MHC-RESTRICTION OF CYTOTOXIC ANTIBODIES T O BONE ALLOGRAFTS

Antibody-dependent cytotoxicity is commonly observed during rejection periods of parenchymal organ transplants. However, little is known abo ut the significance and mechanisms of a humoral immune response to bon e allografts. We evaluated the presence of cytotoxic antibodies in fif teen patients who received seventeen large frozen bone allografts. Don or specific antigens were identified by testing reactivity of recipien t serum against a cell panel of 44 different class I determinants. HLA class I mismatches were evaluated by tissue typing all donors and rec ipients. These data were correlated with the crossmatch test. Results suggest that large frozen bone allografts frequently evoke an antibody -dependent cytotoxicity in their host. In all but one patient, develop ment of one predominant donor specific idiotype of cytotoxic alloantib ody against the ''public'' domains of the MHC class-I molecule was not ed. This may provide the basis for a more practical approach to HLA ma tching in the transplantation of bone allografts in humans and therefo re decrease the relevance of potential immunologic rejection.