SEE PROFILE

Interaction between dendritic cells (DCs) and T cells is a pre-requisite for the initiation of a T cell response. The molecular nature of this interaction remains to be fully characterized. We report in this work that freshly isolated mouse splenic DCs and bone marrow-derived DCs express CD137 on the cell surface and in soluble form. Triggering CD137 increased the secretion of IL-6 and IL-12 from DCs. More importantly, infusion of an agonistic mAb to CD137 into naive mice enhanced the ability of DCs to stimulate T cell proliferation in response to both alloantigens and a nominal Ag in vitro. This enhancement of DC function is not mediated through activation of T cells, be-cause the effect was also observed in RAG-1 knockout mice that lack T cells. Our findings implicate CD137 as an impor-tant receptor involved in the modulation of DC function. The Journal of Immunology, 2002, 168: 4262–4267