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.
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.
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.
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.