Abstract: Objective To study the relationship between tumor necrosis factor(TNF) and the pathogenesis of polymyositis/dermatomyositis(PM/DM).Methods The serum levels of TNF-α were determined in 24 patients with PM/DM and 18 normal controls by double antibody sandwich ELISA method, and then their relationship with some clinically related laboratory parameters was analyzed.Results The results showed that the TNF-α was not detected in the control group,and the level of TNF-α was increased in 9 of 24 patients with PM/DM.In com parison with the group with elevated TNF-α to the group without,we found the group with elevated TNF-α had:(1) a higher level of urinary creatine(P<0.01). (2) a lower level of urinary creatinine(P<0.05). (3) increased level of ESR (P<0.01). (4) no difference in serum levels of CPK,LDH and AST.Conclusion Our results indicate that there is a relationship between TNF-α level and the disease activity of PM/DM,and TNF-α may play an important role in the pathogenesis of PM/DM.

Key words: Polymyositis, Dermatomyositis, Tumornecrosis factor