Reactivity of Monoclonal Anti-HLA Antibodies with Blood Platelets

Binding pattern of mouse monoclonal antibodies specific for determinants on HLA-A, -B and -C glycoproteins were studied. The reactivity of the antibodies was quantitated by an “unlabeled antibody” immunoperoxidase technique. Blood platelets from 4 donors were used as target cells. The following results were obtained: 1) Observed binding patterns of monoclonal anti-HLA-A2 and anti-HLA-B7 was in agreement with results of conventional HLA-typing of lymphocytes; 2) Binding curves, obtained at different dilutions of a monoclonal antibody against a non-polymorphic “backbone” HLA-determinant, showed little variation between platelets of the different donors; 3) A a saturating amount of antibody, binding of monoclonal anti-HLA-A2 to platelets showed a gene-dose effect: platelets of an HLA-A2 homozygous individual bound approximately twice the amount of anti-HLA-A2 antibody compared to platelets from a HLA-A2 heterozygous donor.