SUMMARYThe microabsorption technique developed in this laboratory has been utilized to demonstrate HL-A1, 2, 3, 9, 5, 7, and 8 antigens on frozen leukocytes, kidney, and spleen cells and on established lymphoid cell lines. No discrepancy was noted between HL-A phenotypes of 10 healthy donors determined by means of the standard lymphocytotoxicity test (LCT) and by means of microabsorption with frozen leukocytes. Most, but not all, HL-A antigens corresponding to those on lymphocytes could be demonstrated on kidney and spleen cells by this technique. It was also shown that cultured cells of established lymphoid cell lines possess their original HL-A antigens after long-term propagation