TNF and systemic lupus erythematosus: Studies in patients with systemic lupus erythematosus had shown that TNF-α boost PD-L1-expression in monocytes (18) and this upregulation is likely to occur through TNF-α-mediated activation of NF-κB and ERK1/2 pathways as deciphered from studies in human colon cancer HCT116 cells (19).