Involvement of leukotriene B4 in dermatophyte-related itch in mice.

Proteinase-activated receptor-2 (PAR2) is involved in dermatophyte-induced scratching and leukotriene B4 (LTB4) release from keratinocytes. We investigated whether PAR2-mediated LTB4 production is involved in dermatophyte-induced scratching. Dermatophyte extract was injected intradermally and scratching was observed in mice. LTB4 was determined by enzyme immunoassay. Dermatophyte extract-induced scratching was inhibited by zileuton (5-lipoxygenase inhibitor), ONO-4057 (LTB4 antagonist), FSLLRY-NH2 (PAR2 antagonist), and anti-PAR2 antibody. Dermatophyte extract injection increased the cutaneous content of LTB4, which was inhibited by zileuton and FSLLRY-NH2. These results suggest the involvement of LTB4 in dermatophyte-associated itch. LTB4 production might be due to PAR2 stimulation in the skin.