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 sho w that ST2L, a stable Th2 marker, is expressed at similar levels in Leishma nia 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 i s 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 o f IL-4.