Cutting edge: a novel role for Fas ligand in facilitating antigen acquisition by dendritic cells.

Fas ligand (FasL)-expressing tumor cells are found to effectively mediate rejection of the coinoculated FasL negative parental cells while having no effect on the growth of histologically distinct tumor cells. These observations indicate that FasL induces a specific immune response against Ag derived from FasL-bearing tumors and suggest a possible role for FasL in tumor Ag presentation. Indeed, tumor cells expressing FasL can efficiently interact with dendritic cells (DCs) and this interaction requires the expression of membrane-bound FasL on tumors and Fas on DCs. Moreover, DCs cocultured with FasL-expressing tumors are able to elicit a tumor-specific immune response in vivo, suggesting that DCs acquire tumor Ag during the Fas/FasL-mediated DC-tumor contact. These results identify a novel role for FasL in augmenting tumor-DC interactions and subsequent tumor Ag acquisition by DCs, and suggest that FasL-expressing tumor cells could be used to generate tumor-specific DC vaccines.