Self-reactive T cells. IV. Self-reactive T cells induce polyclonal differentiation of IgM-producing B cells in vivo and in vitro.

Intravenous injection of lymphoblasts (generated in vitro by different T- or B-specific mitogens) induced a polyclonal activation of IgM-producing B cells in vivo in the spleens of syngeneic recipient mice. This polyclonal differentiation of host-derived B cells to IgM-producing plaque-forming cells was stimulated by host-derived self-reactive T cells activated in the splenic lymphoid cell population in response to the syngeneic lymphoblast graft. We found a stable factor in the supernatants of cultures of proliferating self-reactive T cells that induced (antigen-independent) polyclonal maturation, but not proliferation of IgM-producing B cells.