The role of class I MHC products in polyclonal activation of CTL function

The generation of CTL function by agents such as lectins, oxidative chemicals, or serum components has been regarded as independent of class I MHC products, because the CTL thus generated are able to lyse virtually any allogeneic target. However, we show here that CTL activation by lectin requires interaction of the pre-CTL with a class I MHC product on the lectin-presenting cell. The lectin-presenting cell can be an irradiated syngeneic or allogeneic spleen cell or, alternatively, lectin can be seen on a neighboring pre-CTL. In either case, there is an absolute requirement for simultaneous (although probably unlinked) perception of a class I MHC product. These results suggest that restricted clonal CTL activation by antigen, and polyclonal activation by so-called "nonspecific" mitogenic agents, may proceed through similar if not identical pathways.