THE INTERLEUKIN (IL)-2 RECEPTOR-BETA CHAIN IS SHARED BY IL-2 AND A CYTOKINE, PROVISIONALLY DESIGNATED IL-T, THAT STIMULATES T-CELL PROLIFERATION AND THE INDUCTION OF LYMPHOKINE-ACTIVATED KILLER-CELLS

Late-phase human T-cell lymphotropic virus I-associated adult T-cell l eukemia cells express IL-2 receptors (IL-2R) but no longer produce IL- 2. We have reported that the IL-2-independent adult T-cell leukemia li ne HuT-102 secretes a cytokine, provisionally designated IL-T, that st imulates T-cell proliferation and lymphokine-activated killer cell act ivity. Stimulation of proliferation of the cytokine-dependent human T- cell line Kit-225 mediated by HuT-102 conditioned medium or by 3200-fo ld purified IL-T was not blocked by the addition of antibodies against IL-2 or IL-2R alpha submit. However, IL-T-mediated stimulation of thi s human T-cell line was inhibited by addition of Mik-beta-1, an antibo dy that binds specifically to IL-2R beta subunit. In addition, the act ivation of large granular lymphocytes to lymphokine-activated killer c ells mediated by IL-T-containing conditioned medium was not blocked by antibodies directed toward IL-2 or IL-2 alpha but was inhibited by an antibody to IL-2R beta, suggesting the requirement of this receptor s ubunit for IL-T action. This conclusion was confirmed using an IL-3-de pendent murine myeloid precursor cell line, 32D, that expresses H-2R a lpha and IL-2R gamma, but not IL-2R beta Neither IL-2 nor IL-T stimula ted 32D cell proliferation. However, after transfection with the gene encoding human IL-2R beta, 32D beta cells proliferated on addition of either cytokine. The IL-T-mediated stimulation of 32D beta proliferati on was inhibited by an anti-IL2R beta antibody but not by an anti-IL-2 antibody. Thus, the IL-T-mediated stimulation of T-cell and lymphokin e-activated killer cell activation requires the expression of the IL-2 R beta subunit.