Comparative analysis of autoantibodies against a-fodrin in serum, tear fluid, and saliva from patients with Sjögren's syndrome.

Objective: To evaluate levels of IgA and IgG antibodies against a-fodrin in serum, tear fluid, and saliva and compare them with anti-Ro and anti-La antibody levels in the same samples of patients with Sjögren's syndrome (SS).

Methods: Samples from 25 patients with SS (17 primary and 8 secondary), 8 patients with systemic lupus erythematosus (SLE), and 7 patients with rheumatoid arthritis (RA) as well as 20 healthy blood donor controls were collected. Antibodies were measured using ELISA.

Results: Although 40% of patients with primary SS had IgG anti-a-fodrin in their sera, it was also found in 36% and 32% of samples of their tear fluid and saliva, respectively. IgA a-fodrin antibodies were detected in 32% of SS sera, 20% of tear fluid samples, and 32% of saliva samples. Although the level of IgG anti-a-fodrin was significantly greater in serum, tear fluid, and saliva of SS patients compared to controls (p < 0.001), a significant difference was observed only in serum and saliva. While anti-Ro was detected in 48%, 56%, and 24% of serum, tear fluid, and saliva samples, respectively, anti-La was found in 40%, 44%, and 28%. Significant association was observed between serum IgG antibodies against a-fodrin and dry eye symptom score and rose bengal staining score. A negative association was also noted between tear IgA antibodies against a-fodrin and Schirmer I test.

Conclusion: Correlation of IgG and IgA antibodies against a-fodrin with the severity of eye involvement suggests that these autoantibodies may be considered activation markers of SS.