PD-L1 or PD-L2 knockout further showed that reverse signalling through each ligand modulates distinct gene sets in FLS.<h4>Conclusions</h4>Cytokine-induced PD-L1 and PD-L2 expression is preserved in FLS from established RA but PD1-ligand signalling is altered, potentially contributing to the loss of immune regulation in RA. This evidence concerns the gene PDCD1LG2 and rheumatoid arthritis.