Sunburn Effect on Keratinosomes

Abstract

Moderate sunburn in normal whites produced a statistically significant decrease in keratinosomes in epidermal cells of the upper malpighian and the granular layer as early as two hours postirradiation. This decrease persisted up to 72 hours. At 120 hours, keratinosomes were visible again in normal numbers. Keratinosomal disappearance preceded cytoplasmic degeneration in other compartments of keratinocytes of the upper epidermis by three hours and was thus the first morphologically visible sign of epidermal cell injury after ultraviolet (UV) irradiation. It is suggested that the disappearance of keratinosomes was involved in producing further cytoplasmic alterations of epidermal cells and that keratinosomal disintegration was one of the factors in the pathogenesis of sunburn. The behavior of keratinosomes after UV injury reported here suggests that these organelles, although unique in many ways, have several features in common with lysosomes.