LOCALIZED HEAT URTICARIA

A case of localized heat urticaria is reported in a 24-year-old Caucasian woman who also suffered from ragweed allergy and dermographism. A series of experimental procedures were performed to study the mechanism by which heat urticaria is produced. It is shown that the reaction was blocked partially by prior infiltration of the skin site with chlorpheniramine and totally by xylocaine or prooaine. Triamcinolone, saline, or glucose solution had no effect. Passive transfer could not be obtained. The patient showed an undue sensitivity to minimal amount of compound 48 80. A skin site rendered totally unresponsive to heat by repeated challenges still gave a 3+ reaction to ragwood. The results of these experiments suggest: (1) The wheal and flare reaction observed after intradermal injection of ragweed differs in its mechanism from the urticarial response induced by local heat challenge. (2) The mediators liberated in each reaction are probably different. (3) The nervous system is involved in some ways in the production of the urticarial response to heat. (4) The heat-induced urticaria in this case might represent an abnormal sensitivity of mediator-containing cells to various stimuli. © 1969.