CD4+ NKT Cells, But Not Conventional CD4+ T Cells, Are Required to Generate Efferent CD8+ T Regulatory Cells Following Antigen Inoculation in an Immune-Privileged Site

Following inoculation of Ag into the anterior chamber (a.c.), systemic tolerance develops that is mediated in part by Ag-specific efferent CD8(+) T regulatory (Tr) cells. This model of tolerance is called a.c.-associated immune deviation. The generation of the efferent CD8(+) Tr cell in a.c.-associated immune deviation is dependent on IL-10-producing, CD1d-restricted, invariant Valpha14(+) NKT (iNKT) cells. The iNKT cell subpopulations are either CD4(+) or CD4(-)CD8(-) double negative. This report identifies the subpopulation of iNKT cells that is important for induction of the efferent Tr cell. Because MHC class II(-/-) (class II(-/-)) mice generate efferent Tr cells following a.c. inoculation, we conclude that conventional CD4(+) T cells are not needed for the development of efferent CD8(+) T cells. Furthermore, Ab depletion of CD4(+) cells in both wild-type mice (remove both conventional and CD4(+) NKT cells) and class II(-/-) mice (remove CD4(+) NKT cells) abrogated the generation of Tr cells. We conclude that CD4(+) NKT cells, but not the class II molecule or conventional CD4(+) T cells, are required for generation of efferent CD8(+) Tr cells following Ag introduction into the eye. Understanding the mechanisms that lead to the generation of efferent CD8(+) Tr cells may lead to novel immunotherapy for immune inflammatory diseases.