Donor-specific transfusions in unrelated and related HLA-mismatched donor-recipient combinations.

The donor-specific transfusion protocol (DST) with (DST+I) or without Imuran has resulted in improved graft survival in one-haplotype-mismatched high-MLC-reactive donor-recipient combinations. In this study we have extended the use of donor-specific transfusions to unrelated individuals (group 1), distant relatives (group 2), and two-haplotype-mismatched siblings (group 3). All grafts in group 1 and group 2 are functioning. In group 3, one patient was lost from a myocardial infarct and one kidney was lost due to rejection. In vitro testing was performed using cryopreserved cells obtained prior to transfusion (t0), after the third transfusion (tt), and after transplantation (tx). We observed patient-specific suppression in tt plasma and nonspecific suppression by tx plasma. We also found ADCC-like activity in tx, but not in t0 or tt plasma in 2 out of 3 patients. The suppressor effect of tt plasma is mediated by IgG antibody and possibly reflects an antiidiotypic antibody.