Immunoserological aspects of idiopathic inflammatory muscle disease

In the present study, the autoantibody profile of 31 Slovenian patients with idiopathic inflammatory muscle disease was estimated: 11 with polymyositis, 11 with dermatomyositis--both groups diagnosed according to the criteria of Bohan and Peter--and 9 with myositis-overlap syndromes. Autoantibodies against most relevant muscle specific (Jo-1, Mi-2) and non-specific antigens (PM-Scl, U1RNP, native Ro, Ro60, Ro52, and La) were detected with one or more detection techniques: counter-immunoelectrophoresis, enzyme-linked immunoassay, immunoblot and immunoprecipitation, each using different antigen preparations (native, recombinant). With counter-immunoelectrophoresis using a native antigen substrate (rabbit thymus extract), we were able to detect anti-PM-Scl antibodies more readily than with other techniques, probably due to conformational epitopes of native PM-Scl. Patients with this serological profile constituted a distinct group, sharing features of polymyositis and systemic sclerosis. Compared to previously reported data, the greater frequency of anti-Jo-1 found in all groups of patients (64-87% for PM, 18-20% for dermatomyositis and 33-44% for overlap syndromes) was probably due to the various methods used and the different clinical characteristics of patients. The greater prevalence of anti-Mi-2 antibodies in dermatomyositis patients (67%) and in particular in polymyositis patients (33%) and myositis-overlap syndromes (33%) seemed to be mainly due to methodological differences. A strikingly high prevalence of anti-Ro52 positive patients with polymyositis (55%), dermatomyositis (22%), and myositis-overlap syndromes (33%) was demonstrated, but was detected by only one technique. Moreover, concurrence with anti-Jo-1 antibodies was noted (69%).