FCGR2B and myeloid sarcoma: Despite this, it is possible that females downregulate CD32b to a larger extent when B cells are activated (e.g. in CIS/MS patients) because of a potential effect of biallelic expression of immune response genes located on the X chromosome that regulate the CD32b signalling pathway, such as Btk (24, 54), or because of the influence of female sex hormones on B cells (15).