RECIPIENT-REACTIVE ANTIBODIES OCCUR DURING DEVELOPMENT OF ACUTE GRAFT-VERSUS-HOST REACTION AFTER SMALL-BOWEL TRANSPLANTATION

After small bowel transplantation, not only rejection but also graft-v ersus-host reaction (GVHR) may occur, Donor T lymphocytes, transferred together with the graft, are a prerequisite for the development of GV HR, So far, however, little is known about the effector mechanisms in acute GVHR, It can be assumed that not only T lymphocytes but also oth er cells, i.e., B lymphocytes, monocytes/macrophages, and NK cells, to gether with inflammatory cytokines, are responsible for the lesions of recipient tissue. In the present study, the occurrence of recipient-r eactive antibodies after semisyngeneic small bowel transplantation was investigated to elucidate the role of B lymphocytes in GVHR developme nt, No antibodies reactive with recipient cells were detectable in ser um from untreated, nontransplanted rats, Five days after transplantati on, recipient-reactive antibodies started to appear in recipient serum , At the same time, a deposition of IgM antibodies became visible in t he liver and native intestine, which are target organs for GVHR, No an tibodies directed against either the donor strain or a third-party str ain were detectable in serum. We conclude that a synthesis of antibodi es against recipient tissue occurs during the development of GVHR. Whe ther these antibodies contribute to the disease remains unclear.