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.

Studies of an interleukin 1 inhibitor: characterization and clinical significance.

Supernatants from 24 h cultures of human peripheral blood mononuclear cells (PBMNC) were fractionated and tested for interleukin (IL-1) activity in the mouse thymocyte assay with phytohaemagglutinin (PHA). By the addition of individual supernatant fractions together with partially purified IL-1 to the thymocyte assay, we demonstrate the presence of strong inhibitory activity with a mol. wt of 5,000-9,000 and an isoelectric point of 4.5-5.6. The activity is both heat (56 degrees C) and acid (pH 1.5) resistant. This inhibitor has no detectable suppressive effect on optimal and suboptimal concanavalin A (Con A), pokeweed mitogen (PWM), and PHA responses of PBMNC. The action of the inhibitor appears to be specifically directed against IL-1 action on thymocytes and has no inhibitory effect on interleukin 2 (IL-2) activity. The findings show that adherent PBMNC produce both IL-1 and a factor which opposes IL-1 action on thymocytes but not on peripheral (mature) T cells. This factor may regulate T cell maturation, activation, and proliferation.