X-ray irradiation of the human epidermis in vitro. II. Comparison of a single 44 kV and 200 kV x-ray irradiation

On example of the reduction of epidermal binding of FITC-wheat germ agglutinin (WGA) the direct membrane effect of a single roentgen irradiation (44 kV and 220 kV) was analysed in vitro. Human normal skin and psoriasis centre were compared. Normal skin showed no alteration of light-microscopically visible FITC-WGA-binding on epidermal cells over the whole doses range. Psoriatic lesions responded to doses of greater than or equal to 5 Gy (44 and 220 kV) with a drastic reduction of epidermal lectin adhesion to lower and middle cell layers. The maximum of efficacy was with 5 Gy (44 kV) or 10 Gy (220 kV). A dose elevation up to 20 Gy did not result in an increase of efficacy. Topographically the radiosensitive FITC-WGA-binding could be seen in the rete ridges above all. The findings support the impression of an increased radiosensitivity of the lesional psoriasis epidermis compared with normal skin. The causes for this are seen in an abnormal differentiation of keratinocytes in psoriasis.