Submitted to: Journal of the American Veterinary Medical Association
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2000
Publication Date: N/A
Technical Abstract: Objective: The role of intestinal lymphocytes and IFN-gamma production in protective immunity to E. tenella infection was evaluated in two inbred strains of chickens (SC and TK) that display different patterns of disease susceptibility to coccidiosis. Procedure: Disease susceptibility of SC and TK chickens was tested by infection with E. tenella and their local IFN-gamma mRNA production and cellular changes were evaluated. Results: E. tenella infection led to parasite invasion of not only cecum but also cecal tonsils with greater fecal oocyst shedding in TK chickens. Greater numbers of CD4+ and TCR alpha-beta cells in SC chickens and elevated numbers of CD8+ and TCR gamma-beta +cells in TK chickens following primary infection were observed. IFN-gamma mRNA expression was significantly increased in cecal tonsil and intraepithelial lymphocytes post-primary infection in SC. Selective depletion of CD4+ but not CD8+ cecal tonsil lymphocytes in SC chickens resulted in a reduction in IFN-gamma mRNA expression indicating that CD4+ cells are the primary source of production of this cytokine. Conclusion: Collectively, these results indicate that the production of IFN-gamma and local lymphocyte responses are under host genetic factor(s) which influence the magnitude of the host innate immunity to E. tenella. (This work was supported by the CSRS, USDA, NRI grant under agreement 98-35204-6471).