Cholinergic urticaria, passive transfer experiments from human to monkey.

Passive transfer experiments in cholinergic urticaria were carried out from 16 patients to a Macaca cymnologous monkey. Intravenous Evans blue dye was used to demonstrate vascular permeability. The animal was challenged after 24 h first by heating the serum-injected dorsal skin to 45 degrees C and secondly by superinjection of acetylcholine into serum-injected sites, and a control site. Local heat proved insufficient to evoke a response. Seven of 16 serum-injected sites showed positive reaction to acetylcholine, control injection of acetylcholine did not. These experiments suggest the presence of a serum factor in cholinergic urticaria which, with acetylcholine, causes increased vascular permeability.