Background: Keratin 6 (K6) and keratin 10 (K10) are markers for epidermal hyperproliferation and differentiation, respectively, and are both expressed in the suprabasal layers of the epidermis. They may be co-expressed in different stages of the spreading psoriatic lesion, but single expression can also occur. Objective: To investigate to what extent keratinocytes express K6 and K10, and to what extent they co-express K6 and K10 in different stages of the psoriatic lesion. We studied this in spreading psoriatic plaques. Methods: Three 3-mm punch biopsies were obtained from the inner involved margin of a spreading lesion, from the uninvolved skin immediately adjacent to the spreading plaque, and from the distant uninvolved skin of 8 patients with incipient psoriasis. From 9 healthy volunteers, 3-mm punch biopsies were obtained as controls. After preparation of single cell suspensions of these biopsies, a triple staining protocol was performed with markers for K6 (monoclonal antibody LHK6B), K10 (monoclonal antibody RKSE60) and DNA content (TO-PRO-3 iodide). Subsequently, cells were measured with a flow cytometer and the proportion of the markers was calculated using specific software. Results: We observed a population of K6/K10-co-expressing cells, but also populations expressing only K6. These subpopulations varied with the involvement of the lesion. There was a statistically significant difference between the inner margin and the outer margin with respect to the proportion of K6- and K10-expressing cells, whereas more K6-positive and K10-negative cells were detected in the inner margin of the lesions. The proportion of K6/K10-co-expressing cells in the inner margin was significantly different from the distant uninvolved skin. Conclusion: We confirmed that individual keratinocytes in psoriasis can express K6 or K10 depending on their localization in involved or uninvolved skin. There is a unique subpopulation of cells in the psoriatic plaques which co-express K6 and K10. More studies are required to fully understand the pathogenic relevance of co-expression and single expression of K6 and K10.
Department of Dermatology, University Medical Centre Nijmegen
PO Box 9101
NL–6500 HB Nijmegen (The Netherlands)
Tel. +31 24 3617238, Fax +31 24 3541184, E-Mail R.Mommers@derma.azn.nl
Received: Received: May 21, 1999
Accepted: January 13, 2000
Number of Print Pages : 6
Number of Figures : 4, Number of Tables : 0, Number of References : 22
Dermatology (International Journal for Clinical and Investigative Dermatology)
Founded as ‘Dermatologische Zeitschrift’ by Oskar Lassar (1893–1907); Continued by Erich Hoffmann (1908–1938), continued as ‘Dermatologica’ (1939–1991), by Wilhelm Lutz (1939–1958), Rudolf Schuppli (1959–1985)
Official Organ of the Swiss Society for Dermatology and Venereology; Official Organ of the Belgian Royal Society for Dermatology and Venereology
Vol. 201, No. 1, Year 2000 (Cover Date: 2000)
Journal Editor: J.-H. Saurat, Geneva.
ISSN: 1018–8665 (print), 1421–9832 (Online)
For additional information: http://www.karger.com/journals/drm
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