الفهرس 
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Abstract
Acute myeloid leukemia (AML) is a clonal hematopoietic stem cell disorder, characterized by arrested differentiation, inappropriate proliferation and survival of immature myeloid progenitors. The AML has the lowest survival rate of all leukemias, so, assessment of the prognostic factors in AML is very important.
This work aimed to assess CD47 expression in Egyptian patients with AML, to correlate the prognostic value of CD47 expression with other known (clinical and laboratory) prognostic factors.
The current study was carried out on 30 newly-diagnosed AML patients. All patients were subjected to complete history taking, thorough clinical examination and laboratory investigation including: complete blood picture, bone marrow aspiration with examination of Leishman-stained peripheral blood and bone marrow smears, immunophenotyping and detection of the level of CD47 expression by flow cytometry.
Most of the studied AML patients expressed CD47 in high measurable levels. However, when co-expression with CD34 was used, the expression percentage varied. Using the receiver operating characteristic (ROC) curve, a cut-off value for CD47/34 co-expression was identified, allowing the most significant differentiation between AML cases with remission and those who relapsed. This cut-off value was found to be 31.5%.
According to the cut-off value, the 30 studied AML patients fitted into 2 groups. Seven patients (23.3%) had low CD47/CD34 values (below these cut-off level) and 23 patients (76.7%) with high CD47/CD34 values (above the cut-off level). Both groups were subjected to statistical comparison.
There was no significant association between CD47/CD34 co-expression with any of the studied demographic, clinical and laboratory variables except for fever.
However, there was significant negative association between CD47/CD34 co-expression and response to chemotherapy, where patients with increased expression of CD47/CD34 were mostly non-responders to chemotherapy, while most of those with decreased co-expression of CD47/CD34 responded to chemotherapy. So CD47/CD34 could be regarded as an independent prognostic factor for the prediction of poor response to chemotherapy.
Moreover, CD47/CD34 co-expression showed significant association with disease outcome. The AML patients group with high CD47/CD34 co-expression had poorer outcome than the group with low expression. The CD47/CD34 co-expression also showed a statistically significant negative correlation with OST and DFS, which led to a shorter OST and DFS of the ”high group expression” patients.
Finally, the results of the present study confirmed that CD47/CD34 co-expression is an independent prognostic predictor for AML relapse and survival being associated with poor outcome and decreased chemotherapeutic response in AML patients. Additionally, the present data indicated that CD47 surface expression is an important marker in AML which can rapidly and easily be determined by FCM at disease presentation. The CD47/CD34 co-expression, therefore, should be incorporated into the initial laboratory work-up and risk-stratified treatment strategies for all newly diagnosed AML patients.