The respiratory response of sensitized rats to challenge with antigen aerosols.

An experimental procedure was developed to evaluate the effects of challenging sensitized conscious rats with antigen aerosols. The challenge resulted in changes in the respiratory patterns which were antigen specific and mediated by IgE antibodies. The response was inducible in non-sensitized rats by passive administration of IgE-rich serum. Sprague-Dawley rats were heterogeneous with respect to the respiratory response. A proportion (20--70%) of each group had continuous dyspnoea and other symptoms similar to asthma; the other had only episodes of apnoea. Wistar and Long-Evans rats resembled Sprague-Dawley rats; Fischer 344 rats had apnoea only, even though they produced IgE antibodies. The type of response did not correlate with serum IgE levels. The respiratory responses were reduced by dexamethasone, disodium cromoglycate, epinephrine and theophylline. Rats that respond with dyspnoea may provide a useful experimental model of allergic asthma.