Antibodies to extractable nuclear antigens in connective tissue disorders in India: prevalence and clinical correlations.

Antibodies to Extractable Nuclear Antigens (ENAs) namely Sm, nRNP, SS-A and SS-B were studied in 397 patients with various connective tissue diseases (CTD), 146 patients with inflammatory polyarthropathies, 16 cases of systemic vasculitides, and 39 normal subjects using counterimmunoelectrophoresis and double immunodiffusion methods. Anti-ENA antibodies were positive in 40.8 percent cases of Systematic lupus erythematosus (SLE) (n = 191), 36.4 percent of overlap CTD (OCTD, n = 44), 27.8 percent of Sjogren's syndrome (n = 18), 10.6 percent of progressive systemic sclerosis (PSS, n = 66) and 2.7 percent of rheumatoid arthritis (n = 111) patients. The correlation of these antibodies with disease features was done. The significant finding was negative association of anti-nRNP antibodies (when present alone) with renal involvement. Anti-Sm antibodies did not correlate with any disease feature. The other associations included correlation of anti-nRNP with pulmonary parenchymal lesions, anti-SS-A with serositis and pulmonary hypertension, and anti-SS-B with myocarditis and recurrent diarrhoea. We conclude that Anti-ENAs may correlate with certain subsets of these diseases but the subject is controversial.