Hyporesponsiveness of memory CD4 T cells from rheumatoid arthritis patients upon TSLP-primed myeloid dendritic cell stimulation is at least partially reversed by PD-1 blockade. (A) Blockade of PD-1/PD-L1 interactions by anti-PD-1 antibody (1 μg/ml) in (TSLP-primed) myeloid dendritic cell (mDC) driven memory CD4 T cell activation from peripheral blood (PB) (n = 4, filled symbols) and synovial fluid (SF) (n = 4, open symbols) partially restores the T cell proliferative capacity. (B) Memory CD4 T cell hyporesponsiveness from SF (n = 4) is strongly reversed by interleukin-7 (IL-7), a cytokine that largely downregulates PD-1. Additional PD-1 blockade by anti-PD-1 antibody further reversed the downregulated proliferation. Statistical differences between these conditions were assessed using the paired-samples t-test. *P < 0.05 (statistically significant difference). PD-1, Programmed death 1; PD-L1, Programmed death ligand 1; TSLP, Thymic stromal lymphopoietin.