CASP9 and systemic lupus erythematosus: Compared with CD56dimCD57+ NK cells in HCs, CD56dimCD57+ NK cells in SLE patients showed increased expressions of Cleaved-caspase 3 (MFI: 129 ± 26.8, n = 4 versus 238 ± 75.3, n = 6, P < 0.05, Fig. 3B) and Cleaved-caspase 9 (MFI: 181 ± 20.3, n = 8 versus 262 ± 69.3, n = 8, P < 0.001, Fig. 3C).