In vitro migration of L3T4+ cloned T cells to epidermis: possible role for keratinocyte-derived factors.

Three types of L3T4+ cloned T cells with different antigen specificities, auto-, allo-, and antigen-reactive, were characterized with respect to their migratory potential using an in vitro migration assay under agar gel. Autoreactive T cells, BB5, and alloreactive T cells, SK 1, both of which have been proved to be epidermotropic in vivo, showed specific directional migration to the epidermis, whereas no directional migration was seen with non-epidermotropic cloned T cells and freshly isolated lymph node T cells. Both BB5 and SK 1 cells were equally attracted to all the epidermal fragments tested regardless of their I-A antigens. The directional migration of BB5 cells to the epidermis was significantly inhibited by the co-cultivation with the epidermis, but not the dermis. Studies with cell lines, the conditioned media (CM), and recombinant interleukin (IL) 1, 2, and 3 revealed that BB5 cells were chemotactically attracted to a transformed keratinocyte cell line PAM212 and, to a lesser extent, to the CM from PAM212 and IL-2, but not to IL-1 and IL 3. These results suggest that epidermotropic T cells may be preferentially trapped in an area with a high concentration of keratinocyte-derived growth factors as well as IL-2.