Plasma levels of interleukin-1-alpha in rheumatoid arthritis.

Interleukin-1-beta (IL-1 beta) has been implicated as an inflammatory mediator in rheumatoid arthritis (RA) but little is known about the related cytokine, IL-1 alpha, in this disease. IL-1 alpha has biological properties similar to IL-1 beta but, unlike IL-1 beta, remains mostly cell-associated. In this study plasma IL-1 alpha was measured by radioimmunoassay in patients with RA and in healthy controls. Plasma levels were compared with conventional measures of disease activity. The mean levels in the two groups were not significantly different and, within the patient group (n = 53), the only significant cross-sectional correlation was between plasma IL-1 alpha and ESR. In longitudinal studies, some individual patients had plasma IL-1 alpha levels that correlated with different measures of disease activity. We conclude that while IL-1 alpha may be involved in the immunopathogenesis of RA, its measurement in plasma seems to offer little of clinical value.