The combination of the Zenon labeling technique and microscopic image analysis to study cell populations in normal and psoriatic epidermis

Abstract

In order to better characterize epidermal cell populations in psoriatic vs. normal skin, fluorescent immunohistochemical techniques were extended with a new labeling technique. The Zenon technique conjugates primary antibodies rapidly and quantitatively after which they are used in the same manner as covalently labeled primary antibodies. Digital microscopic images of epidermal expression of keratin 10 and keratin 6 (differentiation), Ki-67 antigen (proliferation), and keratin 15 and beta-1 integrin (basal layer) were analyzed in a standardized way. Co-expression of different proteins was demonstrated. Sections of normal skin and psoriatic lesions were compared immunohistochemically. Antibodies against keratin 6, 10, and 15 were labeled with the Zenon technique. Antibodies against the Ki-67 antigen and beta-1 integrin were covalently fluorescein isothiocyanate-labeled. Using standardized image analysis, intensity and positive surface area of the different antibodies in the epidermis were measured. The number of Ki-67-antigen positive cells was significantly increased in lesional psoriatic skin. Intensity and positive surface area of keratin 10 and beta-1 integrin were significantly decreased in comparison to normal epidermis. Differential expression of keratin 6 and keratin 15 was demonstrated. Using Zenon technology and image analysis, a description of morphology, co-expression, and quantification of representative markers for epidermal cell populations is possible.