CD19 and cancer: B cells are often recognised by the pan markers CD19 or CD20.83 Upon binding of an antigen compatible with their specific receptor, and supported by cytokines released from Th cells, B cells can differentiate to plasma cells and produce antibodies specific to the antigen that triggered their differentiation.84 However, B cells also act as antigen-presenting cells, promote differentiation of Th1 cells and Tcyt cells, and directly kill cancer cells through release of Granzyme B.85 These functions support a tumour-suppressive role for B cells.