Defective T-cell response to PHA and mitogenic monoclonal antibodies in male homosexuals with acquired immunodeficiency syndrome and its in vitro correction by interleukin 2.

We studied the ability of phytohemagglutinin (PHA) and two anti-T-cell monoclonal antibodies OKT3 and Pan T2, to induce proliferation and interleukin 2 (IL2) production in peripheral blood lymphocytes (PBL) from 21 homosexual patients: 12 with Kaposi's sarcoma (KS), 4 with reactive lymphadenopathy, and 5 with opportunistic infections. All patients with KS and opportunistic infections had significantly lower mitogen-stimulated DNA synthesis, as compared to the controls, irrespective of the mitogen used (P less than 0.01). The patients with lymphadenopathy exhibited significantly lower responses only in the OKT3 assay as compared to normals (P = 0.009). The production of endogenous IL2 was significantly lower in PBL cultures from patients with KS and with opportunistic infections, irrespective of the mitogen used, as compared to healthy male controls, and also significantly lower in the Pan T2-stimulated cultures from patients with lymphadenopathy. The addition of highly purified IL2 was able to restore partially lymphocyte proliferation in vitro in the presence of these mitogens in all patients. Our studies demonstrate (1) that male homosexuals even without clinical manifestations of immunodeficiency frequently exhibit a proliferative T-cell defect when anti-T-cell monoclonal antibodies rather than PHA are used as mitogens, (2) that this proliferative defect is associated with defective IL2 production, and (3) that this defect is at least in part correctable in vitro by highly purified IL2.