Redistribution of melanosomal complexes within keratinocytes following UV-A irradiation: A possible mechanism for cutaneous darkening in man

Robert M. Lavker*, Kays H. Kaidbey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

In contrast to other ultraviolet (UV) wavelengths, UV-A can induce long-term or "true" pigmentation rapidly with little or no latency. The response cannot be clearly separated from immediated pigment darkening and is too rapid in onset to be explained by neomelanogenesis. In order to investigate possible mechanisms for this phenomenon, UV-irradiated skin was examined microscopically and ultrastructurally 18 h postirradiation. Specimens from skin sites tanned by exposure to melanogenic doses of UV-A showed a paradoxical reduction in the degree of basal melanization by light microscopy compared to unirradiated skin. Ultrastructurally, there was migration and dispersion of packaged melanosomes within keratinocytes from their normal, aggregated location around the nucleus towards the periphery of the cell. These changes were not observed in specimens exposed to melanogenic doses of UV-B. We propose that UV-A wavelengths can selectively cause redistribution of melanin-laden organelles within human keratinocytes in vivo and that this phenomenon accounts for the visually observed hyperpigmentation that develops soon after single exposures to these wavelengths. Dispersion of melanosomal complexes may be another mechanism by which UV-radiation (UVR) can induce tanning in human skin.

Original languageEnglish (US)
Pages (from-to)215-228
Number of pages14
JournalArchives of Dermatological Research
Volume272
Issue number3-4
DOIs
StatePublished - Sep 1 1982

Keywords

  • Immediate pigment darkenin
  • Melanogenesis
  • Tanning
  • UV-A
  • UV-B

ASJC Scopus subject areas

  • Dermatology

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