ACTIVATION OF ANTIGEN-INDUCED LYMPHOCYTE-PROLIFERATION BY INTERLEUKIN-15 WITHOUT THE MITOGENIC EFFECT OF INTERLEUKIN-2 THAT MAY INDUCE HUMAN IMMUNODEFICIENCY VIRUS-1 EXPRESSION

The newly identified cytokine, IL-15 enhanced antigen-induced prolifer ation of PBMC obtained from HIV-1-seropositive subjects, When compared to IL-2 which enhanced both spontaneous and antigen-induced lymphocyt e proliferative responses, IL-15 rarely increased spontaneous lymphocy te proliferation, Additionally, in cultures of lymphocytes obtained fr om 15 HIV-1-infected patients with < 300 circulating CD4(+) lymphocyte s/mu l IL-15 induced significant HIV-1 expression (46, 21, and 71 pg/m l) in only 3 of 15 experiments and IL-2 induced significant HIV-1 expr ession (range 16- > 5000 pg/ml) in 11 of 15 experiments (P < 0.01, Fis cher's exact test), Simultaneous assays of cytokine-induced spontaneou s lymphocyte proliferation and HIV-1 expression revealed similar dose- response relationships for induction of HIV-1 and lymphocyte prolifera tion by IL-2, Thus, IL-15 helps to correct the impaired proliferative response of CD4(+) lymphocytes from HIV-1-infected persons without the mitogenic effect of IL-2 that also may induce HIV-1 expression.