Prevalence of Novel Candidate Sjogren Syndrome Autoantibodies in the Penn Sjogren's International Collaborative Clinical Alliance Cohort

Purpose: To evaluate the prevalence of novel candidate autoantibodies associated with Sjogren syndrome (SS) and their ability to identify those with SS among participants with dry eye enrolled in the Sjogren's International Collaborative Clinical Alliance (SICCA) study at the University of Pennsylvania (Penn). Methods: All participants previously underwent a full ocular and systemic evaluation for possible SS as part of the SICCA study. An enzyme-linked immunosorbent assay was used to detect IgG, IgA, and IgM autoantibodies to salivary protein 1 (SP-1), parotid secretory protein (PSP), and carbonic anhydrase 6 from previously banked baseline serum samples from SICCA study participants enrolled at Penn. The prevalence rate of each autoantibody, calculated by considering the presence of any isotype as antibody positive, was compared between participants with dry eye with SS (n = 81) or without SS (n = 129) using the Fisher exact test. Results: The prevalence of SP-1 IgM autoantibodies was higher in those with SS compared with those without SS (14% vs. 5%; P = 0.03). Similarly, the prevalence of PSP IgA autoantibodies was higher in those with SS compared with non-SS dry eye participants (21% vs. 11%; P = 0.048). There was no statistically significant difference in the prevalence of carbonic anhydrase 6 autoantibodies between those with or without SS (15% vs. 20%; P = 0.36). Conclusions: In the Penn SICCA cohort, SP-1 IgM and PSP IgA autoantibodies were more prevalent in the serum of SS-related dry eye participants compared with those without SS. Further longitudinal studies are needed to determine the clinical significance of these findings.