Prevalence of antibodies against α-fodrin in Sjögren's syndrome: Comparison of 2 sets of classification criteria

Objective. To compare the prevalence of antibodies against α-fodrin in Sjögren's syndrome (SS) classified according to San Diego and European Community Study Group (ESG) criteria. Methods. The prevalence and mean concentrations of IgA and IgG autoantibodies against α-fodrin were determined and compared in patients with SS classified either according to San Diego criteria or to criteria of the ESG by ELISA. Results. IgA antibodies against α-fodrin were detected in 88% and IgG antibodies against α-fodrin in 64% and either of these antibodies in 93% of 85 patients classified according to San Diego criteria. Antibodies against Ro were present in 38% of these sera. IgA antibodies against α-fodrin were detected in 61%, IgG antibodies against α-fodrin in 51%, and any of these antibodies in 73% of 51 patients classified according to the ESG criteria. The mean concentrations of both IgA and IgG antibodies against α-fodrin that seem to correlate with disease activity were higher in patients classified according to the San Diego criteria. Conclusion. Antibodies against α-fodrin are detectable in almost all sera obtained from patients with SS classified according to the San Diego criteria and are significantly more prevalent than antibodies against Ro. The lower prevalence of the autoantibodies in patients classified according to the ESG criteria reflects the lower specificity of these criteria for SS.