NPM1-mutated acute myeloid leukemia of monocytic or myeloid origin exhibit distinct immunophenotypes.

Acute myeloid leukemia with mutated nucleophosmin (NPM1m+AML) is a heterogeneous entity. We investigated whether NPM1m+AML with monocytic or myeloid differentiation have distinct immunophenotype. The study included 160 NPM1m+AMLpatients and 178 AML patients without NPM1 mutation and recurrent cytogenetic abnormality (NPM1wt-AML). We analyzed the immunophenotype by flow cytometry. NPM1 mutation was detected by PCR. Compared with NPM1wt-AML patients, NPM1m+AML patients showed higher positive rates of CD33 and CD9 and lower positive rates of CD34, HLA-DR, CD7, CD15 and CD117 (all P<0.05). HLA-DR, CD64, CD14, CD11b, CD15, CD4, CD9 and CD10 were higher (P<0.001) and CD117 was lower (P<0.01) in monocytic NPM1m+AML compared with myeloid NPM1m+AML. Similar rates of lymphoid antigen (CD19, CD2, and CD7) and myeloid antigen (CD13, CD33) positivity were detected in monocytic and myeloid NPM1m+AML. Compared with NPM1wt-AML, CD34 expression was lower both in myeloid and monocytic NPM1m+AML subgroups, although HLA-DR was lower in NPM1m+AML compared with NPM1wt-AML only in myeloid subgroup. Comparisons of NPM1m+AML and NPM1wt-AML showed no differences in monocyte-associated markers such as CD14 and CD11b in myeloid and monocytic subgroup. Myeloid NPM1m+AML correlated with the female gender (P=0.001), lower WBC counts (P=0.04) and higher WT1 transcripts (P=0.006) compared with monocytic NPM1m+AML.These results suggested monocytic and myeloid-derived NPM1m+AML exhibit distinct immunophenotypes.