The amount of blood group A substance on platelets is proportional to the amount in the plasma

To investigate whether platelet ABO antigens are intrinsic to platelets or adsorbed from plasma, the amount of A-antigen on washed platelets was determined and related to the Lewis and secretor phenotypes, as these genes control the amount A, B. or H antigen present in plasma. The A-antigen on platelets was quantitated using a plate-let-erythrocyte mixed agglutination assay in 28 A, individuals of different Lewis and secretor phenotype. There was a direct correlation (r = 0.6, p