developed a model in which MS patient B cell engagement with a cognate T cell (CD40/CD40L and TCR/Ag-MHC class II recognition) in conjunction with IL-21 and especially IFNγ stimulation induces T-bet expression and subsequent CXCR3 upregulation (Figure 8C, left panel). This evidence concerns the gene CXCR3 and myeloid sarcoma.