Experimental pruritus evoked by platelet activating factor (PAF-acether) in human skin

Cutaneous pruritic effects of synthetic platelet activating factor (PAF-acether) and, in particular, its interference with dermal mast cells, were studied in human volunteers. Intradermal injections of 10-100 ng produced dose-dependent flare and itching responses. The cutaneous reactions were inhibited by local administration of the H1 antihistamine mepyramin. The cutaneous responses were also markedly reduced in histamine-depleted skin. These findings indicate that the cutaneous responses produced by PAF-acether were mediated via an indirect and mainly histamine-dependent mechanism.