title: Close association between activated platelets and neutrophils in the active phase of ulcerative colitis in humans.
abstract: BACKGROUND
  Neutrophils are considered to play a causative role in inflammatory mucosal injury in ulcerative colitis (UC), and an association between platelets and neutrophils may contribute to the progression of the inflammatory processes. To test this hypothesis, we performed immunohistochemical and flow cytometric analyses on tissue and blood samples from patients with UC.
  
  
  METHODS
  Colonic mucosal tissues of patients with active (n = 27) or inactive (n = 16) UC and normal controls (n = 11) were subjected to immunohistochemical staining for markers of activated platelets (glycoprotein IIb/IIIa and P-selectin) and neutrophils (neutrophil elastase, myeloperoxidase, and CD66b). The amounts of stained cells were evaluated by computer-aided morphometry. Peripheral blood samples from patients (n = 8) and healthy volunteers (n = 8) were subjected to comparative flow cytometric analysis of activated platelets.
  
  
  RESULTS
  P-selectin-positive activated platelets were frequently aggregated in the inflamed mucosa, especially in ulcerative lesions, and were close to regions of dense neutrophil infiltration. An increase in the number of activated platelets in the colonic lesions was associated with an increase in infiltrating neutrophils and was related to the severity of the disease. The flow cytometric analysis indicated that circulating platelets of patients with UC were highly activated.
  
  
  CONCLUSIONS
  The present study demonstrated that a close association between activated platelets and neutrophils is a prominent pathological change in both the affected colonic mucosa and peripheral blood of patients with active-phase UC. This suggests that platelet-neutrophil association may play an important role in the progression of inflammatory processes in UC.
authors.affiliation: Department of Pathology, Osaka City University Graduate School of Medicine, Osaka, Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Kayo
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ikura
authors.forename: Takehisa
authors.initials: T
authors.lastname: Suekane
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Shirai
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Sugama
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ohsawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Adachi
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Shiro
authors.initials: S
authors.lastname: Nakamura
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Fujiwara
authors.forename: Nobuhide
authors.initials: N
authors.lastname: Oshitani
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Higuchi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Maeda
authors.forename: Kosei
authors.initials: K
authors.lastname: Hirakawa
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Arakawa
authors.forename: Makiko
authors.initials: M
authors.lastname: Ueda
mesh_terms: D000328:Adult; D003093:Colitis, Ulcerative / Q000276:immunology / Q000473:pathology / Q000503:physiopathology*; D003106:Colon / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007413:Intestinal Mucosa / Q000276:immunology / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020556:Neutrophil Infiltration; D019007:P-Selectin / Q000378:metabolism; D015539:Platelet Activation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism
chemical_list: D019007:P-Selectin; D019039:Platelet Glycoprotein GPIIb-IIIa Complex