IgE induced respiratory and circulatory changes during systemic anaphylaxis in the rabbit

The authors studied systemic anaphylaxis induced by the administration of 200 μg of horseradish peroxidase into 11 anesthetized rabbits known to be producing anti horseradish peroxidase antibodies only of the IgE class. Ventilatory changes included a transient, abrupt decrease in breathing frequency followed by increased minute ventilation; the mechanical changes to the lungs included a decreased dynamic lung compliance and an 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 second reaction inditinguishable from the first with respect to ventilatory and circulatory alterations; however, the mechanical changes to the lungs were less prominent. No histologic evidence of pulmonary edema or intraluminal plugging of the pulmonary circulation was observed by light microscopy. Although the first anaphylactic reaction was accompanied by disappearance of stainable basophils from the circulating blood, the second reaction occurred despite the absence of circulating basophils. These studies characterize further the effects of antigen challenge in rabbits producing detectable concentrations of IgE, but not other classes of antibody to the antigen.