Interleukin 1 inhibitor masks high interleukin 1 production in acquired immunodeficiency syndrome (AIDS).

Monocyte functions, including interleukin 1 (IL-1) production, have been shown previously to be impaired in acquired immunodeficiency syndrome (AIDS). We have fractionated culture supernatants from unstimulated peripheral blood mononuclear cells (PBMCs) to determine whether the low IL-1 activity in AIDS was due to the presence of IL-1 inhibitors. The results demonstrate that PBMCs from patients with AIDS produce increased amounts of IL-1 activity compared with those of controls together with marked increases (10- to 20-fold) in the amounts of 50,000-100,000 and 6000-9000 molecular weight (MW) factors which inhibit IL-1 activity. These inhibitors mask IL-1 activity measured in the standard thymocyte proliferation assay for IL-1. The 6000-9000 MW IL-1 inhibitor shows the greatest increase in all AIDS patients (n = 5) compared with that of controls (n = 7). This inhibitor may block the IL-1 dependent maturation of T lymphocytes in AIDS and thereby contribute to the immunodeficiency.