PDCD1 and Autoimmunity: Recently, in addition to a link with PD-1, PD-L1 was found to interact with the CD80 co-stimulator T-cell receptor, resulting in the disruption of the PD-L1/PD-1 binding on mature primary dendritic cells, in the restriction of PD-1-positive T-cell function, and in a exacerbation of autoimmunity [12].