We observed that the mean fluorescence intensity (MFI) of TIM-3 on NK cells, the frequency of TIM-3+ NK cells, the MFI of PD-1 on NK cells and the frequency of PD-1+ NK cells in SLE patients were all significantly increased compared with that in the HC (all P < 0.05) (Fig. 1). Here, PDCD1 is linked to systemic lupus erythematosus.