CR2 and systemic lupus erythematosus: CD11c+ABCs are characterized by phenotypic markers including CD11c+, CD11b+, CD21-/low, CD23low (24, 25), which are notably expanded in the peripheral blood of patients with several autoimmune diseases, including systemic lupus erythematosus (SLE) (49, 50), RA (25) and multiple sclerosis (MS) (51).