Tolerance induction to an alloepitope involves antibodies interacting with the T cells activated by the alloepitope

Hyperimmunization of BALB/c mothers with Ab1 (BALB/c anti-C57BL/6) antibody can alter the T-cell repertoire of the syngeneic offspring called BALB/c-p-Ab1. The latter are rendered tolerant to specific alloantigens and are therefore resistant to graft-versus-host disease (GVHD), when challenged 24-48 hours after birth with allogeneic spleen cells. These offspring appear to express cell structures recognized by hyperimmunized mothers and which are presumably the T-cell counterparts of Ab2. Our data suggest that tolerance induction in our mouse model may be modulated by an idiotype network acting during foetal life. The factor modifying the foetal cell repertoire is identified as Ab2 (BALB/c anti-Ab1) antibody transplacentally transmitted from mother to foetus, which seems to carry an "image" of the GVHD-inducing alloepitope and can induce a "GVHD-like" syndrome when passively injected intraperitoneally in normal BALB/c newborn mice.