Abstract: Objective To explore the changes of KIR receptor and function of NK cells and CTL cells in patients with acquired hemophagocytic lymphohistiocytosis（HLH）. Methods The data of CD8⁺T cell function and KIR receptor and function of NK cells and CTL cells in 26 patients with HLH from February 2018 to February 2021 were collected retrospectively,and 17 healthy subjects were used as controls. The statistical analysis was carried out between the two groups. Results The proportion of lymphocytes and NK cells in patients with HLH were significantly lower than those in the control group（33.18±1.939 vs. 18.43±2.382,P<0.000 1;20.38±2.090 vs. 7.654±1.634,P<0.000 1）. The proportion of CTL cells was higher than that in the control group {45.5（35.275,50.375） vs. 35.2（30.2,37.9）,P=0.005}, but there was no significant difference in the proportion of T cells between the two groups（P=0.513）. Compared with the control group（0/17）,the gram-restricted expression of KIR receptor in NK cells increased significantly（7/26,P=0.031 0）; compared with the control group,the expression of Perforin in HLH group was decreased{93（67.35,97）vs. 96.6（95.1,97.8）, P=0.016 5}, but the expression of GranzymeB in the two group was no statistically different（P=0.871 7）. The expression proportion of Perforin and GranzymeB was not significantly different in CTL cells between the two groups（P=0.320 7,P=0.621 9）. Conclusion The pathogenesis of secondary HLH has no significant relationship with the expression of Perforin and GranzymeB in NK cells and CTL cells. The detection of Perforin can quickly exclude the deletion of PRF1 in primary HLH.

Key words: Acquired hemophagocytic lymphohistiocytosis, KIR receptor, The function of NK cells, CTL cells, Flow cytometry