[Immunophenotypic and clinical characteristic analysis of NPM1 mutated acute myeloid leukemia with a normal karyotype].

This study was purposed to compare the immunophenotypic and clinical characteristics of NPM1 mutated acute myeloid leukemia with a normal karyotype under the similar constituent ratio of FAB subtypes. Immunophenotyping and NPM1 gene mutation type-A,B and D and other leukemic related fusion genes were detected by multiparameter flow cytometry and real time RT-PCR or PCR, respectively. 77 AML patients with a normal karyotype (NK) and mutated NPM1 gene (NPM1m(+)AML) detected by immunophenotyping assay were included in this study. 55 cases without NPM1 mutation (NPM1m(-)AML) and with normal karyotype were served as negative control. The results showed that there was significant difference between NPM1m(+)AML and NPM1m(-)AML in terms of sex, white blood count, platelet counts, blast, WT1 expression level, FLT3-ITD mutation positive rate and response to treatment. The characteristic immunophenotype is lower expression of early differentiation-associated antigens (CD34, HLA-DR, CD117, CD38), lymphocytic antigens (CD7, CD4, CD19, CD2) and higher expression of CD33 and CD123 (P < 0.05). When above features was further analyzed between the M1/2 and M4/5 subgroups in NPM1m(+)AML patients, the M1/2 cases retained a higher frequency in women and a higher WT1 expression level (P < 0.05) . Monocytic differentiation-associated antigens including HLA-DR and lymphocytic antigens CD7 were higher expressed and CD117 was lower expressed in M4/5 subgroup (P < 0.05). It is concluded that under condition of similar constituent ratio of M1/2 and M4/5 subtype and normal karyotype, NPM1m(+)AML patients have higher WT1 expression level and better response to treatment. The major immunophenotype features of NPM1m(+)AML patients are lower expression of early differentiation antigens and lymphoid lineage antigens and higher expression of CD33 and CD123. Monocytic differentiation-associated antigens only higher are expressed in M4/5 cases when compared with M1/2 cases within NPM1m(+) AML patients.