Background: The systemic anaphylaxis reaction comprises various symptoms, including
hypotension, changes in respiration pattern, and hypothermia. Objective: To elucidate the
role of histamine in each of these symptoms, we induced the passive systemic anaphylaxis
reaction in histidine decarboxylase gene knockout (HDC [-/-]) mice, which lack histamine.
Methods: HDC (-/-) mice were generated by knocking out the HDC gene, which codes for the
unique histamine-synthesizing enzyme. Twenty-four hours after the injection of IgE, HDC …