title: Repeated exposure to low levels of sulfur dioxide (SO2) enhances the development of ovalbumin-induced asthmatic reactions in guinea pigs.
abstract: BACKGROUND
  Sulfur dioxide (SO2) is one of the major air pollutants. It is known to aggravate asthma symptoms in human beings, but few studies have focused on the effects of SO2 upon the development of bronchial asthma in animal models.
  
  
  OBJECTIVE
  This study was undertaken to evaluate the role of SO2 upon the development of ovalbumin (OA)-induced asthmatic reactions in guinea pigs.
  
  
  METHODS
  Guinea pigs were divided into four groups: (1) OA- and SO2-exposed group (n = 12), (2) SO2-exposed group (n = 12), (3) OA-exposed group (n = 11), and (4) saline-exposed group (n = 7). Guinea pigs of the first and second groups were exposed to 0.1 ppm SO2 for 5 hours a day on 5 consecutive days. Guinea pigs in the first and third groups inhaled 0.1% OA aerosols for 45 minutes a day on days 3, 4, and 5. One week after the sensitization procedure, all the guinea pigs underwent bronchial challenge with 1.0% OA aerosols, using unrestricted whole-body plethysmography. Bronchoalveolar lavage and histopathologic examination were performed 24 hours after the bronchial challenge.
  
  
  RESULTS
  Increases in enhanced pause (Penh), as an index of airway obstruction, after the bronchial challenge was significantly higher in OA- and SO2-exposed group (group 1) than the other groups (P < .05, respectively). Eosinophil counts in bronchoalveolar lavage fluids were also significantly higher in group 1 than in the other groups (P < .05, respectively). Histopathologic findings of bronchial and lung tissue in the group 1 showed an infiltration of inflammatory cells, bronchiolar epithelial damage, and mucus and cell plug in the lumen, but no significant abnormalities were observed in the other groups.
  
  
  CONCLUSIONS
  These results indicate that repeated exposure to low levels of sulfur dioxide may enhance the development of ovalbumin-induced asthmatic reactions in guinea pigs.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Chongno-gu, Korea.
authors.forename: J K
authors.initials: JK
authors.lastname: Park
authors.forename: Y K
authors.initials: YK
authors.lastname: Kim
authors.forename: S R
authors.initials: SR
authors.lastname: Lee
authors.forename: S H
authors.initials: SH
authors.lastname: Cho
authors.forename: K U
authors.initials: KU
authors.lastname: Min
authors.forename: Y Y
authors.initials: YY
authors.lastname: Kim
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects*; D000818:Animals; D001249:Asthma / Q000139:chemically induced / Q000453:epidemiology* / Q000503:physiopathology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D004781:Environmental Exposure / Q000032:analysis*; D004804:Eosinophils / Q000166:cytology; D006168:Guinea Pigs; D007958:Leukocyte Count; D008297:Male; D010047:Ovalbumin; D015995:Prevalence; D012720:Severity of Illness Index; D013458:Sulfur Dioxide / Q000009:adverse effects*
chemical_list: D000393:Air Pollutants; D013458:Sulfur Dioxide; D010047:Ovalbumin