title: Acute airway effects of airborne formaldehyde in sensitized and non-sensitized mice housed in a dry or humid environment.
abstract: We investigated the role of air humidity and allergic sensitization on the acute airway response to inhaled formaldehyde (FA) vapor. Mice were sensitized to the immunogen ovalbumin (OVA) by three intraperitoneal injections followed by two aerosol challenges, giving rise to allergic airway inflammation. Control mice were sham sensitized by saline injections and challenged by saline aerosols. Once sensitized, the mice were housed at high (85-89%) or low (<10%) relative humidity, respectively for 48h prior to a 60-min exposure to either 0.4, 1.8 or about 5ppm FA. Before, during and after exposure, breathing parameters were monitored. These included the specific markers of nose and lung irritations as well as the expiratory flow rate, the latter being a marker of airflow limitation. The sensory irritation response in the upper airways was not affected by allergic inflammation or changes in humidity. At high relative humidity, the OVA-sensitized mice had a decreased expiratory airflow rate compared to the saline control mice after exposure to approximately 5ppm FA. This is in accordance with the observations that asthmatics are more sensitive than non-asthmatics to higher concentrations of airway irritants including FA. In the dry environment, the opposite trend was seen; here, the saline control mice had a significantly decreased expiratory airflow rate compared to OVA-sensitized mice when exposed to 1.8 and 4ppm FA. We speculate that increased mucus production in the OVA-sensitized mice has increased the "scrubber effect" in the nose, consequently protecting the conducting and lower airways.
authors: The National Research Centre for the Working Environment, Lersø Parkalle 105, DK-2100 Copenhagen, Denmark. stl@nrcwe.dk
authors: Søren Thor
authors: ST
authors: Larsen
authors: Peder
authors: P
authors: Wolkoff
authors: Maria
authors: M
authors: Hammer
authors: Vivi
authors: V
authors: Kofoed-Sørensen
authors: Per Axel
authors: PA
authors: Clausen
authors: Gunnar Damgård
authors: GD
authors: Nielsen
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D001991:Bronchitis / Q000139:chemically induced* / Q000276:immunology / Q000503:physiopathology; D002645:Chickens; D004781:Environmental Exposure / Q000009:adverse effects*; D005557:Formaldehyde / Q000008:administration & dosage* / Q000633:toxicity*; D006813:Humidity; D019570:Inhalation Exposure / Q000009:adverse effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000633:toxicity; D012123:Pulmonary Ventilation / Q000187:drug effects / Q000502:physiology
chemical_list: D000393:Air Pollutants; D005557:Formaldehyde; D010047:Ovalbumin