Removal of HLA-A,B antigens from platelets

Recent evidence suggests that HLA-A,B antigens present on human platelets, are acquired from plasma. Using hypertonic acid chloroquine (200 mg/ml, pH 5.0, 1 hr, 4 degrees C), we demonstrate elution of most or all HLA-A2 and HLA-B7,40 immunoreactive material from platelets. Corresponding antigens on human lymphocytes were not affected by this treatment. These findings are consistent with the hypothesis that HLA- A,B antigens are adsorbed onto platelet surfaces.