Production of and in vitro response to interleukin 2 in the acquired immunodeficiency syndrome

Abstract

To test the hypothesis that deficient interleukin 2 (IL-2) secretion may underlie the impaired capacity of T cells from patients with Acquired Immunodeficiency Syndrome (AIDS) and the AIDS-related complex (ARC) to generate the macrophage-activating lymphokine, gamma interferon (IFN-γ), we used five specific microbial antigens to examine IL-2 production. Mononuclear cells from only one of 32 (3%) AIDS patients secreted normal levels of IL-2, and 21 (66%) failed to produce any detectable IL-2. For 36 ARC patients, IL-2 generation was normal in nine (25%) and absent in 11 (31%). Given these results, recombinant (r) IL-2 was tested for its capacity to stimulate or enhance IFN-γ production. rIL-2 (10 U/ml) alone stimulated cells from controls, ARC, and AIDS patients to secrete 93 ± 25, 99 ± 33, and 7 ± 3 U/ml of IFN-γ, respectively. rIL-2 (10 U/ml) plus antigen induced no change in mean IFN-γ levels for controls, a 4.4-fold increase for 17 AIDS patients (16 ± 16 vs. 71 ± 21 U/ml), and a 7.2-fold increase (18 ± 5 vs. 130 ± 27 U/ml) for 19 ARC patients with abnormal IFN-γ generation to antigen alone. Individual responses indicated that six of the 17 (35%) AIDS patients with opportunistic infections and 12 of the 19 (63%) with ARC were apparent responders to 10-100 U/ml of rIL-2. These results (a) document profound impairment in antigen-induced IL-2 secretion by AIDS and ARC T cells, (b) indicate that, in vitro, mononuclear cells from certain patients can respond to rIL-2 with enhanced IFN-γ production, and thus (c) suggest that in selected patients rIL-2 might have a potentially beneficial therapeutic (AIDS) of prophylactic (ARC) effect against opportunistic infections.