Lymphoma-associated and HL-A antigens in the mixed leukocyte reactivity between identical siblings

To distinguish between lymphoma-associated and HL-A antigens, studies of mixed lymphocyte and lymphocyte-tumor cell interactions with concurrent blood grouping and tissue typing were conducted in a large family which included a pair of identical twins, one of whom had lymphoma. Tumor cells, but not the patient’s own peripheral blood leukocytes, stimulated blastogenic responses in peripheral blood lymphocytes from the patient, from his identical twin, and from two other HL-A-identical siblings. This finding suggests that a non-HL-A, possibly tumor-associated, antigen was present on the surface of the lymphoma cells.