CD4-CD8- T cells in CD4-Deficient Mice Provide Help for Mucosal IgA to Salmonella

概要

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Our previous studies have shown that antigen-specific mucosal immune responses are induced in CD4 gene disrupted (CD4-/-) mice after oral immunization with recombinant Salmonella expressing fragment C of tetanus toxin (rSalmonella-Tox C). Furthermore, significant delayed-type hyper responsivities were detected. These findings indicate that antigen-specific T cells are induced in the absence of CD4 molecule. In this study, we further elucidated nature of antigen-specific T cells in those immunized mice. Analysis of T cell proliferative responses showed that a significant tetanus toxoid-specific proliferation was induced in CD4-CD8-, but not CD4-CD8+, T cells from Peyers patches and spleen of CD4-/- mice given rSalmonella-Tox C orally. Furthermore, these CD4-CD8- T cells produced Th1 (IFN-γ and IL-2) and Th2 (IL-4) cytokines after oral immunization with rSalmonella-Tox C. Finally, CD4-CD8- T cells isolated from Peyers patches of immunized CD4-/- mice when added to B cell cultures induced increased number of tetanus toxoid-specific IgG and IgA producing cells. These results suggest that CD4-CD8- T cells in CD4-/- mice are capable of inducing antigen-specific T helper cytokines and provide help for mucosal and systemic antibody responses against orally administered rSalmonella in the absence of CD4+ T cells.