[Utilidad del complejo soluble de ataque a membrana para determinar actividad clínica de la dermatomiositis y respuesta al tratamiento].

Introduction: Dermatomyositis is an autoimmune disease and the most common idiopathic inflammatory myopathy. During patient follow-up, determining biochemical parameters is required in order to assess for disease activity and treatment efficacy.

Objective: To determine the relationship between the degree of activation of the complement system through the soluble membrane attack complex (c5b-9), dermatomyositis clinical activity and its variations with conventional treatment.

Method: Forty-five patients with active and inactive dermatomyositis were studied. Chemical parameters and clinical severity were established and correlated with ELISA-determined C5b-9 serum levels.

Results: There was positive correlation between dermatomyositis cutaneous and muscular activity and C5b-9 serum levels, which was lower than with traditional biochemical markers. In the case of treatment response, C5b-9 showed significant reduction, similar to clinical severity; with biochemical parameters, the reduction was not significant at one month of treatment with systemic steroids.

Conclusions: Serum levels of C5b-9 levels of C5b-9 are higher in patients with dermatomyositis than in healthy subjects; dermatomyositis active and inactive cases were determined by means of their measurement. They can be a reliable parameter of therapeutic response, more accurate than muscle enzymes measurement, particularly creatine phosphokinase.