Melanin granula distribution and phagocytosis in psoriasis vulgaris after PUVA therapy.

Melanin-containing basal cells of the epidermis, melanin-containing macrophages, mast cells, eosinophilic granulocytes and plasma cells were quantitatively investigated with the purpose of gaining an understanding of the quantitative changes in these cell systems under PUVA therapy. This patients have been exposed to solar radiation some weeks or months before the begin of the PUVA-treatment. Different dying-processes were used to investigate biopsy samples of psoriatically healthy and psoriatically affected skin, from 28 patients before, and 39 patients after PUVA therapy, using a 2 d micrometer with a field of view of 0.1 mm2. Altogether more than 9,000 fields of view have been analysed. The average radiation amount was 12 irradiations with an average total energy of 21.5 J/cm2. It was found that the count of granula-containing basal layer cells decreases in the psoriatic "healthy" region due to pigment incontinence and increase in the psoriatically affected region. The subepidermal melanin-containing phagocytes increase in both regions to a similar extent. In the case of the mast cells there was no trend to degranulation. The count of eosinophilic granulocytes and plasma cells was unchanged.