ABSTRACT
Early wheal responses to intracutaneous codeine injection have virtually no tendency to proceed to late cutaneous responses in normal subjects and patients with chronic urticaria. This finding is taken to indicate that the transient burst of mast cell mediator release/activation in a quantity sufficient to elicit a sizable early response may not, by itself, fulfill conditions required to lead to late cutaneous allergic responses. In patients with angioedema and a recent requirement for steroid therapy early wheals followed by small late cutaneous responses were elicited by codeine and histamine. This effect by histamine, not observed in normals, indicates a unique host susceptibility to prolonged responses in these individuals. The inhibition of these small late responses by ingested prednisone may be representative of the mechanism of therapeutic efficacy of the drug in these cases.
