Fig. 2

The PD-1 pathway in Inflammatory Arthritis. Despite increased expression of PD-1 by CD4+ and CD8+ T cells in the synovial tissue of RA patients, increased sPD-1 and PD-1 carrying EV could inhibit PD-1 mediated T cell suppression. Additionally, availability of PD-L1 by synovial DC could be limited due to increased expression of CD80 and the binding of CD80 to PD-L1 in cis, therefore, reducing the functionally available PD-L1