title: Differentiation of human keratinocytes is associated with a progressive loss of interferon gamma-induced intercellular adhesion molecule-1 expression.
abstract: Intercellular adhesion molecule-1 (ICAM-1) expression is a necessary requirement for leucocyte/keratinocyte interactions, and keratinocyte upregulation of ICAM-1 is seen in several inflammatory dermatoses. While keratinocytes have a very low constitutive expression of ICAM-1, they can be induced to upregulate ICAM-1 in response to several inflammatory cytokines, such as interferon-gamma (IFN gamma). There is some evidence to suggest that the state of keratinocyte differentiation may influence the level of ICAM-1 expression induced by IFN gamma. The purpose of this study was to investigate the hypothesis that keratinocytes, as they differentiate, may lose their ability to increase their expression of ICAM-1 in response to IFN gamma. Keratinocytes from 13 donors were cultured under conditions which either permitted (Green's medium) or inhibited (MCDB153) differentiation. The ICAM-1 expression in response to IFN gamma was assessed by a sensitive, cell-based, ELISA, and related to the state of differentiation of the cells (as assessed by a quantitative assay for involucrin). While keratinocytes grown in MCDB153 remained responsive to IFN gamma throughout 4 days of culture, the response of keratinocytes grown in Green's medium progressively decreased, so that, by day 3, only a high concentration of IFN gamma (500 U/ml) led to a significant increase in ICAM-1 expression. After 4 days in culture, no upregulation of ICAM-1 was seen. The deterioration in the response of Green's-cultured keratinocytes to IFN gamma mirrored an increase in their expression of involucrin in parallel cultures. Overall, our data demonstrate a progressive loss in the ability of keratinocytes to upregulate ICAM-1 in response to IFN gamma, which is associated with differentiation of these cells. This would support the view that only basal proliferative keratinocytes are responsive to inflammatory cytokines, and play a part in the initiation and amplification of inflammatory reactions in vivo.
authors.affiliation: University Department of Medicine, Northern General Hospital, Sheffield, U.K.
authors.forename: M C
authors.initials: MC
authors.lastname: Little
authors.forename: D J
authors.initials: DJ
authors.lastname: Gawkrodger
authors.forename: S
authors.initials: S
authors.lastname: Mac Neil
mesh_terms: D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D007371:Interferon-gamma / Q000276:immunology*; D015603:Keratinocytes / Q000166:cytology / Q000276:immunology*; D011994:Recombinant Proteins; D015854:Up-Regulation
chemical_list: D011994:Recombinant Proteins; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma