Variable capacity of L3T4+ T cells to cause lethal graft-versus-host disease across minor histocompatibility barriers in mice.

Highly purified populations of L3T4+ and Lyt-2+ T cell subsets were compared for their capacity to cause lethal GVHD in six different H-2-compatible, multiple minor histocompatibility antigen-different murine strain combinations. In four of these combinations (C3H.SW----B6, DBA/2----B10.D2, B10.BR----CBA, and B10.S----SJL), lethal GVHD appeared to be caused almost entirely by Lyt-2+ cells; the injection of L3T4+ cells resulted in low mortality even when these cells were presensitized to the recipient antigens. In the remaining two combinations (B10.D2----DBA/2 and B10.D2----BALB/c), L3T4+ T cells were able to cause a high incidence of GVHD and were more potent than the Lyt-2+ cells. The implications of these findings are discussed.