Biochemical, cytological, and immunological mechanisms of rhododendrol-induced leukoderma.
Recently, an unexpected outbreak of patients with leukoderma occurred in Japan with the use of brightening/lightening cosmetics containing rhododendrol (RD). Patients developed leukoderma mostly on the skin sites repeatedly applied with RD, but some patients also had vitiligo-like lesions on the non-applied sites. RD is a tyrosinase-competitive inhibiting substance, thereby serving as an inhibitor of melanin synthesis. Upon inhibition of tyrosinase, RD is converted to new products such as tyrosinase-catalyzed hydroxyl-metabolite, which damage melanocytes. The melanocyte cell lysates seem to induce T-cell response. The frequencies of CD8+ T cells in both lesional skin and peripheral blood are significantly higher in the RD leukoderma as well as non-segmental vitiligo patients than in normal controls. In HLA-A*02:01 positive cases, circulating Melan-A-specific cytotoxic T cells can be detected at a high frequency. It is thus suggested that RD-induced leukoderma is induced by not only cytolysis of melanocytes but also subsequent immune reactions toward melanocytes.
Department of Dermatology, Hamamatsu University School of Medicine, Japan. Electronic address: tokura@hama-med.ac.jp.
Yoshiki
Y
Tokura
Department of Dermatology, Hamamatsu University School of Medicine, Japan.
Toshiharu
T
Fujiyama
Department of Dermatology, Hamamatsu University School of Medicine, Japan.
Shigeki
S
Ikeya
Department of Dermatology, Hamamatsu University School of Medicine, Japan.
Kazuki
K
Tatsuno
Department of Dermatology, Hamamatsu University School of Medicine, Japan.
Masahiro
M
Aoshima
Department of Dermatology, Hamamatsu University School of Medicine, Japan.
Akira
A
Kasuya
Department of Dermatology, Hamamatsu University School of Medicine, Japan.
Taisuke
T
Ito
D000440:Butanols / Q000009:adverse effects* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes; D003358:Cosmetics / Q000009:adverse effects; D006801:Humans; D017496:Hypopigmentation / Q000139:chemically induced* / Q000201:enzymology / Q000276:immunology; D008544:Melanocytes / Q000187:drug effects / Q000276:immunology; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors*
D000440:Butanols; D003358:Cosmetics; C115945:rhododendrol; D014442:Monophenol Monooxygenase
Leukoderma; Rhododendrol; Tyrosinase