PDCD1 and systemic lupus erythematosus: Further analysis of the expression of PD-1 and TIM-3 on these NK cells found that the MFI of TIM-3 on TIM-3+PD-1+NK cells and the MFI of PD-1 on TIM-3+PD-1+ and TIM-3−PD-1+NK cells were significantly increased in SLE patients compared with the HC.