Submitted to: American Association of Immunologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/4/1999
Publication Date: N/A
Technical Abstract: The role of intestinal lymphocytes and IFN production in protective immunity to Eimeria tenella infection was evaluated in two inbred strains of chickens (SC and TK) that display different patterns of susceptibility to coccidiosis. Oral inoculation of either strain with E. tenella lead to parasite invasion of the intestinal cecum and cecal tonsils. Greater fecal oocyst shedding was seen in TK chickens. Flow cytometric analyses of ceca tonsil lymphocytes demonstrated greater numbers of CD4+ and TCR1+ cells in SC chickens and elevated numbers of CD8+ and TCR2+ cells in TK chickens following primary infection. IFN-gamma mRNA expression was significantly increased in cecal tonsil and intraepithelial lymphocytes at days 6 and 8 post-primary infection respectively in SC compared to TK chickens. While no differences were noted between cecal tonsil lymphocytes of the two strains following secondary infection, TK chickens showed elevated IFN-gamma transcript levels in intestinal intraepithelian lymphocytes at this time. Selective depletion of CD4+, but not CD8+, cecal tonsil lymphocytes in SC chickens resulted in a reduced IFN-gamma mRNA expression indicating that CD4+ cells are the primary source of this cytokine. Collectively, these results indicate that local lymphocyte responses and production of IFN-gamma are influenced by host genetic factors.