title: Indoleamine 2,3-dioxygenase and regulatory T cells in acute myeloid leukemia.
abstract: OBJECTIVE
  The microenvironment of acute myeloid leukemia (AML) is suppressive for immune cells. Regulatory T cells (Tregs) have been recognized to play a role in helping leukemic cells to evade immunesurveillance. The mesenchymal stem cells (MSCs) are essential contributors in immunomodulation of the microenvironment as they can promote differentiation of Tregs via the indoleamine 2,3-dioxygenase (IDO) pathway. The aim of the present work was to evaluate the expression of IDO in bone marrow derived MSCs and to study its correlation to percentage of Tregs.
  
  
  METHODS
  Thirty-seven adult bone marrow samples were cultured in appropriate culture medium to isolate MSCs. Successful harvest of MSCs was determined by plastic adherence, morphology, and positive expression of CD271 and CD105; negative expression of CD34 and CD45 using flowcytometry. MSCs were examined for IDO expression by immunocytochemistry using anti-IDO monoclonal antibody. CD4+ CD25+ cells (Tregs) were measured in bone marrow samples by flowcytometry.
  
  
  RESULTS
  MSCs were successfully isolated from 20 of the 37 bone marrow samples cultured. MSCs showed higher expression of IDO and Tregs percentage was higher in AML patients compared to control subjects (P = 0.002 and P < 0.001, respectively). A positive correlation was found between IDO expression and Tregs percentage (P value = 0.012, r = 0.5).
  
  
  CONCLUSIONS
  In this study, we revealed an association between high IDO expression in MSCs and elevated levels of Tregs which could have an important role in the pathogenesis of AML, providing immunosuppressive microenvironment.
authors.affiliation: a Clinical and Chemical Pathology Department, Faculty of Medicine , Cairo University , El Saraya Street, Infront of El Manial Palace, Cairo 11451 , Egypt.
authors.forename: Iman
authors.initials: I
authors.lastname: Mansour
authors.affiliation: a Clinical and Chemical Pathology Department, Faculty of Medicine , Cairo University , El Saraya Street, Infront of El Manial Palace, Cairo 11451 , Egypt.
authors.forename: Rania A
authors.initials: RA
authors.lastname: Zayed
authors.affiliation: a Clinical and Chemical Pathology Department, Faculty of Medicine , Cairo University , El Saraya Street, Infront of El Manial Palace, Cairo 11451 , Egypt.
authors.forename: Fadwa
authors.initials: F
authors.lastname: Said
authors.affiliation: a Clinical and Chemical Pathology Department, Faculty of Medicine , Cairo University , El Saraya Street, Infront of El Manial Palace, Cairo 11451 , Egypt.
authors.forename: Lamyaa Abdel
authors.initials: LA
authors.lastname: Latif
mesh_terms: D000293:Adolescent; D000328:Adult; D002454:Cell Differentiation; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism*; D015470:Leukemia, Myeloid, Acute / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D055815:Young Adult
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase
keywords: 3-dioxygenase; Acute myeloid leukemia; Indoleamine 2; Mesenchymal stem cells; T regulatory cells