Immune defence mechanism against blood-borne Pasteurella multocida in turkeys

Humoral and cellular immune defence factors involved in controlling blood-borne Pasteurella multocida were investigated in turkeys by the passive transfer of immune serum or by the treatment with macrophage-activating agents. The treated and untreated birds were intravenously inoculated with a virulent strain of P multocida, and the viable bacteria in the blood, liver and spleen were counted. In untreated birds, the bacteria were rapidly removed from the blood, and the majority were recovered from the liver and spleen 120 minutes after inoculation. Neither the transfer of immune serum nor the treatment with macrophage-activating agents significantly influenced the clearance rate of bacteria from the blood. The number of bacteria recovered from the liver 120 minutes after inoculation was slightly lower in the birds treated with macrophage-activating agents and significantly lower in those given immune serum than in the untreated birds. None of the treatments, however, significantly changed the number of bacteria recovered from the spleen 120 minutes after inoculation. The results suggest that the phagocytes in the liver, but not in the spleen, play a crucial role in the intravascular defence against P multocida in the presence of specific antibodies.     

Immune mechanisms in Marek's disease.

Resistance to progressive tumor development in MD is either naturally inherited or can be induced by vaccination with apathogenic or attenuated MDV or with HVT. Studies on the effects of immunosuppression on resistance have shown that natural and vaccine induced resistance may be mediated through immune responses. Cell-mediated immune responses rather than humoral responses appear to be of principal importance. The antigen(s) against which protective cell-mediated immunity is elicited are not yet clearly delineated. Both virus-related and tumor antigens may be involved. Progress in the understanding of cell-mediated immunity in MD has been slow because of lack of reproducible in vitro tests to measure this response in infected chickens. The development of lymphoblastoid cell lines from MD lymphomas, however, has enabled the development of an in vitro cytotoxicity test. In this test, which utilizes MSB-1 cells as the target cells, a specific cell-mediated immune response, presumably against the tumor antigen, MATSA, was detected in chickens infected with MDV. Further studies using similar in vitro tests will facilitate a better understanding of the role cell-mediated immune responses might play in development of MD.     

Immune mechanisms in infections of poultry

Resistance to infectious agents may depend upon innate mechanisms or acquired immune responses. Inflammation, phagocytosis, cell-mediated immunity and antibodies are components of a complex reaction which result either in resistance or in susceptibility. Most infectious organisms stimulate immune responses within every compartment of the immune system. In rather few infections of poultry, it is possible to pinpoint a limited number of immune reactions that are primarily responsible for resistance. In some situations, autoimmunity may contribute to the pathology associated with infections.     

结核分枝杆菌感染与巨噬细胞凋亡的免疫机制研究进展

结核分枝杆菌感染后,巨噬细胞凋亡被认为是抵抗其进一步入侵的重要机制之一,巨噬细胞发生凋亡后可以杀死胞内的结核分枝杆菌,进一步地加工、递呈抗原,激活邻近尚未感染的巨噬细胞,增强机体的免疫应答能力。结核分枝杆菌也会通过一系列机制来抑制巨噬细胞的凋亡,以逃避巨噬细胞的杀伤。结核分枝杆菌对宿主巨噬细胞凋亡的调控呈现出复杂性和多面性,进一步研究其具体调控机制有助于人们更好地预防和控制结核病。     

Immune mechanisms of the bovine udder: an overview

Understanding basic defenses of the udder is instrumental in developing measures to prevent mastitis. The teat canal is the first defense against pathogens, providing a physical barrier and antimicrobial substances. When bacteria breach the teat canal, milk leukocytes provide a second defense by ingesting pathogens. Intramammary devices have been used experimentally to increase leukocyte numbers and to enhance destruction of bacteria. Milk antibodies opsonize and lyse bacteria, neutralize toxins, and prevent adhesion to tissue. Vaccinating cows against mastitis generally has been unsuccessful; however, immunization is useful in controlling specific bacterial strains. Antibody-producing plasma cells preferentially accumulate in internal teat end tissues. Because bacteria contact these tissues to reach milk-producing areas of the udder, an immunostimulant to enhance locally the protective nature of plasma cells may decrease the occurrence of infection.     

Cellular and humoral defence mechanisms in mares susceptible and resistant to persistent endometritis

Both random and directional migration of blood neutrophils from 9 mares susceptible to persistent endometritis were significantly less (p less than 0.05) than neutrophils from 8 resistant mares. Serum from susceptible mares had significantly more (p less than 0.01) chemotactic activity than serum from resistant mares. Although phagocytosis of yeast blastospores by blood neutrophils from 4 resistant and 3 susceptible mares was similar, uterine neutrophils from susceptible mares were significantly worse (p less than 0.01) at phagocytosis than uterine neutrophils from resistant mares. Uterine washings from 17 susceptible mares were significantly better at opsonising yeast blastospores than washings from 14 resistant mares; however, washings from both groups had a similar ability to promote killing of S. zooepidemicus by neutrophils. When an immunologically non-specific endometritis was induced, washings from 3 susceptible mares were significantly worse at promoting bactericidal activity by 144 h than washings from 4 resistant mares (p less than 0.01). Haemolytic complement activity was significantly greater (p less than 0.001) in washings from 17 susceptible mares than from 14 resistant mares. Induction of acute endometritis resulted in high levels of haemolytic complement activity in 2 of 3 susceptible mares at 24 and 144 h, but only in small increases in 4 resistant mares. Thus, some abnormalities in neutrophil function were detected and a possible defect in promotion of neutrophil bactericidal activity by uterine secretions from susceptible mares but there was no evidence for any deficiency in haemolytic complement activity.     

Variations in host defence mechanisms and blastogenesis in chickens and mice after rifamycin treatments

The immunobiological effect of rifamycins on different experimental models has been comparatively studied in chickens and mice using cyclophosphamide as a reference immunosuppressive agent. "In vivo" treatments with rifampicin and rifamycin SV diminished interferon levels in chickens and mice up to two hours after virus challenge. Mitogen induced blastogenesis was significantly depressed by either "in vivo" (5-50 mg/kg) or "in vitro" (5-20 micrograms/ml) drug treatments, although the activation of B lymphocytes was more easily inhibited than that of T lymphocytes. Primary anti-SRBC immune responses suffered a similar immune suppressive action by rifamycin treatments "in vivo". In every case, cyclophosphamide (10-20 micrograms/ml "in vitro" and 25 mg/kg "in vivo") proved to be the most active immunosuppressant. On the other hand, a remarkable parallelism in the effect of rifamycins in chickens and mice was observed in all the experimental systems used.     

鸡新城疫纳米蜂胶灭活疫苗免疫作用机理

采取单因素随机分组的试验设计,研究了以蜂胶纳米蜂胶颗粒作为佐剂的新城疫灭活疫苗对鸡的免疫保护效果,测定了免疫器官指数的影响、体液免疫的变化、以及对腹腔巨噬细胞活性的影响。疫苗免疫后7d攻毒,免疫保护率为70.0%。在注射后7d,胸腺指数:A组与B组和C组相比各周均无显著性差异(P0.05),但可看出A组有提高的趋势,D组其胸腺指数也高于E组,注射后21d时差异显著(P0.05)。免疫后每周所测抗体结果均为A组最高,B组次之,C组最差。A组产生抗体早,B组与之相比产生抗体的高峰期晚。该疫苗能促进鸡免疫器官的生长、发育和成熟,促进免疫细胞的分化和增殖,使血液循环中T淋巴细胞增多,使腹腔巨噬细胞活性增强。蜂胶苗产生抗体早,可以获得早期保护。     

Immune mechanisms in the pathogenesis of viral diseases: a review.

Three immunopathological mechanisms may determine the pathogenesis of viral diseases in animals. (1) A variety of viruses causes transient or prolonged immunosuppression by infecting lymphoreticular tissues and interacting with components of the immune system. (2) In persistent viral infections effective immune responses may result in tissue damage. The mechanisms involved are T-cell-mediated destruction of infected cells and delayed-type hypersensitivity. (3) In a number of viral diseases pathogenic immune complexes are formed when antibodies are produced and react with viral antigen molecules persisting in the host. The selected examples of immune dysfunction are the focus of this review.     

β-葡聚糖可增强猪的自身免疫力

最新的研究表明,如果猪饲料富含酵母细胞壁中提取物β-葡聚糖,那么猪的免疫系统可被大大地激活,促使猪和仔猪在应对感染或致病威胁时能够作出快速、有效的免疫应答反应。它意味着猪获得了一个更好健康保护。