A STUDY OF THE KINETICS AND PATTERN OF E-SELECTIN, VCAM-1 AND ICAM-1 EXPRESSION IN CHRONIC ACTINIC DERMATITIS

It has been postulated that chronic actinic dermatitis (CAD), an eczem atous photodermatosis, is a type IV hypersensitivity reaction. Express ion of adhesion molecules on dermal blood vessels is critical to the r ecruitment of inflammatory cells into the skin; the pattern and kineti cs of upregulation of these molecules in the skin differ following ult raviolet irradiation and delayed hypersensitivity reactions. We theref ore investigated the kinetics of expression of endothelial leucocyte a dhesion molecules (E-selectin) vascular-cell adhesion molecules 1 (VCA M-1) and intercellular adhesion molecule 1 (ICAM-1) in CAD lesions ind uced by suberythemal solar-stimulated radiation, by immunohistochemica l staining of biopsies taken at 1-168 h after irradiation> In control, unirradiated skin from CAD patients, baseline vessel-associated and i nterstitial ICAM-1, and vessel-associated VCAM-1 were noted; focal ker atinocyte ICAM-1 expression was observed in two of the five patients. Endothelial E-selectin, and vessel-associated and interstitial VCAM-1 expression, were upregulated in induced lesions by 1-5 h in all patien ts, and remained elevated at 120-168 h. Vessel associated, dermal inte rstitial, and keratinocyte ICAM-1 expression was upregulated in all pa tients at 24 h, and remained increased at 120-168 h. These findings di ffer from those observed following ultraviolet irradiation of normal s kin, and resemble those seen in normal skin during a delayed-type hype rsensitivity reaction, supporting the hypothesis that CAD involves a t ype IV response to an as yet unidentified photo-induced antigen.