Expression of Th2 cytokines and the stable Th2 marker ST2L in the absence of IL-4 during Leishmania major infection.

In this study we characterized Th2 responses in the absence of IL-4. We show that ST2L, a stable Th2 marker, is expressed at similar levels in Leishmania major-infected IL-4-deficient (IL-4(-/-)) and wild-type BALB/c (IL-4(+/+)) mice. Th2 cytokines are secreted by in vivo differentiated lymphocytes in response to specific activation in the absence of IL-4. Although IL-13 is produced, its neutralization did not alter the outcome of infection. Thus, we demonstrate that Th2 differentiation as assessed by the expression of ST2L and the production of Th2 cytokines can occur in vivo in the absence of IL-4.