SKELETAL-MUSCLE IMMUNE DEPOSITS IN SYSTEMIC LUPUS-ERYTHEMATOSUS - CORRELATION WITH HISTOLOGIC-CHANGES, AUTOANTIBODIES, AND CLINICAL INVOLVEMENT

Skeletal muscle biopsy and autopsy samples of 132 SLE patients were st udied by immunofluorescence and light microscopic techniques. Immune d eposits were compared to histologic abnormalities and clinical and ser ologic findings. Immune deposits with a mainly granular pattern were o bserved at different locations in 49 patients (37%). They correlated s ignificantly (p<0.001) with inflammatory myopathy, demonstrated in 33 (25%), with noninflammatory myopathy which occurred in 38 (29%) vascul itis, observed in 13 (10%), and with noninflammatory vasculopathy whic h was noted in 10 patients (8%). The correlation of muscle immune depo sits with anti-DNA antibodies was significant at p = 0.016. Anti-Sm an d anti-U1 RNP antibodies were associated significantly with the intens ity of immune deposits. Furthermore, a correlation of immune deposits with increased creatine phosphokinase and myopathic electromyogram, bu t not with evidence of clinical involvement, was shown. A key pathogen etic role of immune deposits in the development of skeletal muscle his tologic abnormalities in SLE was demonstrated.