CD19 and systemic lupus erythematosus: Patients with autoimmune conditions such as systemic lupus erythematosus (SLE) [7], RA [9], primary Sjögren′s syndrome [10], ANCA-associated vasculitis [11], and Systemic Sclerosis [12,13], have been shown to demonstrate altered numbers and/or function of circulating CD19+CD24hiCD38hi B cells.