Profound effect of the absence of IL-4 on T cell responses during infection with Schistosoma mansoni

Abstract

T cell responses of interleukin (IL)-4−/− and wild-type (WT) mice infected with the helper T cell 2 (Th2) response-inducing pathogen Schistosoma mansoni were compared. As expected, given the important role of IL-4 in Th2 response induction, the absence of IL-4 resulted in diminished Th2 responses, apparent as reduced production of IL-4, -5, and -10 by CD4+ cells isolated from the spleens of infected IL-4−/− mice. Surprisingly, these cells produced significantly less interferon (IFN)-γ and proliferated less than did those from infected WT mice after T cell receptor ligation. CD8+ cells isolated from infected IL-4−/− mice also produced less IFN-γ than WT CD8 cells, although there was no difference in the proliferative responses of these cell populations. After infection, spleens of infected IL-4−/− mice did not enlarge to the same extent as those of WT mice, and attrition of the CD8+ cell population within this lymphoid organ was noted. Taken together, the data indicate that in addition to inhibiting Th2 response development, the lack of IL-4 during schistosomiasis significantly affects additional aspects of T cell responses.