Expression Of FLT3 And Point Mutation In Tyrosine Kinase Domain In Acute Myeloid Leukemia Patients

【Objective】To investigate the difference of the expression of FLT3 in bone marrow mononuclearcells between acute myelogenous leukemia(AML) patients and normal persons, and to evaluate the prevalence of a novel FLT3 activating point mutation in tyrosine kinase domain (TKD) in AML patients.【Methods】The expression of gene FLT3 in bone marrow mononuclearcells is molecule CD135. After marking bone marrow mononuclearcells of newly treated AML patients and normal persons with CD135 antibodies, we used three-color flow cytometry analysis and direct immunofluorescence analysis to evaluate differences of the expression of FLT3 in bone marrow mononuclearcells between AML patients and normal persons. And then we detected the point mutation in TKD of FLT3 in bone marrow mononuclearcells in 30 AML patients with the method of RT-PCR and digestion of DNA with restriction enzyme, and try to find out the clinical relevance.【Result】There are significant differences of positive ratio of CD135 in bone marrow mononuclearcells between AML patients (63.2%±25.4%) and normal persons (1.13%±0.21%)(p<0.05). Among 30 AML patients, FLT3-TKD point mutation exists in 3 patients (positive ratio is 10%), 2 of whom achieved complete remission after therapy (CR rate is 66.7%). Among other 27 AML patients, 25 patients accepted therapy, 21 of whom achieved complete remission (CR rate is 84%). Thus there are no significant differences of CR rate between them (p>0.05).【Conclusion】Expressions of gene FLT3 in bone marrow mononuclearcells of AML patients are significantly higher than normal persons. Among AML patients, the positive rate of point mutation in TKD is about 10%. The differences of CR rate between point mutation positive patients and negative patients should be studied in further.