Reginald M Gorczynski1, Lydia Lee, Ivo Boudakov. 1. The Toronto Hospital, University Health Network, and Department of Surgery, University of Toronto, Canada. reg.gorczynski@utoronto.ca
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.
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.
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