Specificity of heteroantisera to human acute leukemia-associated antigens

Antisera have been raised to human leukemic blast cells from individual patients in mice rendered tolerant with cyclophosphamide to remission leukocytes from the same individual. 10 antisera were raised against acute myelogenous leukemia (AML) cells and 5 antisera were raised against acute lymphoblastic leukemia (ALL) cells. Antisera to AML cells were absorbed with ALL cells, and antisera to ALL cells were absorbed with AML cells. Unabsorbed and absorbed antisera as well as antisera raised in nontolerant mice were tested for cytotoxicity against various cells of a panel containing myeloblasts from 35 patients with AML, lymphoblasts from 7 patients with ALL, myeloblasts from 7 patients with chronic myelogenous leukemia (CML) in blast crisis, peripheral blood leukocytes from 12 patients with acute leukemia in remission and 30 nonleukemic patients, and nucleated bone marrow cells from 10 nonleukemic patients. Unabsorbed antisera to AML or ALL cells raised in tolerant mice were highly cytotoxic to leukemic blasts cells but significantly less cytotoxic to remission and control cells. Antisera to AML cells absorbed with ALL cells retained measurable cytotoxicity against AML cells but were not cytotoxic to ALL cells or control cells. Similarly, antisera to ALL cells absorbed with AML cells retained significant cytotoxicity only to ALL cells. Control antisera raised in nontolerant mice were cytotoxic to all cells tested. Although species specific, histocompatibility, differentiation, maturation, and cell cycle-associated antigens may be responsible in part for the cytotoxic activity of the unabsorbed antisera, the absorbed antisera are probably detecting antigens specific for their leukemic cell type.