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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 microgram/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 24 h 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 24 h. The pro-inflammatory agents neither potentiated nor prolonged the duration of the hyperresponsiveness.