Differential effects of interleukin-12, interleukin-15, and interleukin-2 on human immunodeficiency virus type 1 replication in vitro

Abstract

Cytokines may have clinical utility as therapeutic agents for human immunodeficiency virus type 1 (HIV-1) infection and as an adjuvant for vaccines. The effect of interleukin-12 (IL-12) and IL-15 on in vitro HIV-1 replication was investigated. IL-12 and IL-15 at doses up to 10 ng/ml had little effect on basal HIV-1 p24 antigen production by chronically HIV-infected T (ACH-2) and monocytic (U1) cell lines. For ACH-2 cells stimulated with phorbol 12-myristate 13-acetate (PMA; 50 ng/ml), IL-12 and IL-15 significantly increased p24 antigen production by 20 and 30%, respectively (n = 6). In contrast, IL-12 and IL-15 (10 ng/ml) treatment of PMA-stimulated U1 cells decreased p24 antigen production by 16 and 15%, respectively (n = 6). We next studied the effect of IL-12 and IL-15 on HIV-infected peripheral blood mononuclear cells (PBMCs). In 10 HIV-seropositive patients' PBMCs cocultured with mitogen-activated HIV-seronegative donor cells, two patterns of p24 antigen production were observed in response to IL-2: low (p24 antigen production < 10(3) pg/ml; n = 8) and high (p24 antigen production > 10(3) pg/ml; n = 2) response. For the low-response pattern, IL-12 and IL-15 increased viral replication by 97-fold and 100-fold, respectively (P = 0.05 and 0.004, respectively). For the high-response pattern, both IL-12 and IL-15 suppressed HIV replication. The effect of IL-2, IL-12, and IL-15 on acute in vitro infection by HIV-1JRCSF was also examined. IL-12 did not increase p24 antigen production above basal levels while IL-2 and IL-15 significantly enhanced p24 antigen production (by approximately 2-fold). In conclusion, IL-12 and IL-15 may have differential effects on latent and acute HIV infection, and their ability to enhance HIV production may depend on cell activation. Thus, the use of these cytokines may be dictated by the clinical state of the patient.