Antinuclear antibody determinations in Ro(SSA)-positive, antinuclear antibody--negative lupus and Sjögren's syndrome patients.

Antinuclear antibody determinations were performed on the sera of twenty-eight Ro(SSA)-positive patients, who failed to demonstrate significant antinuclear antibody titers on mouse liver, with the use of various heterologous and homologous substrates. These studies demonstrated the following: (1) The existence of substrate specificity among various tissues and cells employed in the detection of antinuclear antibodies in Ro(SSA)-positive patients. (2) The existence of a significant group of Ro(SSA)-positive lupus patients with prominent cutaneous findings and systemic disease who, despite the employment of a variety of antinuclear substrates, failed to demonstrate significant antinuclear antibody titer.