الفهرس 
ACUTE LYMPHOBLASTIC LEUKEMIAOnly 14 pages are availabe for public view
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Abstract
A
cute lymphoblastic leukemia (ALL) is a malignant disorder of lymphoid progenitor cells that proliferate and replace the normal hematopoietic cells of the bone marrow. These lymphoblasts replacing the normal bone marrow elements result in a marked decrease in the production of normal blood cells.
There are many prognostic factors in ALL such as age, sex, race, leukemic burden, laboratory criteria (initial TLC, hemoglobin level, platelet count and serum immunoglobulins), immunophenotyping, chromosomal abnormalities, duration to induction of remission, drug resistance profiles, and minimal residual disease. Assessment of these factors is mandatory for therapeutic assignment.
CD44 is the cell adhesion molecule involved in a variety of important biological events such as embryogenesis, hematopoiesis, lymphocyte homing, lymphocyte activation, inflammatory reactions, and tumor dissemination. It represents a large protein family, which includes the standard form or a form with a molecular mass of 85-90 kDa, and a multiplicity of isoforms generated by alternative splicing of transcripts and subsequent variable glycosylation. These high Molecular mass variants are rarely expressed on normal cells but frequently expressed on leukemic cells.
The present study aimed to assess CD44 expression in pediatric and adults patients with ALL, and to evaluate its association with the different demographic, clinical and laboratory data, as well as its relation to disease outcome.
The current study was carried out on 48 newly diagnosed childhood and adults ALL patients. All patients were subjected to the following:
• Complete history taking and clinical examination
• Laboratory investigations including:
1. Complete blood picture (CBC).
2. Peripheral blood smears
3. Bone marrow aspiration and examination of Leishman-stained bone marrow smears.
4. Karyotyping by G-banding.
5. Immunophenotyping using the routine panel in addition to assessment of the level of CD44 expression by flow cytometry.
In this work, 62.7% ALL patients positively expressed CD44. On analyzing the relationship of CD44 expression with various studied standard prognostic factors, no significant association was detected between it and any of those factors except for initial TLC and CNS infiltration. On the other hand No significant association was detected between CD44 expression and any of lymphadenopathy or hepatosplenomegaly.
Regarding the karyotypic pattern of CD44 +ve patients, it was found to be significantly associated with unfavorable structural karyotyping mostly in the form of 11q23 (MLL) rearrangement.
The present study showed that a significant positive association was detected between unfavorable outcome (incomplete remission, relapse and death) and positive CD44 expression. In addition, patients with positive CD44 expression had a shorter DFS and OST compared with negative patients.
The association between the high +ve CD44 expression with poor clinical outcome may explained by that; CD44 overexpresses on hematopoietic cells and has been implicated in the interactions between bone marrow stromal layers and hematopoietic progenitors.
In conclusion, CD44 protein expression may serve as a powerful prognostic marker in childhood and adulthood ALL. Its high expression may identify subgroup of ALL patients as high risk group; require assignment of intensified therapeutic protocol assisting to improve the outcome. That analysis of its expression may contribute to improve the management of ALL patients who lack prognostic cytogenetics.