Phenotypic analysis of T-cell leukemia in Egypt

ABSTRACT

Leukemic cells from 46 T acute lymphoblastic leukemia [ALL] cases and 2 T chronic lymphatic leukemia [CLL], one T prolymphocytic leukemia [PLL] and one T lymphocytic lymphoma in leukemic phase [DLL] were studied with a wide panel of T cell markers. The panel included monoclonal antibodies [Mo Abs] belonging to CD1 [OKT6], CD2 [T11, X11, G144], CD3 [OKT3/Leu4], CD4[OKT4/Leu3a], CD5 [Leu1, T1, A50, L73D9], CD7 [Leu9, I21], CD8 [OKT8/Leu2a]. Other Mo Abs used included OKT9, OKT10, and HNK1. Immunoperoxidase technique using the Avidin-Biotin complex [ABC] method was used for staining. The 46 ALL cases expressed 46 different phenotypes reflecting an extreme degree of heterogeneity. Twelve L1 cases studied showed equal distribution among the 3 intrathymic stages with 4 cases in each group, while 33 L2 cases showed 9 in stage I, 19 in stage II and 5 cases in stage III. The most sensitive CDs in diagnosing T ALL both in children and adult respectively CD5 [100%, and 92.9%], CD7 [92.3% and 81.3%] and CD2 [80.8% and 82.4%]. The most sensitive Mo Ab were Leu1 [81.8%] followed by I21 [71.1%], T11 [70.2%] and Leu9 [68.9%]. The most sensitive combination of 2 Mo Abs was Leu1, I21 [100%] followed by Leu1, T11 [97.4%]. Five of the 46 ALL cases reacted with HNK1 denoting an origin from the natural killer [NK] subset. The PLL cases expressed the helper phenotype. The 2 CLL cases and the DLL case expressed the suppressor phenotype; one of the CLL cases reacted with HNK1. The findings encountered in ALL cases as regards the degree of heterogeneity, distribution according to intrathymic stage of origin in children and adults, sensitivity of various CDs and Mo Abs or prevalence of HNK1 + cases are different from those reported in the western countries; a finding that may reflect a different biological nature of the T ALL