Current data suggest that abnormal APCs functions may be involved in the pathogenesis of SLE because the unusual functions of APCs may downregulate the expression of PD-L1 on their cell surface and result in failed antagonization of T cell signaling transduction mediated by CD80/CD86 and overactivation of effector T cells, thereby leading to lupus onset [93]. The gene discussed is CD80; the disease is systemic lupus erythematosus.