PDCD1 and systemic lupus erythematosus: As shown in Fig. 6, the frequency of TIM-3+PD-1+NK cells and the MFI of TIM-3 on TIM-3+PD-1+ NK cells were significantly reduced in the SLE patients who received treatment (P = 0.046 and P = 0.004, respectively), and no correlation was found between the MFI of PD-1 on TIM-3+PD-1+ NK cells with treatment.