From a disease perspective, it is notable that CD80 has been associated with a number of autoimmune diseases such as systemic lupus erythematosus (47) primary biliary cholangitis (48) and multiple sclerosis (49) Furthermore, unlike CD86 it also interacts with the PD-1 ligand PD-L1 indicating additional discrete regulatory functions for CD80 (50). This evidence concerns the gene CD80 and systemic lupus erythematosus.