CD274 and synovial sarcoma: To investigate whether endogenous PD-L1 expressed in the SMG affects the pathogenesis of SS, we intraperitoneally (i.p.)-administered 200 μg of an anti-PD-L1 antibody, which blocks the interaction between PD-L1 and its receptors, or the isotype control, rat IgG2b, into 6 week-old female NOD/ShiLtJ mice every other day for a total of 4 times and analyzed the disease profiles in these mice.