Evaluation of Bcl 2 and Ki 67 expression in Chronic Lymphocytic Leukemia

Abstract

Background: Chronic lymphocytic leukemia (CLL) is a low-grade B-lineage lymphoid malignancy. Both Ki-67 which is a large nuclear protein associated with cell proliferation and Bcl-2 which is an anti-apoptotic protein which is associated with dysregulation of the intrinsic apoptotic pathway , were thoroughly investigated in many cancer patients particularly in hemopoietic malignancies .Patients, materials and methods: This retrospective study was conducted from November 2009 to May 2010 , on fifty formaline fixed paraffin embedded blocks of CLL cases retrieved from Medical City Teaching Hospital ; their age range was 39-75 years along with twenty control cases with benign reactive marrow , The sections of bone marrow biopsies were processed routinely in Al-Kadimiya teaching hospital laboratory and stained with H&E and the expression of Bcl2 and Ki67 was evaluated by light microscope. Smears stained for Bcl2 were classified according to the scoring system used by Soini Y,et al. ,whereas those stained for ki67 were evaluated by estimation the percentage of positive stained nuclei in the smears as was adopted by Diop S,et al.Results: Immunohistochemical staining of CLL cases revealed that 11/50 cases (22%) were positive for Ki67 showing diffuse or granular nuclear brown stain , whereas all control cases were negative for the marker . Those positive cases significantly correlate with modified Rai system , Hb concentration and platelet count ,but they did not significantly correlate with white blood cell count or lymphocyte % in the bone marrow and peripheral blood smears . Regarding Bcl 2 , 32/50 cases(64%) were positive for the marker showing diffuse cytoplasmic brown reaction ,however no significant correlation was found between Bcl2 score and modified Rai system or with any of the mentioned hematological parameters .Finally , there was no significant correlation between Ki67 and Bcl2 expression .Conclusions: The proliferative marker Ki-67 expression closely related to the clinical stage of CLL patients , thus it could be considered as an informative and simple tool for assessing disease activity . On the other hand ,although Bcl2 expression was high in CLL patients but it did not related with the clinical stage of those patients . Finally . Ki67 and Bcl2 were independent markers and no correlation was found between them as they act on different pathways since ki67 is a proliferative and Bcl2 is an antiapoptotic marker.Keywords : Bcl 2 , Ki 67 , CLL

Keywords

Bcl 2, Ki 67, CLL