title: Augmented Induction of CD4+CD25+ Treg using monoclonal antibodies to CD200R.
abstract: BACKGROUND
  CD200 is a transmembrane protein delivering immunoregulatory signals after engagement of CD200R. A family of CD200Rs exist (CD200R1-4) with different tissue expression and functional activity. In the presence of anti-CD200R2/3 monoclonal antibodies (mAbs), bone-marrow cells cultured in the presence of (interleukin [IL]-4+granulocyte-macrophage colony-stimulating factor) differentiate into dendritic cells (DCs), which induce CD4+CD25+ Treg. The effect of these mAbs on Treg induced in anti-CD3 activated thymocyte cultures is unknown.
  
  
  METHODS
  BL/6 bone-marrow cells were cultured with GMC-SF and IL-4 in the presence/absence of anti-CD200Rs to generate DCs that induced Treg in C3H lymph-node T cells. Treg were also induced in anti-CD3/CD28-activated C3H thymocytes. Treg activity was assayed by (1) suppression of mixed leukocyte culture (MLC) in cultures using C3H stimulator spleen cells and BL/6 stimulator cells, and (2) by expression of the transcription factor, Foxp3.
  
  
  RESULTS
  Addition of anti-CD200R2/3 mAbs (but not anti-CD200R1) to bone-marrow cultures led to generation of DCs that induced a CD4+CD25+ (Treg) population inhibiting MLCs (C3H cells stimulated with C57BL/6 cells) in a cytotoxic T-lymphocyte-associated antigen (CTLA)-4 and transforming growth factor (TGF)-beta-dependent manner. Anti-CD200R2, but not anti-R1/R3, augmented induction of Foxp3-expressing Treg from anti-CD3/CD28 activated thymocytes. Suppression in MLCs by anti-CD200R1 mAbs was dependent on IL-10 and TGF-beta.
  
  
  CONCLUSIONS
  Unlike anti-CD200R1, anti-CD200R2 both promotes development of DCs with capacity to induce Treg and directly augments thymocyte production of Treg.
authors.affiliation: The Toronto Hospital, University Health Network, and Department of Surgery, University of Toronto, Canada. reg.gorczynski@utoronto.ca
authors.forename: Reginald M
authors.initials: RM
authors.lastname: Gorczynski
authors.forename: Lydia
authors.initials: L
authors.lastname: Lee
authors.forename: Ivo
authors.initials: I
authors.lastname: Boudakov
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics; D003713:Dendritic Cells / Q000276:immunology; D051858:Forkhead Transcription Factors; D007959:Lymphocyte Culture Test, Mixed; D008214:Lymphocytes / Q000276:immunology; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D015375:Receptors, Interleukin-2 / Q000097:blood*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000911:Antibodies, Monoclonal; C492346:CD200 receptor, mouse; D017931:DNA Primers; D004268:DNA-Binding Proteins; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D008562:Membrane Glycoproteins; D015375:Receptors, Interleukin-2