Patients with genetic defects in cells of the TH17 subset of helper T cells suffer recurrent infections with Candida albicans and Staphylococcus aureus. In Nature, Zielinski et al. use whole-microbe pulsing of monocytes to stimulate naive and memory human CD4+ T cells to assess the polarizing conditions and effector characteristics induced by complex microbes. C. albicans–specific TH17 cells mainly produce both IL-17 and interferon-γ (IFN-γ), whereas S. aureus–specific TH17 cells mostly produce only IL-17 but can induce IL-10 after restimulation. IL-6, IL-23 and IL-1β contribute to the TH17 differentiation induced by each pathogen, but IL-1β is essential in C. albicans–induced TH17 differentiation. IL-1β is needed to counteract the inhibitory effect of IL-12, which is detected only in C. albicans cultures, to induce cells that produce both IL-17 and IFN-γ and to inhibit IL-10 production. IL-1β has similar effects on memory T cells, which suggests that IL-1β primes cells not only in lymphoid organs but also in target tissues.

Nature (1 April 2012) doi:10.1038/nature10957