Pinnal anaphylaxis in the mouse. Mediating antibodies and rhythmic variations in the response.

The anaphylactic reaction in the pinna of a mouse actively sensitized to horse serum is mediated by IgG1 and IgE antibodies. Anaphylactic sensitivity is subject to diurnal variation, peak sensitivity occurring at 16.00 hours and minimum sensitivity at 10.00 hours. Anaphylactic sensitivity also varied with the season of the year, being lower during June and July than in the rest of the year, when the reaction was fairly constant.