To evaluate the clinical significance of antibodies to native or denatured (anti-n or anti-d) 60- or 52-kd Ro/SS-A proteins (60K or 52K) in Sjögren's syndrome (SS).
The presence of antibodies to denatured and native Ro/SS-A proteins was determined by immunoblotting and immunoprecipitation, respectively. Salivary gland dysfunction was evaluated by salivary function scintigraphy.
The incidence of anti-d-60K without anti-d-52K was lower among patients with systemic lupus erythematosus with SS (SLE/SS) and among those with primary SS, compared with patients who had SLE without SS, whereas anti-d-52K without anti-d-60K was more common in SLE/SS patients and primary SS patients than in SLE patients without SS. All of the patients with anti-Ro/SS-A had anti-n-60K. Serologic abnormalities and salivary gland dysfunction were associated with anti-n-60K in SS, whereas Hashimoto's thyroiditis in SS was related to anti-d-60K. Anti-d-52K was not associated with any extraglandular or glandular symptoms in SS.
The data indicate that anti-n-60K, which appears to recognize conformational epitopes, is associated with clinical features of SS characterized by glandular dysfunction.