HK1 and systemic sclerosis: To confirm the discovery results, serum levels of antibodies against PRMT1, PRMT5, HK-1 and CD5L were then measured by ELISA in a primary validation cohort, including 90 patients with SSc, 30 patients with systemic lupus erythematosus (SLE), 8 patients with Sjögren’s syndrome (SjS) and 84 sex-matched and age-matched HC (online supplemental table S2, figure 1B).