SERUM LEVELS OF INTERLEUKIN-1-BETA, TUMOR-NECROSIS-FACTOR-ALPHA, SOLUBLE INTERLEUKIN-2 RECEPTOR AND SOLUBLE CD8 IN SERONEGATIVE SPONDYLARTHROPATHIES

Seronegative spondylarthropathies are disorders with the same predispo sing antigen, namely HLA B27, a class I molecule of the HLA system. Th e mechanisms of the different diseases are unknown, and there is no pr oof of immune system participation. We have investigated patients with spondylarthropathies in order to search for an immunological componen t in the pathophysiology of these disorders, by measuring the serum le vel of two inflammatory cytokines - IL1beta and TNFalpha - by a radioi mmunological assay and the serum level of two soluble T cell activatio n markers - soluble IL2 receptor and soluble CD8 - by an enzyme-linked immunosorbent assay. The choice of soluble CD8 can be explained by th e strong link between HLA B27 and spondylarthropathies. Our series com pared 24 patients to 24 healthy matched controls. A similar IL1beta se rum level was observed in both groups, while in the patients there was a nonsignificant increase in the TNFalpha level, a significant decrea se in the soluble IL2 receptor level and a significant increase in the soluble CD8 serum level. The normal or moderately increased serum IL1 beta and TNFalpha levels in the disease group do not exclued a local r ole for these cytokines in the synovium or other inflammatory areas. H owever, we found a higher soluble CD8 serum level in the patient group . Most of these patients were in clinical exacerbation of their diseas e. As the serum level of soluble CD8 is well correlated with T CD8 lym phocyte activation, our data suggest that this lymphocyte subset is st imulated and consequently probably involved in seronegative spondylart hropathies.