Mouse Peyer's patches contain T cells capable of inducing the graft-versus-host reaction (GVHR).

The potential of cells from the Peyer's patches (PP) of normal adult DBA/2 Tru mice (DBA/2) to induce a graft-versus-host reaction when injected into (C57BL/6 Tru x DBA/2 Tru)F1 hybrid (B6D2F1) mice was studied. The injection of 10(6) to 10(7) DBA/2 PP or spleen cells i.p. into neonatal F1 mice produced a striking splenomegaly. Comparable doses of parental PP or spleen cells injected into a rear footpad of adult F1 mice also induced a marked enlargement of the draining popliteal lymph node. In addition, PP cells were also capable of producing a lethal runting syndrome when injected i.v. into sublethally irradiated adult F1 recipients. In all assays, injection of syngeneic B6D2F1 cells had little or no effect. Treatment of the DBA/2 PP cells with anti-theta serum and complement abolished their capacity to induce splenomegaly in neonatal F1 mice. The graft-versus-host reaction activity of the PP cells could also be eliminated by thymus deprivation of the donor DBA/2 mice. These data are contradictory to previous findings in which it was observed that mouse PP cells were unable to induce graft-versus-host reaction.