Acute hypersensitivity to aerosolized histamine induced by aerosolized ovalbumin in guinea pigs

Abstract

Acute airway hyperresponsiveness can be induced after exposure to aerosolized ovalbumin in sensitized guinea pigs. The purpose of the present studies was to determine if “pro-inflammatory agents” would potentiate and prolong antigen-induced pulmonary hyperresponsiveness to histamine in guinea pigs. Guinea pigs were sensitized to aerosolized ovalbumin by exposing them to a 3 min aerosol, generated ultrasonically from a 10% ovalbumin solution on day 0 and day 7. On day 13 the guinea pigs were exposed to a 3 min aerosol of deionized water or a pro-inflammatory agent (1 μg/ml PAF, 1 mg/ml LPS, or 4%B. pertussis vaccine). Twenty-four hours later, on day 14, the conscious guinea pigs were challenged with a 3 min aerosolized ovalbumin exposure (under isoproterenol cover) and the individual guinea pig responsiveness to aerosolized histamine was determined 2 and 24h later in an anesthetized modified Konzett-Rossler preparation. Under these experimental conditions, ovalbumin challenge to sensitized guinea pigs produced only an acute hyperresponsiveness (about a 3–10-fold shift) to aerosolized histamine, which lasted less than 24h. The pro-inflammatory agents neither potentiated nor prolonged the duration of the hyperresponsiveness.