Indeed, parallel in situ immunohistochemical and in vitro studies in cultured SGECs, have shown that they are suitably equipped to mediate the recruitment, activation and differentiation of immune cells in SS,1 whereas they have also been shown to mediate the activation and differentiation of CD4+-T cells.6–8 Furthermore, SGECs obtained from SS patients have been shown to express functional CD40 molecules and BAFF cytokine,9,10 which is essential for B cell survival, activation and differentiation. The gene discussed is TNFSF13B; the disease is synovial sarcoma.