Acute myeloid leukemia (AML) is a clonal malignant disease of the hematopoietic tissue. The diversity of the clinical, the hematological and the genetic features among patients with AML has been recognized. Considerable progresses in defining new diagnostic and prognostic markers have been applied in AML treatment. The detection of specific molecules in the leukemic cells has special relevance and is mandatory for the identification of certain subtypes of myeloid neoplasms (Arber
* CD200 is a trans-membrane cell surface glycoprotein belonging to the type1 immunoglobulin super family (Wright , ). Expression of CD200 is normally seen in some population of T and B-lymphocytes, neurons and endothelial cells (Wright). CD200 induces immunosuppression through engagement with CD200R, a cell-surface receptor homolog, which is expressed on leukocytes of myeloid lineage, including mast-cells, macrophages, basophils, dendritic cells as well as certain T-cell populations. CD200, which is frequently over expressed in AML blasts and is associated with a worse outcome. It has the potential to induce the formation of CD4+ CD25+ FoxP3+ regulatory T cells (Tregs), a subset of immunosuppressive T cells that are linked with a poor prognosis in AML (Coles ). Abstract Background: Acute myeloid leukemia (AML) escape from immunosurveillance by immunosuppression. CD200 and CD56 expression represented an independent prognostic factor in many hematological malignancies but its importance in AML patients remains to be identified. Methods: CD200 and CD56 expression were assessed in the bone marrow blasts for Fifty-two (51) newly diagnosed AML by flowcytometry before start of therapy. Conclusions: CD200 and CD56 positive expression by myeloblasts at diagnosis denote poor prognostic indicator and correlated with poor cytogenetic findings. CD200 could be used as therapeutic target in AML. Keywords: CD200- CD56- AML- Prognosis RESEARCH ARTICLE Clinical Significance of CD200 and CD56 Expression in Patients with Acute Myeloid Leukemia, Leukemic cells express leukemia-associated antigen, MHC, co stimulatory molecules and ligands for natural killer (NK) cells activating receptors, therefore leukemic cells are susceptible to be attacked by T and NK cells (el-Shami ). CD56 antigen, a 200-220 kDa cell surface glycoprotein, identified as an isoform of the neural adhesion molecules (NCAM) (Gattenlöhner ). CD56 firstly described as NK cell and then found in several hematopoietic malignancies including AML (Yoshida ). CD56 was associated with poor prognosis in patients with acute myeloid leukemia (Alegretti ). We herein, study the expression level of CD200 and CD56 in de-novo acute myeloid leukemia patients to estimate the prognostic value of their positive expressions individually in AML cases
