Alteration of the HL-A antigenic site in situ.

The chemical nature of the HL-A antigenic sites on peripheral blood lymphocytes was studied by treatment of these cells with glycolytic enzymes and with sodium metaperiodate, and monitoring the residual antigen expression either by the lymphocyte cytotoxicity test or by quantitative microabsorption of monospecific anti-HL-A sera. Neither the gentle enzymatic nor the chemical treatment of lymphocytes altered expression of the HL-A antigens indicating that carbohydrates are not involved, in a major way, in the HL-A antigenic sites.