Effect of photoaging on skin test response to histamine independent of chronologic age

Abstract

BackgroundSkin prick-puncture test responses to histamine on the upper back and forearms in older individuals are frequently small or absent but are often present or larger when repeated on the lower back. ObjectiveTo determine whether photoaging or natural aging causes a smaller response to a prick-puncture skin test. MethodsPrick-puncture skin tests to histamine were performed on sun-exposed and sun-protected areas in younger (n = 61, aged 20–50 years) and older (n = 63, aged 60–87 years) adult volunteers. The skin was scored for photoaging by physical examination, and coloration was measured by a colorimeter. ResultsLarge variation of photoaging occurred within age groups. Histamine wheals and flare were not different between the 2 age groups, but those adults with the greatest photoaging had smaller histamine wheals and flare on the upper back, with a trend for smaller flares on the volar aspect of the forearms and lower back. There was marked variability in response to histamine within individual adults, depending on the locale of the tests. ConclusionPhotoaging, but not age alone, is associated with a smaller response to histamine in sun-exposed areas. Before prick-puncture skin tests are performed, the skin should be examined for sun damage, and a sun-protected area should be selected; in vitro allergy testing may be substituted if there is no sun-protected skin area.