A BROADENED SPECTRUM OF JUVENILE MYOSITIS - MYOSITIS-SPECIFIC AUTOANTIBODIES IN CHILDREN

Objective. Myositis-specific autoantibodies (MSA) define relatively ho mogenous clinical and immunogenetic patient groups in adults with idio pathic inflammatory myopathies (IIM). This study explores the usefulne ss of MSA in defining groups of children with myositis. Methods. Sera from 77 children with myositis and other connective tissue diseases we re tested for MSA by immunoprecipitation and immunodiffusion. Clinical data were collected and analyzed. Results. The MSA anti-PL-12 (alanyl -transfer RNA synthetase), anti-Jo-1 (histidyl-tRNA synthetase), anti- signal recognition particle, and anti-Mi-2 were each identified in the sera of 12 children with IIM. In these patients, the clinical manifes tations, disease courses, and responses to therapy closely resembled t hose in adults with the same autoantibodies. Conclusion. These observa tions suggest that the clinical syndromes defined by particular MSA ar e similar in children and adults with IIM. By defining similar clinica l syndromes in children who have MSA, this study provides a basis for future studies of MSA in the idiopathic inflammatory myopathies of chi ldhood, which may be useful in predicting the clinical courses of a su bset of these patients and improving their therapy.