GZMB and synovial sarcoma: IL-21 was shown to have the potential to induce B cells that had granzyme B activity [67], and it was reported that T follicular helper (Tfh)-mediated IL21 expression induced granzyme B in CD5+B cells in SS [68], suggesting that as a cytotoxic serine protease, granzyme B is regulated by Tfh-mediated IL-21 production.