CD4 and infection: As CD4+ T cell-specific IL-4Rα-deficient mice remain positive for IL-4Rα expression on CD8 T cells, we could not rule out the possibility that IL-4Rα+ CD8+ T cells in CD4+ T cell specific IL-4Rα− deficient mice could have contributed to infection control, especially since CD8+ T cells have been implicated in protective immunity to VL (15, 30).