British Journal of Dermatology (1976) 94, 7.

Hair follicle kinetics in psoriasis P.SHAHRAD AND R.MARKS Department of Medicine, Welsh National School of Medicine, Heath Park, CardifF Accepted for publication 12 May 1975

SUMMARY

The rate of epidermal cell production has been measured in the various parts of scalp hair follicles in patients with psoriasis of the scalp, and in controls with normal scalp skin. An in vitro technique was used in which thin tissue slices were exposed to tritiated thymidine enabling cells about to divide to become autoradiographically labelled. Biopsies from thirteen patients with psoriasis and nine controls were examined in this way. The labelling indices of the interfolUcular epidermis was 27-5" „ in the psoriaties and 9-5" „ in the controls. Theupper part of the external root sheath had a labelling index of 28%, in the psoriatic group compared to 13*9% for the controls. The labelling indices of the sebaceous glands,matricesandcxternalrootsheaths were very similar in the two groups. Tlie findings support the hypothesis for a dermal stimulating influence causingjhe increased epiderinopojesis seen i^^oriasis.

The increase in the rate of epidermal eell proliferation in psoriasis is well known. The heightened epidermopoicsis has been shown in a variety of ways. For example. Fisher & Wells (1968) found a three or four times increase in the mitotic index of psoriatic plaques using a colcemid induced mitotic arrest technique and Weinstein & Frost (1968) found an autoradiographic labelling index of 227'',', in the lesions of psoriasis after the intracutaneous injection of tritiated thymidine compared to 5-2''/, in normal skin. Similarly, Porter & Shuster (1968) found that there is an increased rate of transit of '"^^C labelled amino acids through psoriatic epidermis and Marks (1975) has demonstrated an increase in the rate of incorporation of tritiated thymidine by keratotome slices taken from patches of psoriasis. The hair originates from an epidermal structure (the pilosebaceous follicle), the constituent cells of which do not differ fundamentally from the cells of the interfollicular epidermis and have the same embryonic origin. It would not be unreasonable to suggest that the rate of hair growth might be increased in psoriasis paripassu with the observed increased rate of epidermal cell production. However, this does not appear to be the case and Comaish (1969) using ^^^S cystine demonstrated that the rate QL hair growth in psoriasis was in fact normal. There are important implications contained in the observation ornormatirair growth in psoriasis as far as the pathogenesis of the disease is concerned. In this investigation we have examined the rate of cell replication of the individual compartments of the pilosebaceous apparatus in the psoriatic scalp to determine whether any part of the hair follicle is involved.

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P.Skakrad and R.Marks PATIENTS AND METHODS

Thirteen patients with typical psoriasis of the scalp who had no treatment in the previous 3 weeks were investigated. There were 6 females and 7 males aged 22-65 years (mean 39-5 years). Nine patients (2 females, 7 males, aged 27-72 years, mean 46-8 years) with minor skin complaints not involving the scalp and no history of psoriasis were also examined. Punch biopsies (5 or 7 mm) were taken from all the patients and controls who had given their informed consent. The biopsies were cut into thin slices 1-2 mm thick using sharp, disposable scalpels (Gillette) and incubated in an orbital incubator (Gallenkamp) for 2^ h in unsupplemented Eagle's minimal essential medium at 37 C at high humidity and in an atmosphere of 95"o air and $'\ CO^. Tritiated thymidine (specific activity 20 Ci/mmole. Batch no. 43) was added to the medium in a concentration of 25 ;(Ci/ml at the start of incubation. The skin slices were removed from the medium at the end of incubation, fixed in 10% formalin and processed by routine histological methods. Paraffin sections were 'deparaffinized' and dipped in nuclear emulsion (Ilford K.2). They were then exposed in dark boxes for 2- and 3-week periods prior to development in Kodak developer D. 19. The developed sections were stained inhaematoxylin and eosin and mounted. Nuclei that had more than 6 grains above them over 'background' were counted as labelled cells. Only areas that were uniformly heavily labelled were assessed as there were areas in the centre of the tissue slices into which the thymidine had not diffused and where there was little or no labelhng. Labelling indices were determined for the matrix and the external root sheath by expressing the number of labelled cells present as a function of the total number of cells in that compartment. The upper external root sheath was separately assessed (that part above the entry of the sebaceous duct). Labelling indices for sebaceous glands were determined by expressing the number of labelled cells as a

FIGURE I. Interfollicular epidermis in biopsy from a patient with psoriasis of the scalp showing many autoradiographically labelled cells (H & E, x 150).

Hair follicle kinetics in psoriasis

FIGURE 2. Hair follicle in section from scalp biopsy of patient with psoriasis. There are many labelled cells in the matrix and external root sheath (H & E, x 90).

function of the number of peripheral cells of the gland lobules. Labelling indices for the interfollicular epidermis were assessed by expressing the number of labelled basal atid suprabasal cells as a percentage of the total number of basal cells. Between 400 and 2000 cells were counted for each 'labelling index'. RESULTS

Typical labelling obtained in interfollicular epidermis, in a sebaceous gland, in a hair follicle matrix and in an external root sheath of biopsy material derived from patients with psoriasis is shown in Figs I, 2 and 3 respectively. The labelling indices in the various parts of the hair follicles and in the interfollicular epidermis are given in Table i. There is a significant difference between the labelling indices for the interfollicular epidermis (P

Hair follicle kinetics in psoriasis.

The rate of epidermal cell production has been measured in the various parts of scalp hair follicles in patients with psoriasis of the scalp, and in c...
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