title: Mouse monoclonal anti-human thrombomodulin antibodies bind to and activate endothelial cells through NF-kappaB activation in vitro.
abstract: OBJECTIVE
  To clarify whether mouse monoclonal antibodies (mAb) against human thrombomodulin (TM), which react with human TM present on the endothelial cell (EC) surface, have anti-endothelial cell antibody (AECA) activity and influence antiinflammatory properties of human TM expressed on the EC surface in vitro.
  
  
  METHODS
  Three preparations of mouse mAb against human TM that react with different sites of the human TM epidermal growth factor-like domain were tested for their ability to 1) bind to ECs, 2) modulate cytokine secretion from ECs, EC adhesion molecule expression, and neutrophil adhesion to ECs, and 3) stimulate nuclear translocation of NF-kappaB through the degradation of cytoplasmic IkappaB in ECs. Recombinant human interleukin-1beta (IL-1beta) was used as a positive control, and mouse IgG1 and mouse IgG2a were used as negative controls.
  
  
  RESULTS
  The 3 preparations of mouse mAb against human TM that bind to unfixed EC monolayers enhanced IL-6 and IL-8 secretion from ECs, up-regulated expression of endothelial leukocyte adhesion molecule 1, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 on EC monolayers, and enhanced neutrophil adhesion to ECs to a degree similar to that observed with IL-1beta stimulation, but they did not induce the secretion of tumor necrosis factor alpha or IL-1beta from ECs throughout the incubation period. The 3 preparations stimulated nuclear translocation of NF-kappaB through the degradation of cytoplasmic IkappaB. Mouse IgG1 and mouse IgG2a did not exhibit such effects.
  
  
  CONCLUSIONS
  These results suggest the possibility that AECA can react with antigens such as TM that are present on the EC surface and activate ECs. Such events on ECs may lead to vascular inflammation and damage in patients with connective tissue diseases and vasculitis in which AECA are present.
authors.affiliation: Jichi Medical School, Tochigi-ken, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okamoto
authors.forename: Seiji
authors.initials: S
authors.lastname: Minota
authors.forename: Taku
authors.initials: T
authors.lastname: Yoshio
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D042783:Endothelial Cells / Q000276:immunology*; D006801:Humans; D051379:Mice; D016328:NF-kappa B / Q000502:physiology*; D018180:Thrombomodulin / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D016328:NF-kappa B; D018180:Thrombomodulin