title: Ultrastructure of vascular permeability in urticaria.
abstract: BACKGROUND
  Few studies have addressed the ultrastructure of vascular permeability in urticaria.
  
  
  OBJECTIVE
  To describe the types of endothelial cell organelles involved in vascular permeability in drug-induced acute urticaria (DIAU).
  
  
  METHODS
  Seven patients with DIAU were enrolled in the study. Biopsies of urticarial lesions and apparently normal skin were performed. The 14 collected fragmentswere processed with immunogold electron microscopy using single stains for tryptase and factor XIIIa (FXIIIa) and double immunogold labeling for both tryptase and FXIIIa.
  
  
  RESULTS
  Some sections demonstrated mast cells in the degranulation process, in both anaphylactic and piecemeal degranulation. After double immunogold staining, 10 nm (FXIIIa) and 15 nm (tryptase) gold particles wereboth present, covering the granules in the mast cells, indicating that both tryptase and FXIIIa were localized within the granules of these cells. Interestingly, we found strong evidence of the presence of caveolae and vesico-vacuolar organelles (VVOs) in the endothelial cells of the biopsies. In addition to these findings, we were able to demonstrate the presence of tryptase and FXIIIa in the endothelial celIs, in urticarial lesions and in apparently normal skin.
  
  
  CONCLUSIONS
  VVOs are present in the endothelial cells of post-capillary venules in DIAU. This is the first report on the expression of FXIIIa and tryptase in the cytoplasm of endothelial cells in urticaria.
authors.affiliation: Department of Dermatology, School of Medicine, Sao Paulo University (FMUSP), Sao Paulo, Brazil. prcriado@uol.com.br
authors.forename: Paulo R
authors.initials: PR
authors.lastname: Criado
authors.forename: Roberta F J
authors.initials: RF
authors.lastname: Criado
authors.forename: Cleusa F H
authors.initials: CF
authors.lastname: Takakura
authors.forename: Carla
authors.initials: C
authors.lastname: Pagliari
authors.forename: Jozélio F
authors.initials: JF
authors.lastname: de Carvalho
authors.forename: Mirian N
authors.initials: MN
authors.lastname: Sotto
authors.forename: Cidia
authors.initials: C
authors.lastname: Vasconcellos
mesh_terms: D000208:Acute Disease; D000328:Adult; D002199:Capillary Permeability; D002648:Child; D003593:Cytoplasm / Q000378:metabolism / Q000648:ultrastructure; D004342:Drug Hypersensitivity / Q000209:etiology / Q000276:immunology*; D042783:Endothelial Cells / Q000378:metabolism / Q000648:ultrastructure; D026122:Factor XIIIa / Q000378:metabolism; D005260:Female; D006801:Humans; D008854:Microscopy, Electron; D008875:Middle Aged; D015388:Organelles / Q000378:metabolism / Q000648:ultrastructure; D013194:Staining and Labeling; D053802:Tryptases / Q000378:metabolism; D014581:Urticaria / Q000139:chemically induced* / Q000276:immunology
chemical_list: D026122:Factor XIIIa; D053802:Tryptases