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

Area of Science:

• Immunology
• Physiology

Background:

• Systemic anaphylaxis is a severe allergic reaction.
• Immunoglobulin E (IgE) is the primary antibody class involved in immediate hypersensitivity reactions.

Purpose of the Study:

• To characterize the physiological effects of systemic anaphylaxis induced by horseradish peroxidase (HRP) in rabbits producing only IgE antibodies.
• To investigate the response to a secondary antigen challenge after initial recovery.

Main Methods:

• Anesthetized rabbits producing anti-HRP IgE antibodies were challenged with HRP.
• Ventilatory, lung mechanical, and cardiovascular parameters were monitored.
• Histological examination of lung tissue was performed.
• Circulating basophil levels were assessed before and after reactions.

Main Results:

• HRP challenge induced significant changes in breathing frequency, lung compliance, pulmonary resistance, and cardiovascular parameters (pulmonary hypertension, systemic hypotension).
• Physiological recovery occurred within 60 minutes.
• A second HRP challenge elicited a similar reaction, though lung mechanics were less affected.
• No pulmonary edema or vascular plugging was observed histologically.
• The first reaction depleted circulating basophils, but the second reaction occurred without them.

Conclusions:

• Horseradish peroxidase-induced anaphylaxis in IgE-producing rabbits causes distinct ventilatory, respiratory, and cardiovascular alterations.
• Repeated antigen challenge can elicit a similar anaphylactic response, even in the absence of circulating basophils.
• These findings further elucidate the role of IgE in systemic anaphylaxis and antigen challenge responses.