PDCD1 and systemic lupus erythematosus: The expression of PD-1 in TILs and PD-L1 in tumor cells was similar in patients with pre-existing RA, SLE and in DLBCL controls, whereas the expression of PD-L1 in TILs was significantly higher in the DLBCL controls compared to the RA-DLBCL group and close to significantly higher than the SLE-DLBCL group.