The Role of Apoptosis Regulating Genes BcL-XL and BcL-XS in Acute Lymphoblastic Leukemia

This study included 30 ALL cases of which 19 (70.4%) were B-ALL, 8 (29.6%) were T-ALL cases and 3 bilineage ALL cases. Sixteen cases were BcL-XL positive, (59.3%) compared to none of the control group, a difference that was statistically highly significant (/? 0.001). We had one case of T-ALL that was BcL-XS positive compared to none in the control group. During the 4 year follow up period we had 3 relapses all of them strongly expressed BcL-XL but non expressed BcL-XS. At the end of this study our results support the hypothesis of implication of BcL-XL in the pathogenesis of ALL, being more expressed in ALL cases than in normal counterparts, and that increased expression of BcL-XL in blast cells is accompanied with increased incidence of relapse which means increased resistance to chemotherapy. Elucidation of the relationship between the anti-apoptosis and antiproliferation activities of BcL-XL and BcL-XS could have therapeutic implications as well as prognostic significance.