[Correlation of NK cell RIPK1 with Prognosis of Acute Myeloid Leukemia Patients with FLT3-ITD Mutation].

OBJECTIVE

To investigate the correlation of NK cell receptor-interacting serine/threonine kinase 1（RIPK1） activity and expression with prognosis of acute myeloid leukemia (AML) patients with FLT3-ITD mutation.

METHODS

A total of 132 AML patients with FLT3-ITD mutation and 136 AML patients with FLT3-WT were selected. Clinical data and the number, length and rearrangement ratio of FLT3-ITD mutations were collected. The ratio of CD4 T cells, regulatory T cells（Tregs）, CD8 T cells, B cells, natural killer cells（NK cells） and macrophage in peripheral blood（PB） were analyzed by flow cytometry. Correlation of NK cell ratio with FLT3-ITD mutation number, length and rearrangement ratio was analyzed by Pearson correlation analysis. Western blot and RT-qPCR were used to detect RIPK1 protein and mRNA levels in NK cells, respectively. Plasma RIPK activity was detected by ELISA, and Pearson corre-lation analysis was performed for the correlation of RIPK with FLT3-ITD mutation number, length and rearrangement ratio. Kaplan-Meier curve was used to analyze the survival rate of AML patients with FLT3-ITD mutation.

RESULTS

Compared with AML patients with FLT3-WT, the white blood cell count in patients with FLT3-ITD mutation significantly increased, PB and BM blasts significantly decreased. There was no significant change in PB CD3 T cells, Tregs, CD8 T cells, B cells, M1 and M2 type macrophage of AML patients with FLT3-WT and FLT3-ITD mutation；Compared with AML patients with FLT3-WT, CD4 T cells significantly decreased, NK cells significantly increased in AML patients wtih FLT3-ITD mutation. NK cells ratio in AML patients with FLT3-ITD mutation significantly positively correlated with the number of FLT3-ITD mutations and rearrangement bases. Plasma RIPK1 activity, RIPK1 protein and mRNA levels in NK cells of AML patients with FLT3-ITD were significantly lower than those of AML patients with FLT3-WT, and negatively correlated with the number of FLT3-ITD mutations, the length of rearranged bases (≥52 bp) and the ratio of rearranged bases. The survival rate of AML patients with FLT3-ITD mutation in low RIPK1 activity after Rydapt treatment was significantly higher than that in high RIPK1 activity.

CONCLUSION

The prognosis of AML patients with FLT3-ITD mutation closely relates with plasma RIPK1 activity and RIPK1 expression in NK cells.