CLINICAL-SIGNIFICANCE OF SPECIFIC AUTOANTIBODIES IN JUVENILE DERMATOMYOSITIS

Objective. To determine the prevalence and clinical association of myo sitis specific antibodies in an unselected group of patients with juve nile dermatomyositis (DM). Methods. The sera of 42 subjects, represent ing an unselected group of patients from a single center, with juvenil e DM and 7 others with idiopathic inflammatory myopathy (IIM) were exa mined for the presence of myositis specific antibodies by immunodiffus ion against calf thymus extract and immunoprecipitation with HeLa extr act. Results. Of the subjects with juvenile DM, only 2 had evidence of antibodies specific to myositis (anti-Mi2). Three other patients with juvenile DM had defined autoantibodies not usually considered to be s pecific to myositis. Two of the 3 subjects had anti-PM-Sd; both develo ped features of scleroderma after the juvenile DM remitted. The 5 subj ects with defined autoantibodies did not differ clinically from the re mainder of the subjects with the exception of the late development of scleroderma features in 2. Fourteen other subjects with juvenile DM ha d unidentified bands on immunoprecipitation, which may represent as ye t undiscovered myositis specific antibodies. No myositis specific anti bodies were detected in any of the 7 subjects with other IIM syndromes . Conclusion. Based on our findings, we do not recommend routine clini cal testing for these antibodies in children with typical juvenile DM. Further study of the unidentified bands seen in our subjects may lead to better understanding of the clinical groupings and etiopathogenesi s of childhood myositis.