The IL-1 system in HIV infection: peripheral concentrations of IL-1β, IL-1 receptor antagonist and soluble IL-1 receptor type II

The proinflammatory cytokine IL-1β is thought to be involved in ongoing HIV disease. Furthermore, its naturally occurring inhibitors soluble IL-1 receptor type II (sIL-1RII) and IL-1 receptor antagonist (IL-1Ra) may play a pivotal role in regulating its biological action. To investigate the involvement of the IL-1 system we determined serum levels of IL-1β, IL-1Ra and sIL-1RII in 90 HIV⁺ patients. The obtained values were compared with markers of disease progression such as CD⁺ count, 5′-neopterin, β₂-microglobulin and soluble tumour necrosis factor receptors (sTNF-R) p55 and p75 and then compared with C-reactive protein (CRP), granulocyte count, lL-6 and TNF-α. While IL-1Ra concentrations increased significantly with progressive CDC disease stages, sIL-1RII and IL-1β were not altered in our cohort. IL-1Ra showed statistical relation to decreasing CD4⁺ lymphocytes and increasing 5′-neopterin, β₂-microglobulin, sTNF-R p55, sTNF-R p75. Furthermore, IL-1Ra correlated positively with serum IL-6, TNF-α, CRP and granulocytes. In contrast, sIL-1RII and IL-1β tended to show an inverse correlation or showed no significant relationship to all these parameters. Il-1β was measurable only in a limited number of samples. IL-1Ra showed a clear relationship to acute inflammatory events as well as to the different disease stages. Our data suggest a dissociation between IL-1Ra and sIL-1RII serum levels which may indicate that the two IL-1 binding proteins have different pathophysiological roles in HIV infection.