Includes abstract.Includes bibliographical references.Leishmania major is a protozoan parasite and infection in the human host causes severe cutaneous Leishmaniasis. The study aims to determine how signaling via the IL-4Rα on CD4+T cells causes susceptibility to L. major. We compared gene expression patterns early during infection in CD4+ T cells in the absence or presence of IL-4Rα signaling. Non-healer BALB/c mice with a deletion of the IL-4Rα on all cells (IL-4Rα-/-) or CD4+ T cells only (iLCKcreIL-4Rαlox/-) and their controls (wild-type (WT) C57BL/6, WT BALB/c and littermate IL-4Rαlox/-) were subcutaneously infected with L. major. As expected, the C57BL/6 “healer” mice produced a predominant TH1 response, whereas the iLCKcreIL-4Rα-/lox mice and susceptible BALB/c mice produced a TH2 response
