Objective: To analyze the immunophenotype and leukemia associated immunophenotype (LAIP) of leukemia cells from patients with acute myeloid leukemia (AML) in minimal residual disease (MRD) detection.
Methods: Four-color multiparametric flow cytometry (FCM) with CD45/SSC gating was used to determine the expression of the following antibodies of CD7, CD117, CD33, CD34, CD10, CD19, CD56, CD38, CD13, CD14, CD64, CD9, CD16, CD2, CD5, CD11b, CD123, HLA-DR in 610 AML patients and 20 normal bone marrow (NBM) samples.
Results: The mean percentages of CD34+ and CD117+ side scatter low (SSC(low)) cells in NBM mononuclear cells (BMMNCs) were (0.35 +/- 0.15)% and (0.76 +/- 0.31)%, respectively. The majority (84% -95%) of CD34+ SSC(low) cells co-expressed CD13, CD33, CD38, CD117 and HLA-DR. 33% and 20% of CD34+ SSC(low) cells were CD15+ and CD9, respectively. Only a small proportion (< 10%) of CD34 SSC(low) cell co-expressed CD11b, CD56, CD19 and CD64, while co-expressed CD7 was 12%. In CD117 SSC(low) cells, the relative proportions of CD19+, CD11b+, CD56+ and CD7+ were less than 10%, while CD9+ was 14%. CD38+ and HLA-DR+ were 87% and 91%, respectively. The expressions of CD15, CD34, CD13 and CD33 on CD117 SSC(low) cells were between 30% and 50%. In AML patients, most cases were CD117+ (95.08%), CD38+ (94.74%), CD9+ (84.93%), CD33+ (84.60%), HLA-DR+ (77.23%) and CD13 (75.25%). The proportions of CD64+ and CD34+ were 64.41% and 59.51%, and that of CD15 and CD11b+ were 43.06% and 22.07%, respectively. 86.39% of AML patients were found to have at least one LAIP, the highest incidence being in AML-M1 and M3 subtypes and the lowest in AML-M4Eo subtype. The cross-lineage antigen and asynchronous antigen expression were the most frequent aberrant phenotypes. CD7, CD19 and CD56 expressing on CD34+ cells were major cross-lineage antigen. For asynchronous antigen expression, CD34+ CD64+, CD117+ CD11b+ , CD34+ CD38(-/dim) and CD34+ HLA-DR(-/dim) were seldom expressed on normal BMMNCs (about 0.01%), and the logarithm difference between AML and NBM was larger than 3.0, being the more sensitive LAIP.
Conclusion: MRD detection by multiparameter flow cytometry can be applied to more than 80% of AML patients.