Increased urine histamine after challenge of contact sensitivity in the mouse.

The urinary excretion of histamine was observed daily during the development of contact sensitivity to picryl chloride in the mouse. After challenge, effected by painting the ears, urine histamine increased about four fold, while the histamine content in the ears did not change significantly. It is suggested that during challenge there is a general release of histamine, which may be the result either of an immediate hypersensitivity reaction or an effect of anaphylatoxin formation after complement activation.