Elevation of serum soluble tumour necrosis factor receptors in patients with polymyositis and dermatomyositis

The aim of the study was, to examine the relationship between serum levels of soluble tumour necrosis factor receptors (sTNF-R) and the gene expressio n of two types of receptor for TNF (TNF-R) a 55 kDa receptor (TNF-R1) and a 75 kDa receptor (TNF-R2). in peripheral blood mononuclear cells (PBMC) fro m patients with polymyositis and dermatomyositis (PM/DM). Soluble tumour ne crosis factor receptor (sTNF-R1) and soluble tumour necrosis factor recepto r 2 (sTNF-R2) levels in sera from patients were measured by enzyme-linked i mmunosorbent assay. Expression of TNF-R1 and TNF-R2 mRNAs in PBMC was analy sed by Northern blotting. Serum sTNF-R1 and sTNF-R2 levels were elevated si gnificantly in 25 patients with active-stage PM/DM: compared to those in 18 patients with inactive-stage PM/DM and 32 normal controls. Serum concentra tions of sTNF-R1 and sTNF-R2 were correlated with PM/DM disease activity. T NF-R1 ene expression was enhanced in freshly isolated PBMC from patients wi th active-stage PM/DM. In contrast, TNF-R2 mRNA was expressed constitutivel y in patients with active-stage PM/DM and in normal controls. The expressio n of TNF-R1 and TNF-R2 mRNAs in PBMC and elevation of their soluble forms i n the sera of patients with active-stage PM/DM suggest increased proteolyti c cleavage of cell surface TNF-R from PBMC in patients with active-stage PM /DM, and that sTNF-R may regulate TNF-x-mediated muscle fibre damage in PM/ DM.