CD19 and systemic lupus erythematosus: Rossi et al., revealed that the infusion of epratuzumab (anti-CD22 mAb) reduces not only the expression of CD22, but also the expression of other cell surface molecules, including CD19, CD21, and CD79b, on B cells [89], which may favor the efficient inhibition of pathogenic B cell functions in the treatment of systemic lupus erythematosus (SLE).