The immunohistochemical distribution of the epidermal proteins filaggrin, involucrin, and cytokeratins is characteristic in normal epidermis. This distribution may change as a result of malignant transformation or abnormal differentiation. The present study was conducted to determine the patterns of reactivity of psoriatic epidermis to antibodies against various epidermal proteins and to clarify abnormal differentiation or maturation of the keratinocytes in psoriatic epidermis. Anti-human filaggrin, anti-human involucrin, and twelve kinds of anti-cytokeratin antibodies were used in this study. Cryostat or paraffin-embedded sections were stained with these antibodies by the avidin-biotin peroxidase technique. The epidermis of the noninvolved skin of patients with psoriasis vulgaris showed the distribution seen in normal skin. However, involved psoriatic skin revealed little or no reaction in the stratum corneum or in the granular layer with the anti-filaggrin antibody. Cells positively staining with anti-involucrin antibody paradoxically appeared in the lower cell layers of involved psoriatic epidermis. An anti-keratin antibody, AE1, stained suprabasal cells in involved psoriatic epidermis, although this antibody selectively stained epidermal basal cells in normal skin. The other anti-keratin antibodies, especially KL1, PKK1, and a polyclonal anti-keratin antibody, were less reactive with involved psoriatic skin than with normal skin. These observations suggest that the maturation pathway of keratinocytes in active psoriatic lesions differs qualitatively from that in normal epidermis.

The expression of cytokeratins and involucrin varies greatly in different epithelia, and this raises the possibility that detailed analysis of these epidermal proteins might proiade a means of identifying various skin tumours. The present study was conducted to determine the immunohistochemical distribution of cytokeratins and involucrin in calcifying epithelioma of Malherbe. in order to elucidate the nature and differentiation of this tumour. To correlate the immunohistochemical profile with the most frequent histological patterns, we categorized the basophilic, transitional, shadow, and squamoid cells, and the shreds of keratin. Comparative studies with normal skin showed that the shadow and transitional cells corresponded to hair cortex cells, the squamoid cells to the outer root sheath, the basophilic cells adjacent to the stroma to the outermost cell layer of the outer root sheath between the lower permanent portion and upper transient portion of the follicles, and the basophilic cells adjacent to the transitional cells to the hair matrix. The expression of cytokeratins in most shreds of keratin was similar to that in squamoid cells. Calcifying epithelioma was, therefore, shown to be composed of tumour cells differentiating into both the hair cortex and outer root sheath. These tumour cells were differentiated from basophilic cells, which showed the same staining patterns as the outermost cell layer of the outer root sheath between the lower permanent portion and upper transient portion of the hair follicles, supporting the hypothesis that the keratinocytes in the outermost cell layer can differentiate into the transitional portion of the follicle and anagen hair.

One of the most common dermatological side effects of cyclosporin A (CsA) is dose-dependent hypertrichosis. Similar hair growth was noted in nude mice in an attempt to increase the acceptance of human xenografts with CsA in the T-cell-deficient congenitally athymic nude (nu/nu) mice. The aim of the present study was to further investigate the stimulation of hair growth on nude mice not only by oral administration of CsA but also by topical and subcutaneous administration of CsA. Young BALB/c female nude mice were treated for 3 or 4 weeks with topical, oral, or subcutaneous applications of CsA dissolved in olive oil at various doses. The hair of CsA-treated mice appeared to grow from 7 days after the treatment, even at low doses. Induced hair growth was dose-dependent and became clearly obvious 3 weeks after the treatment. The stimulation of hair growth was not restricted to the site of topical application. The distribution of the new hair depended on the natural pattern of hair growth in the mice. However, there was no hair growth in the control mice which were given only olive oil. Histological examination revealed that there were no differences in the structures of skin and hair between the control and the CsA-treated mice. Furthermore, the number of hair follicles did not remarkably increase after CsA treatment. The hair growth in the CsA-treated mice stopped after cessation of the treatment and returned to the level of the control mice on day 14 after the end of the treatment. Subsequent retreatment with CsA resulted in further regrowth of the hair.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibody (moAB) OKB19 reacts with CD19 antigen, which is the broadest lineage-specific surface marker on B-lymphocytes. In frozen tissue sections, using an immunohistochemical technique, the OKB19-positive cells in the basal layer were sharply demarcated from the negative suprabasal layers. In normal hair follicles, the OKB19 reactivity was also confined to one layer of the dermal side of the outer root sheath. However, this reactivity gradually disappeared in the lower areas. The inner surface of the lumina in the eccrine duct was weakly stained with OKB19. The basal keratinocytes were also stained with OKB19 in the lesional epidermis of the various dermatoses examined in this study, when the basal keratinocytes remained unaffected. Even in the hyperproliferative state of psoriasis, the OKB19 reactivity was confined to the basal layer. Several kinds of tumor cells derived from the skin were not stained with OKB19. No labeling was seen even in the basaloid cells of basal cell carcinoma, which are morphologically similar to basal keratinocytes. B4 and Leu-12, other monoclonal antibodies reacting with CD19, did not recognize any keratinocytes in the normal human skin. MoAB OKB19, therefore, reacts with an antigen present on basal keratinocytes and provides a probe for the isolation of the basal keratinocyte subpopulation. Thus, this antibody should be useful in studies of not only B-lymphocyte differentiation, but also normal and aberrant differentiation of the epidermal keratinocytes.

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