Skin biopsies were obtained before and after PUVA therapy from the normal skin of 5 psoriatic patients. By electron microscopic morphometric techniques the pretreatment volume density of Langerhans cells within the epidermis was estimated to be approximately 1%. This density was reduced in all 5 patients after therapy. The volume density of Langerhans cell granules per Langerhans cell cytoplasm was on an average 0.8% and this density was reduced in 4 of the patients after therapy, while in one patient there was an increase. There was a reduced volume density of Langerhans cell granules per unit volume of epidermis in all 5 patients after therapy. The mean length of the Langerhans cell disc was 260 +/- 120, nm the mean thickness 40 nm and the mean diameter of the Langerhans cell vesicle 120 +/- 30 nm. None of these parameters changed after PUVA therapy. The reduced volume density of Langerhans cells is discussed in the context of possible implications for immune reactions in the skin.

A commercially available cell line (NCTC 2544) originating from presumably normal human skin was chosen as an in vitro model system for subsequent studies of the effects of different agents on human epithelial cells. The cell line, therefore, was ultrastructurally and otherwise characterized at intervals by techniques which allow standardized controls of the model. The cell line was classified as epithelial both by phase contrast microscopy and transmission electron microscopy. The cells were polygonal, fully developed desmosomes were demonstrated and no extracellular filamentous material was observed. Specific epidermal markers like keratohyalin granules or keratinosomes were not demonstrated. Comparison of the nuclear morphology of cells from 1, 3 and 6 days old cultures revealed that only minor changes took place. The same was true for cytoplasmic features. Thus this cell line has a well‐defined ultrastructural morphology. Flow cytometry studies showed the cell line to be tetraploid, with no sub‐populations with other ploidies. Surface antigens were typed by a microcytotoxicity assay using 12 different antisera. The electrophoretic patterns of the isoenzymes lactate dehydrogenase and glutathione reductase were human. The cells did not form colonies in soft agar. Though several parameters indicate that this cell line is not a HeLa cell contaminant, this possibility cannot, however, be totally excluded.

studies on the effect of photoactivated 8-methoxy psoralen. Nuclear changes in a human epithelial cell line. Acta path. microbiol. scand. Sect. A, 89: 81-90, 1981.An established human epithelial cell line was exposed to photoactivated 8-methoxy psoralen (PUVA); the cells were fixed and processed for electron microscopy 2 hours, 3 days and 6 days thereafter, and the nuclear morphology compared to controls. In the light microscope the cells fixed 3 and 6 days after PUVA exposure showed an increase in the number of multinucleated cells. At the ultrastructural level an increased number of cells with nuclear indentations, cytoplasmic invaginations, pseudoinclusions. nuclear bodies and multiple nucleoli were seen. An increased number of perichromatin granules per cell section and a decrease in heterochromatin situated marginally were observed. In cells from 6 day-old cultures I5 out of 50 nuclei were seen divided into 3-12 nuclear elements. compared with none in the controls. The smaller of these elements tended to be heterochromatic and the larger euchromatic. Generally the nuclear elements were smooth in outline. but elements of bizarre shape were also seen. These consisted of nuclear fragments united by heterochromatic extensions of uniform diameter. When comparing the morphology of PUVA exposed cells with the morphology of non-malignant and malignant cell lines, the PUVA exposed cells appeared to show an increase in morphological markers corresponding to those determined in malignant cells. The possibility that PUVA therapy may cause cancerous transformation is discussed.

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