Flow cytometry further revealed both increased PD-1 positive monocytes and elevated cellular PD-1 expression in PJI in peripheral blood (control: 48.0% vs explantation: 96.8%, p < 0.001; vs reimplantation: 84.5%, p < 0.001; Fig. 3C, E, F) and bone marrow specimens (control: 20.1% vs explantation: 55.7%, p = 0.003; vs reimplantation: 41.6%, p = 0.198; Fig. 3D, E, G). Here, PDCD1 is linked to juvenile polyposis syndrome.