Elevated immunoglobulin to tissue KLK11 in patients with Sjögren syndrome

Purpose: We have previously reported that mouse kallikrein (KLK) 22 in the lacrimal and salivary glands is an autoantigen that can induce primary Sjogren syndrome (SS) in rats. In this study, we determine whether the production of antibodies against tissue KLK is specific for SS and whether the antibody can be used as a biomarker for the diagnosis in humans. Methods: Sera from 11 patients diagnosed with SS, 8 patients with dry eye disease (DED), and 8 normal age/sex-matched controls (NL) were collected for detecting antibodies against tissue KLK1, KLK11, KLK12, and KLK13 by capture enzyme-linked immunosorbent assay. Results: Anti-KLK11 antibody was significantly higher in the SS than in the DED (P = 0.05) and NL (P < 0.01) groups, with no difference in the level of this antibody between the DED and NL groups. In addition, receiver operating characteristic analysis revealed that, at or above an optical density cutoff point of 0.2695, anti-KLK11 antibody has a sensitivity of 82% and a specificity of 94% to distinguish the SS group from the other groups. Conclusions: Our results suggest that anti-KLK11 might be a novel biomarker for SS in humans. Further investigation is required to confirm this finding and to establish the exact role of KLK11 in the pathogenesis of SS.