Objectives: To analyse the prevalence of alpha-fodrin antibodies in patients with primary (pSS) and secondary Sjögren's syndrome (sSS) and the relation to clinical, serological and immunological features.
Methods: Serum IgA and IgG antibodies to the 120 kDa alpha-fodrin were determined by ELISA technique in 62 pSS patients and 28 sSS patients. Results were correlated with clinical symptoms and laboratory findings as well as with the HLA-DR genotype. Additionally, antibody concentrations were correlated with the numbers of peripheral blood mononuclear cells (PBMCs) secreting interleukin (IL)-6, IL-10, interferon-gamma (INF)-gamma, and tumour necrosis factor-alpha determined by ELISPOT analysis. Lymphocytes and monocytes were examined flow-cytometrically for the expression of activation markers. Healthy age- and sex-matched volunteers served as controls.
Results: The sensitivity of IgA and IgG alpha-fodrin antibodies was 35 and 31%, respectively, in pSS patients. In sSS patients, the sensitivity was 29 and 21%, respectively. In pSS patients with IgG antibodies, recurrent parotid swelling was significantly more prevalent. Also the number of INF-gamma secreting PBMCs and the percentage of CD4/CD71+ lymphocytes as well as CD14/HLA-DR+ monocytes were significantly increased in this group compared with alpha-fodrin-negative patients or with controls. Interestingly, these patients also had a shorter disease duration. No association of alpha-fodrin antibodies with the HLA-DR genotype was found.
Conclusion: Due to the low prevalence, serum antibodies to alpha-fodrin turned out to be of limited diagnostic value in our study. However, our data suggest that IgG antibodies to alpha-fodrin are indicative of clinical and immunological activity in pSS especially in patients with shorter disease duration and may thus serve as a marker of disease activity.