Complement‐Fixing Platelet Iso‐Antibodies in Serum of Transfused Persons. Correlation of Antibodies with Platelet Survival in Thrombocytopenic Patients

Sera from 172 patients who had received an average of 34 transfusions per patient were assayed for platelet antibodies using a complement fixation technic. Fifteen patients formed a total of 31 antibodies. Eighteen of these were identified as reacting with six specific platelet antigens which were present in from 3 to 49 per cent of the general population. The antigens are common to leukocytes, but not erythrocytes, and are genetically determined. No antibodies were found in serum from 55 non‐transfused persons. The probability of antibody formation increased with repeated antigen exposure. Stored whole blood was at least as effective as platelet concentrates in provoking antibodies. There was a significant relationship between the presence of complement fixing platelet antibodies and the occurrence of “fever‐chill” transfusion reactions. In three patients it was possible to correlate the efficacy of platelet transfusion therapy with the antigen content of infused platelets.