Mechanism And Effect On Changes Of Interleukin-2 Activity And Immune Function Of Chicks Infected With E.necatrix

Fourteen-days-old AV2000 broiler chicks were used in the experiment. The peripheral blood, thymus, bursa of Fabricus and spleen were sterilely removed for the culture of their lymphocytes. The T-lymphocytes proliferative responses to concanavalin A(ConA)were determined by MTT assay, and culture supernatants of lymphocytes stimulated with ConA were assayed for the inductive activity of interleukine-2(IL-2). The B-cells were stimulated with phorble myristate acetate(PMA)to determine the B-lymphocyte proliferative responses in vitro. The dynamic changes of these objects above were observed in the study, in order to disclose comprehensively regular rule of changes of peripheral blood and immune organs function and of immune regulation of cytokins post primary infection and reinfection with E.necatrix, and accordingly provide rational founderation for immunotherapeutic approaches to this disease control strategies. The results were as follows:IL-2 inductive activity of T-lymphocytes from thymus and spleen was significantly increased (p<0.05 or p<0.01) compared with that of controls, respectively, from 16 to 18 and 18 to 21 days post primary infection. T-lymphocytes proliferative response to ConA in vitro of peripheral blood, thymus and spleen was enhanced from 16 to 24, 14 to 16 and 10 to 18 days post primary infection, respectively. B-lymphocytes proliferative response to PMA in vitro of peripheral blood, spleen and bursa of Fabricus was higher than that of controls from 16 to 21, 14 to 24 and 14 to 21 days post primary infection, respectively. The results showed that IL-2 production was augmented, namely, molecular immune function of cytokines of central and peripheral immune organs was up regulated; and cellular and humoral immunity was elicited.IL-2 inductive activity of T-lymphocytes of thymus was significantly lower than that of primary infection chicks and control chicks from 4 to 7 days post secondary challenge infection. IL-2 inductive activity of T-lymphocytes of spleen was also some extent low compared with that of primary infection chicks and controls from 2 to 10 days post secondary challenge infection. These observations disclosed that IL-2 inductive activity of T-lymphocytes of thymus and spleen remarkably descended post challenge infection, and further suggested that molecular immune regulation of cytokines was inhibited. Cellular immunity and humoral immunity were, also temporarily, depressed at forepart of secondary infection.Immune function of chicks secondarily infected with E.necatrix began to refresh 7 days post secondary infection. IL-2 inductive activity of T-lymphocytes of thymus and spleen was remarkably higher than, with a trend to continued enhancement, that of primary infection chicks and controls 14 days post secondary infection, and the same to T or B cells proliferative function of thymus, spleen and bursa of Fabricus. The results above indicated that higher level immunity against E.necatrix was produced after primary infection, thereby successfully resisted secondary infection with a dose of 100 000 sporulated oocysts one chick. Immune function refeshed at anaphaes of secondary infection with E.necatrix, which showed anamnestic response to reinfection with E.necatrix was elicited.In brief, some extent level of cellular immunity and humoral immunity against E.necatrix was elicited after primary infection, thereby resisted definited dose of oocytes of E.necatrix reinfection, futher elicited anamnestic response to reinfection of E.necatrix.Candidate: Hu Jingyou Speciality: Basic Veterinary ScienceSupervisor: Zheng Shimin...