Model: WNT5A and FZD5 as modulators of the interplay between antigen-presenting cells and T lymphocytes. Toll-like receptor–induced, NF-κB–mediated activation of human antigen-presenting cells (APCs) leads to transcription of WNT5A, which, released or cell surface bound, is able to interact with FZD receptors (eg, FZD5). WNT5A and FZD5 regulate the microbial-induced IL-12 response in an autocrine manner and thereby prime specifically activated T lymphocytes for IFN-γ release. In addition, since lymphocytes also express FZD5, a paracrine effect of WNT5A on these cells directly regulating the IFN-γ response is possible. Reagents used to develop this model are indicated by and in the affected pathways.