ZAP 70 EXPRESSION IN BONE MARROW BIOPSY OF CHRONIC LYMPHOCYTIC LEUKEMIA AMONG IRAQI PEOPLE.

Background:Chronic lymphocytic leukemia (CLL) is a chronic B-lineage lymphoproliferativedisorder characterized byspecific morphological and immunophinotyping features.Ithas a variable clinical course and several biological markers which were used to assess the disease activity and prognosis. Objective:This was designed to determine the frequency of Immunohistochemical expression of CD5 and ZAP 70 (zeta associated protein of 70 kDa)in bone marrow biopsy of CLL patients and detect the significance of ZAP 70 immunohistochemical expression in bone marrow biopsy as prognostic factor . Patients and methods: This retrospective cross-sectional studyis conducted on fortyformalin fixed paraffin embedded blocks of chronic lymphocytic leukemia cases collected from teaching laboratories of medical city in Baghdad along with ten control cases of normal bone marrow during October 2010through April 2011.The sections of bone marrow biopsies were processed routinely with immunohistochemical stainfor CD 5 and ZAP 70 and examined by light microscope. Results: Main clinical findings of CLL cases were lymphadenopathy, splenomegaly, hepatomegaly, weight loss and fever respectively while asymptomatic cases constitute only 10 % of the cases. Main laboratory findings were leukocytosis , absolute lymphocytosis,anemia and thrombocytopenia. Most of these cases were within the high risk group by use modified Rai staging system .CD 5 expressions was found in all cases. So, there is no statistical significant association with disease activity or prognosis, while ZAP 70 expressed in 48 % of study cases and our study revealed that there was a statistical significant association between ZAP 70 expression and the clinical stage of the disease using Modified Rai system .Moreover, there was a statistical significant inverse association between ZAP 70 expression with PCV % and platelet count. Whereas no statistical significantassociation between ZAP 70 expression and white blood cell count , lymphocyte % in the Bone Marrow and peripheral blood or bone marrow involvement by lymphocytes . Conclusions: This study revealed that CD 5 is expressed nearly in all cases of CLL and gives information that this disease is mostly a B cell linage neoplasm and carry?s no significance with disease progression, ZAP 70 is considered an important prognostic marker in CLL and closely related to clinical stage of the disease. Therefore it can predict a clinical course in CLL, ZAP 70 positive score is in significant association with advanced stage of CLL and usually with worse outcome and there is no significant association between CD 5 and ZAP 70 expression in CLL cases was noted.