FCGR2B and systemic lupus erythematosus: Moreover, our findings indicate that the graded expression levels of FcγRIIB in B cell subpopulations (PCs > memory cells > naïve cells) dictate the outcomes of FcγRIIB-mediated inhibition independent of BCR and provide new insights into safe use of antibody targeted therapy in autoimmune diseases, e.g. SLE.