Inhalation challenge in humidifier fever

Abstract

When exposed to an amount of contaminated humidifier water roughly equivalent to that inhaled over an 8-h period at their work place, 4 of 6 subjects developed symptoms of humidifier fever. Two non-exposed subjects failed to react to the same challenge. Characteristic lung function, temperature and leukocyte changes were recorded. A fall in gas transfer previously reported was not seen. That the reaction was immunologically mediated and not due to endotoxin activity was shown by a negative pyrogen response in rabbits inoculated i.v. with concentrated humidifier water. The nature of the immune response does not reside with the ability of humidifier fever antigens to activate complement. Skin testing produced an immediate weal and flare in the 4 subjects with precipitins and may reflect the presence of short-term anaphylactic IgG antibody.