Lymphocytotoxic antibodies and bone marrow grafts from HLA-identical siblings. I. HLA antibodies.

In a series of 30 bone marrow grafts (in 29 recipients) from HLA-identical siblings for aplastic anemia, no correlation was demonstrated between rejection and pregraft HLA antibodies (P greater than 0.50). However, after grafting, HLA antibodies persisted in nine cases and graft rejection occurred, whereas in all but one of the remaining eight cases the HLA antibodies disappeared and a permanent engraftment was observed (P = 0.0008). These results suggest a relationship between engraftment and persistence or disappearance of HLA antibodies as an indication of the level of immunosuppression obtained with the conditioning regimen.