to isolate T lymphocytes from atheromatous plaques and to determine they respond to Chlamydia antigens. Atheromatous plaques from carotid endarterectomy patients, were cultured in vitro with the T cell growth factor, IL-2. This rarely allowed outgrowth of T cell lines. However, when combined with a mitogenic or antigenic stimulus to T cells, T cell lines were obtained from most patients, and from approximately 30% of replicate plaque tissue fragments. Chlamydia organisms were as effective in allowing the establishment of T cell lines as other recall antigens. T cell lines were tested for their ability to recognize antigens presented by autologous macrophages. Some lines responded to Chlamydia organisms, and also to the recombinant Chlamydia proteins hsp60 and OMP2. However, other lines recognized recall antigens. These results indicate that the atheromatous plaque contains memory T lymphocytes, and amongst the antigens they recognize are Chlamydia proteins. Stimulation of T cells was required to allow outgrowth in vitro, suggesting that the T cells were not in an activated state in vivo. However, since Chlamydia pneumoniae is present in the atheromatous plaque, activation of Chlamydia-reactive T cells by local antigen is a potential pro-inflammatory mechanism which could contribute to the pathogenesis of atherosclerosis.     

Immune responses to Helicobacter pylori infection

Helicobacter pylori(H.pylori)infection is one of the most common infections in human beings worldwide.H.pylori express lipopolysaccharides and flagellin that do not activate efficiently Toll-like receptors and express dedicated effectors,such asγ-glutamyl transpeptidase,vacuolating cytotoxin(vacA),arginase,that actively induce tolerogenic signals.In this perspective,H.pylori can be considered as a commensal bacteria belonging to the stomach microbiota.However,when present in the stomach,H.pylori reduce the overall diversity of the gastric microbiota and promote gastric inflammation by inducing Nod1-dependent pro-inflammatory program and by activating neutrophils through the production of a neutrophil activating protein.The maintenance of a chronic inflammation in the gastric mucosa and the direct action of virulence factors(vacA and cytotoxinassociated gene A)confer pro-carcinogenic activities to H.pylori.Hence,H.pylori cannot be considered as symbiotic bacteria but rather as part of the pathobiont.The development of a H.pylori vaccine will bring health benefits for individuals infected with antibiotic resistant H.pylori strains and population of underdeveloped countries.     

Immune responses in the lung: Basic principles

The basic elements which regulate immunomodulation at the lung level and the constituents of in situ pulmonary host defense mechanisms that recognize, destroy, and remove potentially harmful inhaled antigenic materials are discussed. The relevance of these processes in term of pathogenesis of some lung disorders is briefly exemplified.