Histocompatibility in cardiac transplantation with particular reference to immunopathology of positive serologic crossmatch

Cardiac allografting was carried out in 33 patients during the past 2 years. Twenty-one (64%) of the patients are alive and others lived for different periods after transplantation. The number of HLA-AB and HLA-DR antigens matched or mismatched was not significantly different between the surviving and deceased patients. However, 100% (4 of the 4) of the patients with a positive serum crossmatch with donor T lymphocytes are deceased as compared to the 25% (7 of the 28) mortality rate for crossmatch-negative patients. All four of the deceased patients with a positive crossmatch had demonstrable deposition of immunoglobulins in the capillaries of the donor heart at autopsy, whereas no immunoglobulin or fibrinogen deposition was seen in the hearts of crossmatch-negative patients. Three of the four patients with positive crossmatches had sera cytotoxic to lymphocytes of more than 25% of the persons, of a 42 member panel, whereas in the remaining one the serum was cytotoxic to less than 5% of the panel members. In crossmatch-negative patients, the sera were cytotoxic to less than 20% of the panel members with one exception. The relevance of cytotoxic antibodies to lymphocytes of panel members, crossmatch, and tissue deposition of immunoglobulins is discussed.