R.M. Grood

Flow cytometry as a tool for the study of cell kinetics in epidermis

Flow cytometric measurements of the DNA content were performed on a large number of skin biopsies by an automated technique. Expressed as a percentage of all viable cells in the epidermis, the figures for cells in S‐phase averaged 1.8% and for G2M 0.9%. No significant differences due to sex were found. Concomitantly with age the ratio S/G2M (representing the duration of S to the duration of G2M) increased. Also seasonal effects were clear, showing higher values for S and G2M in June compared to November and December. Lastly we found small differences dependent on body‐site, the ratio S/G2M being greater in legs than in arms. The present status is discussed together with future lines of development.

Flow cytometric analysis of the recruitment of G0 cells in human epidermis in vivo following tape stripping

Abstract. Tape stripping of human skin elicits a proliferative response of a synchronously‐dividing group of cells. The progress of this cohort of cells has been monitored using two windows in the cell cycle, one located in mid‐S phase and the other centred around G2+ M. The cellular DNA is measured with flow cytometry, the windows are defined by two ranges in the DNA histogram.

Response of the clinically uninvolved skin of psoriatic patients to standardized injury.

Test sites on healthy controls and on the clinically uninvolved skin of psoriatic patients were stripped with tape, and eight variables were quantified at intervals during the subsequent healing process.

Metabolic changes at the margin of the spreading psoriatic lesion

Keratotome slices were cut across the margins of rapidly‐spreading psoriatic plaques. Each slice was divided into eight sections and in each section we measured the percentage cells in S phase and the levels of glucose‐6‐phosphate dehydrogenase (both related to epidermal proliferation), acid phosphatase (associated with keratinization) and alkaline phosphatase (a marker for dermal capillaries).

Flow cytometry as a tool for the study of cell kinetics in skin 2. Cell kinetic data in psoriasis.

Flow cytometry was used to measure the DNA content of epidermal keratinocytes from psoriatic patients. Gross deviations were found in the lesions and minor but significant changes in the uninvolved skin. Statistical analysis revealed that the rather large variation in the DNA distributions of the lesions was due to inter‐individual differences rather than to inter‐individual differences. The duration of the S‐phase seemed to be prolonged in the lesion, but the length of the overall cell cycle might be of the same order as that of normal skin.

Alteration of subcultured keratinocytes to a keratinizing epithelium

Subcultured epithelial cells from guinea‐pig ear skin were aggregated by means of nucleoprotein. After subsequent culturing under organ‐culture conditions, a more or less organized epithelium which formed a new stratum corneum was reconstituted.

Hyperdiploid cells in skin infiltrates.

We have developed a simple system based largely on parts of the Olympus OM camera system. The backbone of the apparatus is the bar with the bellows, equipped either with a 38 mm (/ 2 8) or a 20 mm {/2} macrolens. The camera body is a 35 mm SLR OM2 with an autoexposure electronic shutter. The bar carries a footplate tnade of 5 mm aluminium with a glass window with a diameter of about 35 mm along the optical axis. On one side the footplate carries an arm with the flash unit attached. The flash unit, equipped with a bright pilot light, is connected by a cable to the power control unit. The latter is fitted to the camera body by means of the flash shoe. The metering systetn of the camera automatically controls flash output, thus giving correct exposure under all conditions (Fig. i). Equipped with the 20 mm or 38 mm macrolens, the unit allows photographs to be taken with maximal magniflcations of up to x 16 or x 6 7 respectively. Photography of the skin with this apparatus is very simple. The footplate is put onto the skin with the pilot light on, either with or without immersion oil. Focusing and magniflcation are set by the knobs on the bellows. Once set, they can be kept fixed indeflnitely by tightening the knobs. Photos are taken, as with all cameras, by pressing the shutter release. Any of the vast number of different 35 mm films available may be used, including the new instant fllms. Our investigation of pigmented skin lesions (unpublished) has been done mainly with standard colour slide film, which allows easy secondary magnification by projecting the slides. Black and white films are also suitable. The simple apparatus described greatly facilitates macrophotography of the skin surface and skin lesions. Apart from possibly aiding in the differential diagnosis of pigmented skin lesions and their macroscopic changes with time, the system might also be of value for the documentation of vascular lesions before and after treatment. Other possible applications, e.g. in microlymphangiography, remain to be developed.

Flow cytometric investigations of corneocytes from psoriatic scales and the effects of Ingram therapy.

Flow cytometry has been used to study the stratum corneum. Following mechanical disruption and propidium iodide staining for DNA, analysis of the fluorescence intensity profile permits discrimination between nucleated and anucleate corneocytes. It was established that the nucleated corneocyte from parakeratotic stratum corneum contains double‐stranded DNA in the normal diploid amount.