A central role for IL-2 in fate determination of mature T cells--I: role in determining the Th1/Th2 profile in primary T cell cultures.

IL-2 signaling appears to play a significant role in enabling the synthesis of T(h)2 cytokines in an in vitro system for studying primary T cell responses. When T cells from C57BL/6J or BALB/c strains of mice were activated in vitro and re-stimulated through their TCR complex 48 h later, CD4(+) T cells producing the T(h)2 cytokines IL-4 and IL-10 were found only when IL-2 was present. IL-2 also enhanced IFN-gamma synthesis in C57BL/6J cells but not in BALB/c cells. By up-regulating production of anti-inflammatory T(h)2 cytokines during a primary response, IL-2 may play a critical role in limiting T(h)1-mediated responses.