We examined nine cases of adult non-T lymphoid leukemia to investigate the cell surface inducibility of interleukin 2 receptor alpha chain (IL-2R alpha) and beta chain (IL-2R beta) after in vitro culture with and without recombinant human interleukin-1 beta (rhIL-1 beta). Induction of IL-2R alpha was observed in four of six cases with precursor B-cell acute lymphoblastic leukemia (pre-B ALL) and in all of three cases with B-cell mature lymphoid neoplasm (two chronic lymphocytic leukemia and one leukemic phase of non-Hodgkin's lymphoma). All of the IL-2R alpha-inducible cases could express this spontaneously even without rhIL-1 beta, while IL-2R beta did not appear on leukemic cells from any of the cases tested. IL-2R alpha-inducible pre-B ALL cases displayed stem cell antigen CD34 and induced myeloid-associated antigen CD13 simultaneously. These results suggest that IL-2R alpha but not IL-2R beta is easily inducible in certain cases of mature B-cell lymphoid neoplasm and pre-B ALL with immature characteristics.