Background: Flow cytometric immunophenotyping is the gold standard, fast and reliable method for diagnosis and subtyping of Acute Lymphoblastic Leukemia.
Objectives: To establish the value of 3-color flow cytometry to assist in diagnosis of Acute Lymphoblastic Leukemia.
Methods: In this study we assessed the immunophenotypic profile of 96 cases of T ALL that presented over a four years using a single laser FACSCalibur flow cytometer. CD45 / Side scatter gating was used to identify the leukemic cells. Antibodies used were to surface and intracellular antigens including CD45, CD1a, CD2, CD3, CD4, CD5, CD7, CD8, CD10,CD13,CD14,CD19,CD20,CD33, CD34,CD38,CD64,CD79a,CD117,HLA-DR,MPO and TdT. Antibodies were conjugated with FITC, PE or PerCP fluorophores.
Results:.
Of the 509 acute lymphoblastic leukemia , 96(18.9%) had T-cell acute lymphoblastic leukemia(T-ALL). Of the 96 ,73(76%) patients were children and 23(24%) were adult. The overall age distribution showed a peak incidence between 10 and 14 with median of 12 years . The male to female ratio was 1.9:1.
Cytoplasmic CD3,CD7 ,CD45 and TdT were expressed in all cases. CD1a was expressed in 29(57.7%) cases out of 53 case. CD5 was expressed in 74(93.7%) out of 79 cases where’s CD2 was expressed in 58(81.7%) out of 71 case. CD4/CD8 were co-expressed in 26(38.3%) cases out of 68 case where’s dual CD4/CD8 negativity were found in 23(33.8%) . CD10 was expressed in 30(35.3%) cases out of 85.
The most aberrant myeloid antigens were CD117 (19.2%),CD13(17.2%) and CD33(9.5%).
Conclusion: T-acute lymphoblastic leukemia is more common among children than adults and males were more effected than females. The proportion of T-ALL to ALL is similar to general distribution pattern in the western countries.
Key Words: Flow cytometry, T- acute lymphoblastic leukemia, Immuno-phenotyping.