Novel quantitative immunofluorescent technique reveals improvements in epidermal cell populations after mild treatment of psoriasis

A novel antibody labelling technique, the Zenon technique, was used in fluorescent immunohistochemistry for a better characterization of epidermal cell populations in a quantitative approach. With this technique, differences in proliferation and differentiation characteristics were shown between psoriatic and normal epidermis. The sensitivity of the method was investigated by assessing the effect of a mild topical treatment versus an emollient. Frozen sections of non-treated psoriatic epidermis and psoriatic epidermis treated once daily with either an emollient or betamethasone-17-valerate for only 2 weeks were compared immunohistochemically. Antibodies against keratin 6, 10 and 15 were labelled with the Zenon technique, whereas antibodies against the Ki-67 antigen and beta-1 integrin were covalently FITC-labelled. Using image analysis, these markers were measured in the epidermis in a standardized manner. Treatment of psoriasis with short-term topical steroid resulted towards normalization of Ki-67 antigen, beta-1 integrin, keratin 10 and keratin 6 expression, which are parameters for proliferation and differentiation. Although treatment with an emollient showed hardly any clinical response, changes towards a more normal phenotype could already be detected in several epidermal markers using this method.