The abnormal signaling of the B cell receptor and co-receptors of lupus B cells

It is easily understood that studying the physiology and pathophysiology of the BCRtriggered cascade is of importance, particularly in such diseases as systemic lupus erythematosus (SLE) that are considered by many as a “B cell disease”. Even though B cells are not considered as the only players in lupus pathogenesis, and other immune and non-immune cells are certainly involved, it is the success of recent B cell-targeting treatment strategies that ascribe a critical role to the lupus B cell. •B cells are central to the pathogenesis of SLE. Lupus has been viewed as a “B cell disease”.•B cells from patients with SLE are hyperactive.•B cells from patients with lupus respond in an enhanced manner to antigen-receptor mediated stimulation.•B cell inhibitory co-receptors are deficient or function defectively (FcγRIIB1, CD72, CD22)•B cell signaling cytoplasmic signaling regulators (Lyn, PTEN, PTPN22) provide insufficient sighaling inhibition.