Phenotypic analysis of T-cell acute lymphoblastic leukemia in Egypt

Leukemic cells from 46 T ALL cases were studied with a wide panel of mAb reacting with T cells using an immunoperoxidase technique. The cases included 15 adults (16 years or over) and 31 children (less than 16 years). The mAb used in the panel were: CD1, (T6), CD2 (T11, X11, D66, clone 2), CD3 (T3/Leu4), CD4, (T4/Leu3a), CD5 (Leu1, T1, A50, I73D9), CD7 (Leu9, I21), CD8 (T8/Leu2a) and HNK1. Based on their reactivity with the mAb panel all cases were assigned to one of the intrathymic differentiation compartments. Among the adults, five cases were assigned to compartment I, six to compartment II and four to compartment III. The pediatric cases included eight in compartment I, eighteen in compartment II and five in compartment III. Fifteen L1 cases studied included four in compartment I, seven in compartment II and four in compartment III; while thirty L2 cases showed nine in compartment I, sixteen in compartment II and five cases in compartment III. The most frequently observed CD groups among T ALL cells were CD5 (100% and 88.9% in children and adults respectively), CD7 (93.1% and 84.6%) and CD2 (76.7% and 76.9%). The most frequently reactive mAb in our series was Leu1 (81.8% followed by I21 (71.1%) and Leu9 (68.9%). The most frequently reactive combination of two mAb was Leu1/I21 (100%) followed by Leu1/T11 (97.4%). Five of the 46 cases reacted with HNK1, suggesting an origin from the natural killer (NK) subset. Our results indicate that in T-cell ALL in Egypt the surface phenotype is similar to that of intermediate or late thymocytes in more than 66% of cases. CD5, CD7 and CD2 were the most frequently detected antigens. Studies of the association between T-cell phenotype and socioeconomic status are warranted.