title: Human leukocyte antigen-specific antibodies and gamma-interferon stimulate human microvascular and glomerular endothelial cells to produce complement factor C4.
abstract: BACKGROUND
  The role of the complement system in antibody-mediated rejection has been investigated in relation to circulating complement interacting with renal microvascular endothelium, resulting in the formation of peritubular capillary C4d. However, the possible importance of local complement synthesis is less clear. The aim of this study was to determine whether human vascular endothelium could produce C4 in response to stimulation in vitro.
  
  
  METHODS
  Human microvascular endothelial cells and glomerular endothelial cells were stimulated with endotoxins, cytokines, and human leukocyte antigen-specific antibodies. Synthesis of complement was investigated using western blotting and indirect immunofluorescence. De novo C4 synthesis was confirmed by using C4 small interfering RNA.
  
  
  RESULTS
  Glomerular and microvascular endothelium, both produce C3 and C4 complement protein. Complement synthesis was stimulant-specific-C3 was produced mainly after stimulation with lipopolysaccharide whereas C4 synthesis occurred on treatment with gamma interferon. Culture with human leukocyte antigen-specific antibodies resulted in a significant increase of C4 protein synthesis by both cell lines.
  
  
  CONCLUSIONS
  We have shown for the first time that human microvascular endothelium can be stimulated to synthesize C4 in vitro. The implications of this for clinical transplantation, especially in the context of antibody-mediated rejection, its histological interpretation and as a potential target for therapy would have to be determined by further studies.
authors.affiliation: Renal Unit, University Hospitals Coventry and Warwickshire, Coventry, West Midlands, UK. rizwanhamer@yahoo.co.uk
authors.forename: Rizwan
authors.initials: R
authors.lastname: Hamer
authors.forename: Guerman
authors.initials: G
authors.lastname: Molostvov
authors.forename: David
authors.initials: D
authors.lastname: Lowe
authors.forename: Simon
authors.initials: S
authors.lastname: Satchell
authors.forename: Peter
authors.initials: P
authors.lastname: Mathieson
authors.forename: Rebecca
authors.initials: R
authors.lastname: Ilyas
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Mitchell
authors.forename: For T
authors.initials: FT
authors.lastname: Lam
authors.forename: Habib
authors.initials: H
authors.lastname: Kashi
authors.forename: Lam Chin
authors.initials: LC
authors.lastname: Tan
authors.forename: Chris
authors.initials: C
authors.lastname: Imray
authors.forename: Simon
authors.initials: S
authors.lastname: Fletcher
authors.forename: David
authors.initials: D
authors.lastname: Briggs
authors.forename: Nithya
authors.initials: N
authors.lastname: Krishnan
authors.forename: Robert
authors.initials: R
authors.lastname: Higgins
authors.forename: Daniel
authors.initials: D
authors.lastname: Zehnder
mesh_terms: D000906:Antibodies / Q000187:drug effects / Q000276:immunology*; D000998:Antiviral Agents / Q000494:pharmacology; D015153:Blotting, Western; D002478:Cells, Cultured; D003181:Complement C4 / Q000096:biosynthesis* / Q000187:drug effects / Q000276:immunology; D019084:Fluorescent Antibody Technique, Indirect; D005920:Glomerular Mesangium / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D006084:Graft Rejection / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D016030:Kidney Transplantation / Q000276:immunology / Q000473:pathology
chemical_list: D000906:Antibodies; D000998:Antiviral Agents; D003181:Complement C4; D006680:HLA Antigens; D007371:Interferon-gamma