IGE-INDUCED RESPIRATORY AND CIRCULATORY CHANGES DURING SYSTEMIC-ANAPHYLAXIS IN RABBIT

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Abstract
Systemic anaphylaxis was studied after its induction by the administration of 200 .mu.g of horseradish peroxidase into 11 anesthetized rabbits known to be producing anti-horseradish peroxidase antibodies of only the IgE [immunoglobulin E] class. Ventilatory changes included a transient, abrupt decrease in breathing frequency followed by increased minute ventilation. Lung mechanical changes included decreased dynamic lung compliance and increased total pulmonary resistance. Cardiovascular changes included pulmonary hypertension, systemic hypotension and, frequently, a transient bradycardia. Recovery from these physiologic changes took place within 60 min. After recovery, the administration of 2 mg of horseradish peroxidase into 6 of the rabbits induced a 2nd reaction indistinguishable from the first with respect to ventilatory and circulatory alterations; lung mechanical changes were less prominent. No histologic evidence of pulmonary edema or intraluminal plugging of the pulmonary circulation was observed by light microscopy. Although the 1st anaphylactic reaction was accompanied by disappearance of stainable basophils from the circulating blood, the 2nd reaction occurred despite the absence of circulating basophils. These studies further characterize the effects of antigen challenge in rabbits producing detectable concentrations of IgE, but not other classes of antibody to the antigen.