Flowcytometric Immunophenotypic Characterization of Acute Myeloid Leukemia (AML) in Sudan

Abstract

Introduction: Acute Myeloid Leukaemia (AML) accounts for approximately 20% of acute leukemia in children and 80% of acute leukemia in adults. Immunophenotyping has become extremely important not only in diagnosis and subclassification of AML but also in the detection of the minimal residual disease. Immunophynotypic pattern of AML in Sudanese patients have not been addressed before. This study was conducted to characterize immunophenotypic patterns of AML in Sudanese patients. Multiparameter flow cytometry and CD45/SSC gating were used to analyze the surface and cytoplasmic antigen expressions in 106 cases of AML during the period mid2010 to mid2011 at Radioisotope Centre Khartoum (RICK). The following antigens: CD45, HLA-DR, CD34, CD117, CD13, CD33, CD19, CD7, cytoplasmic markers (CD3, CD79a, MPO), CD11c, CD14, CD64, CD42a, CD41 and CD61 were used. Results: Almost all AML blasts were expressing CD45 with no significant differences between the subtypes. CD34 have different expressions in AML subtypes. CD13 and CD33 were also studied among the blast population having mean positivity of 51.5% and 49.8% respectively in all AML subtypes collectively. CD33 was found to have higher positivity among AML-M4 and AML-M5 with mean positivity of 75.9% and 76.6% respectively. CD13 and CD33 had no correlation for all AML subtypes except for AML-M5 with very strong negative correlation(r=-0.913). Apparent expression of CD7 and CD19 were expressed in 45.1% and 13.6% of all cases respectively. CD7 was mostly expressed in AML-M2 and AML-M3 (75%) and least in AML-M5, while CD19 was only expressed in cases of AML-M0 and AML-M7. Conclusion: Flowcytometric analysis of acute leukemia by combining the patterns and intensity of antigen expression improved the diagnosis of AML in our centre. Immunophenotyping results and FAB classification of our AML patients were comparable to international published studies.