Formaldehyde exposure enhances inhalative allergic sensitization in the guinea pig

Formaldehyde (FA), a common indoor air pollutant, has been associated with increased prevalence rates of asthmatic symptoms among exposed individuals in epidemiologic surveys. We studied the influence of FA exposure on inhalative allergic sensitization in the guinea pig. Three groups of guinea pigs (n= 12 each) were exposed to clean air or two different FA concentrations (0.13 and 0.25 ppm) over 5 consecutive days. Exposure was followed by inhalation of 0.5% ovalbumin (OA) as sensitizing allergen. Three weeks later, specific bronchial provocation with OA was performed with body plethysmographic measurement of compressed air (CA). Furthermore, specific anti‐OA‐IgGI (reaginic) antibodies were determined in serum. In a further six animals, the respiratory tract was examined histologically for signs of inflammation directly after the end of FA or clean air exposure. In the group exposed to 0.25 ppm FA, 10/12 animals were found to be sensitized to OA (positive reaction on specific provocation) vs. 3/12 animals in the control group (P