Rat model of passive lung anaphylaxis induced by trichosanthin

Rats were sensitized by sc injection of 0.25 mg trichosanthin, a protein extracted from Radix Trichosanthin, and an adjuvant Al(OH)3 gel into each paw. This was followed by ip injection of pertussis vaccine(1* 10(9)) dead pertussis bacilli). High titre antisera containing heatlabile antibody were obtained from the rats on d 10 after sensitization. Rats weighing 265+/- 43 g were passively sensitized by iv injection of the high titre antisera 0.5-2.5 mL/kg and the challenged with trichosanthin in 24-96 h. The airway resistance measured by lung-overflow technique was increased. Owing to anaphylactic bronchoconstriction, the degree of rat passive lung anaphylaxis was closely related to antisera titre, dosage of antisera as well as the challenging dose of the antigen. Three types of anti-asthmatic drugs(isoprenaline, disodium cromoglycate and aminophylline) prevented the increase of lung overflow. It appears that this is a useful and simple model for screening anti-asthmatic drugs.