CSK and systemic lupus erythematosus: CSK is associated with autoimmunity as higher levels in early stages of B cell maturation increase the number auto-reactive B cells and autoantibody production [43] and contrary to our study, was significantly downregulated in a pilot proteomic study by Zhou et al. [44], which had a cohort of SLE mostly enriched with cutaneous disease, the observed reduced CSK expression may reflect the differing treatment paradigms of skin versus systemic disease but may also reflect the variation in disease pathogenesis of SLE.