Relation of antinuclear fluorescence patterns and titres to autoantibody prevalence

Different profiles of antinuclear antibodies (ANAs) have been found to be associated with different connective tissue diseases. Though several techniques have been developed to detect ANA, indirect antinuclear immunofluorescence (ANF) continues to be the most widely used and accepted. This study assesses the role of ANF as a screening test. The ANF patterns of 428 patients were studied. About 23% of patients with homogenous ANF patterns and 13% with speckled patterns were eventually shown to have raised anti-dsDNA titres. The percentage of patients harbouring raised titres of anti-dsDNA and the absolute titres were both seen to rise with the ANF titres. None of the patients with low ANF titres (1:40) harboured antibodies to extractable nuclea antigens (ENAs) whereas with increasing ANF titres the incidence of these autoantibodies was also seen to rise. Finally, it was noted that more than 80% of patients with high ANF titres demonstrated autoantibodies to ENA and/or dsDNA.