Melanocyte-Stimulating Properties of Arachidonic Acid Metabolites: Possible Role in Postinflammatory Pigmentation


Yasushi Tomita, M.D., Department of Dermatology, Tohoku University School of Medicine, Sendai 980, Japan.


Normal human epidermal melanocytes became swollen and more dendritic with an increase in the amount of tyrosinase and immunoreactive b-locus protein when they were cultured for 2 days with the following arachidonic acid metabolites: prostaglandin (PG) D2, leukotriene (LT) B4, LTC4, LTD4, LTE4, thromboxane (TX) B2 and 12-hydroxy eicosatetraenoic acid (12-HETE). The effect of LTC4 was particularly strong compared to that of PGE2, about which we have previously reported. On the other hand, PGE1, PGF and 6-ketoPGF did not show any significant stimulatory effect. These data suggest that arachidonate-derived chemical mediators, especially LTC4, may be responsible for the induction of post-inflammatory hyperpigmentation of the skin.