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The effect of prostaglandin D2 on the response of human skin to histamine.

The interaction of prostaglandin D2 (PGD2) and histamine in human skin was studied by intradermal injection of the compounds alone or in combination in healthy volunteers. Responses were recorded by measurement of areas of wheal and erythema, and changes in cutaneous blood flow quantified using a laser Doppler flow meter. The effect of a near-threshold dose of PGD2 on histamine dose-response relationships and on the response to a single low dose of histamine were examined. Histamine caused dose-related increases in blood flow and in areas of wheal and erythema in human skin. Prostaglandin D2 caused dose-related increases in blood flow and erythema area, but not wheal area, in the dose range used. When the compounds were injected together, PGD2 did not potentiate the increase in blood flow and areas of wheal and erythema due to histamine. The modest augmentation of histamine response in the presence of PGD2 could be attributed to summation alone. The role of PGD2 in cutaneous disorders such as the physical urticarias, in which its release has been demonstrated, is therefore uncertain. In the amounts measured in the urticarias, it is unlikely alone to cause a significant cutaneous response; nor does it appear to act by potentiation of the response to histamine.