Bcl-2 expression in acute myelogenous leukemia: the relation to myeloid antigen expression and response to therapy in...

Product of Bcl-2 gene prolongs survival of hematopoietic cells by inhibition of programmed cell death. The aim of this study is to examine the expression of the bcl-2 protein in a group of patients with AML and its relation to clinical features and response to therapy. Slides from the bone marrow or peripheral blood of 70 patients with AML were assessed for the expression of bcl-2 by immunocytochemistry. The expression of myeloid and non-lineage associated markers was detected by indirect immunofluorescence method. Correlation between bcl-2 and markers expression and patients characteristics was determined. More than 20% positivity for bcl-2 was found in 22 (31.4%) patients. Bcl-2 expression showed an association with M4 and M5 subtypes (p<0.01) and was correlated with clinical parameters including WBC and platelet count, extramedullary disease and Hb level. Bcl-2 expressing cells were significantly higher in CD15(+) and CD13(+) patients and lower in CD11b(+) and CD33(+) cases (p<0.001). Complete remission (CR) rate was significantly lower in cases with 20% or more bcl-2 positivity than others (24.4% v 75.6%). A shorter CR duration was observed in bcl-2+ patients when compared with bcl-2- ones (571+/-50 versus 850+/-17 days)(p=0.0001). The expression of bcl-2 was also associated with shorter survival (p=0.0001). Survival time for bcl-2+ patients was 831+/-44 days versus 1119+/-17 days for bcl-2- ones. CD11b and CD33 positivity was associated with longer survival whereas CD13 and CD15 positivity was correlated with lower survival (p<0.007). In multivariate analysis bcl-2 positivity was associated with poor survival. Bcl-2 expression showed a prognostic value in our patients indicating that even despite of some differences in treatment regimen, immunocytochemical analysis of this marker is still a simple and inexpensive method for evaluation of prognosis in AML patients. Bcl-2 expression may be related to the expression of differentiation associated markers.