PDCD1 and systemic lupus erythematosus: The MFI of TIM-3 on TIM-3+PD-1+NK cells in SLE patients was significantly increased compared with that in the HC (P < 0.05) (Fig. 2f), whereas the MFI of TIM-3 on TIM-3+PD-1− NK cells did not differ significantly between the SLE patients and the HC (P > 0.05) (Fig. 2e).