IgA and IgG autoantibodies against alpha-fodrin as markers for Sjogren's syndrome

Objective. To determine the prevalence of IgA and IgG autoantibodies agains t alpha -fodrin in patients with primary and secondary Sjogren's syndrome ( SS) and controls. Methods, An ELISA detecting IgA and IgG antibodies against alpha -fodrin wa s developed. We examined the prevalence of IgA and IgG antibodies against a lpha -fodrin in patients with primary and secondary SS, systemic lupus eryt hematosus (SLE), and rheumatoid arthritis (RA) and blood donors. Results. IgA antibodies against alpha -fodrin were detected in 64% of patie nts with primary SS (n = 85), 47% of patients with secondary SS and SLE (n = 15), and 86% of patients with secondary SS and RA (n = 7). IgA autoantibo dies against alpha -fodrin were detected in only one of 160 sera obtained f rom blood donors and in one of 50 and 2 of 12 sera obtained from SLE and RA patients without sicca syndrome, respectively. The prevalence of IgG antib odies against alpha -fodrin in SS was lower. they were detected in 55% of s era obtained from patients with primary SS, 40% of patients with secondary SS and SLE, and in 43% of patients with secondary SS and RA. Three of 160 s era from blood donors and one of 50 and 5 of 12 sera from SLE and RA patien ts without sicca syndrome, respectively, contained IgG antibodies against a lpha -fodrin. Conclusion. IgA rather than IgG antibodies against alpha -fodrin are specif ic for and frequently observed in primary and secondary SS and are useful m arkers for this autoimmune disorder.