title: Biologic allergen assay for in vivo test allergens with an in vitro model of the murine type I reaction.
abstract: BACKGROUND
  The determination of the biologic activity of allergenic extracts in human beings is limited for ethical and practical reasons. The establishment of a simplified in vitro model, which mimics a main event of the type I reaction, should provide true benefit for manufactures, researchers, and clinicians.
  
  
  OBJECTIVE
  This study was designed to develop and evaluate a mediator release assay based on rat bosophil leukemia cells for the purpose of investigating allergenic extracts.
  
  
  METHODS
  Rat basophil leukemia cells were passively sensitized with murine IgE raised against allergens and stimulated by serial dilutions of allergenic extracts in a dose-related manner. The allergen-specific degranulation was monitored by measuring the release of beta-hexosaminidase.
  
  
  RESULTS
  The investigation of standardized commercial allergen products for in vivo diagnostics (birch pollen, cat dander, and bee venom) allowed a quantitative description of differences in biologic activity in accordance with the declared activity units. The Fel d 1 content was determined in 17 cat dander extracts and correlated well with the results of a two-site binding ELISA (r = 0.93, log/log). Extremely low allergen amounts in the range of 10 to 100 pg/ml could be easily detected. Moreover, the cross-reactivity pattern of patients allergic to birch pollen could be reproduced with extracts of hazel, alder, apple, and celery.
  
  
  CONCLUSIONS
  The assay is suitable for supplementing quality control of allergenic extracts and for the determination of biologic activity of final allergen products. As a research tool, it allows the study of IgE cross-linking properties of modified and recombinant allergens at an early stage before they are tested in human beings.
authors.affiliation: Department of Allergology, Paul-Ehrlich Institute, Langen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hoffmann
authors.forename: S
authors.initials: S
authors.lastname: Vieths
authors.forename: D
authors.initials: D
authors.lastname: Haustein
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D001514:Bee Venoms / Q000276:immunology; D001681:Biological Assay / Q000379:methods*; D002415:Cats; D002478:Cells, Cultured; D003429:Cross Reactions / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D011058:Pollen / Q000276:immunology; D051381:Rats; D015203:Reproducibility of Results; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D000485:Allergens; D001514:Bee Venoms; D007074:Immunoglobulin G; D007073:Immunoglobulin E; D001619:beta-N-Acetylhexosaminidases