title: CTLA4 is expressed on mature dendritic cells derived from human monocytes and influences their maturation and antigen presentation.
abstract: BACKGROUND
  Dendritic cells (DCs) initiate immune responses through their direct interaction with effector cells. However, the mechanism by which DC activity is regulated is not well defined. Previous studies have shown that CTLA4 on T cells regulates DCs function by "cross-talk". We investigated whether there is an intrinsic regulatory mechanism in DCs, with CTLA4 as a candidate regulator.
  
  
  RESULTS
  We confirmed via RT-PCR and flow cytometry the natural expression of CTLA4 on mature DCs derived from human monocytes. Approximately 8% CD1a-positive cells express CTLA4 both on surface and intracellular, whereas 10% CD1a-negative cells express CTLA4 intracellularly, but little expression was observed on the cell surface. The cross-linking of CTLA4 inhibits DCs maturation and antigen presentation in vitro, but does not inhibit endocytosis.
  
  
  CONCLUSIONS
  CTLA4 is expressed by DCs and plays an inhibitory role. CTLA4-expressing DCs may represent a group of regulatory DCs. Because of its wide distribution on different cell types, CTLA4 may play a general role in regulating immune responses.
authors.affiliation: Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China. xiongbiao6@yahoo.com
authors.forename: Xiong B
authors.initials: XB
authors.lastname: Wang
authors.forename: Zhong Z
authors.initials: ZZ
authors.lastname: Fan
authors.forename: Doina
authors.initials: D
authors.lastname: Anton
authors.forename: Annika V
authors.initials: AV
authors.lastname: Vollenhoven
authors.forename: Zhen H
authors.initials: ZH
authors.lastname: Ni
authors.forename: Xiao F
authors.initials: XF
authors.lastname: Chen
authors.forename: Ann K
authors.initials: AK
authors.lastname: Lefvert
mesh_terms: D017951:Antigen Presentation / Q000276:immunology*; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D018949:Antigens, CD1 / Q000276:immunology / Q000378:metabolism; D060908:CTLA-4 Antigen; D002454:Cell Differentiation / Q000276:immunology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D004705:Endocytosis / Q000276:immunology; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007959:Lymphocyte Culture Test, Mixed; D009000:Monocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015703:Antigens, CD; D018949:Antigens, CD1; C419393:CD1a antigen; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human