ABSTRACT
This study was purpose to investigate the immunophenotype of leukemia promyelocytes (LP) and its significance through retrospective analysis of LP immunophenotype and data in new diagnosis of patients with acute promyelocytic leukemia (APL). The immunophenotype of leukemia cells in 71 APL patients was analyzed by means of 6 color immunotyping. The results indicated that MPO, CD33 and CD13 were consistently expressed in leukemia cells of all APL cases with highest average percentages (> 88%) of positive cells among all studied markers. CD117 was found to be positive in 50.7%, and its average percentage of positive cells was 52.5%. Leukemia cells in about 10% cases expressed CD15 weakly, and its average percentage of positive cells was 42.5%. CD34 and HLA-DR showed decreased expressions in a small number of cases and were negative in the others. CD2 and CD56 were weakly expressed in nearly 25% APL cases, and the average percentage of positive cells were 39.3% and 42.3%, respectively. Thereby, it is of the opinion that the typical immunophenotype is characterized by MPO(+)CD13(+)CD33(+)CD117(±)CD15(±)CD34(-)HLA-DR(-) in APL. CD2 and CD56 were expressed significantly higher in CD34(+) or HLA-DR(+) group (including CD34(+) HLA-DR(+), CD34(+) HLA-DR(-) and CD34(-)HLA-DR(+)) than in CD34(-) and HLA-DR(-) group. Significant differences were also found in WBC and platelet counts, percentage of peripheral blood leukemic promyelocytes and the expression of CD13 among CD15 < 10%, 10% < CD15 < 20% and CD15 > 20% groups. It is concluded that the APL has a characteristic immunophenotypic profile, flow cytometric immunophenotyping may be considered as a useful tool for rapid recognition of APL and also may be considered to have an important significance for analysing origin of leukemic cells and clinical outcome of patients.