Antigenic similarities and differences in genus Pityrosporum.

Using the indirect immunofluorescence technique no differences were observed in intensity of staining when antisera against Pityrosporum orbiculare and P. ovale or IgG fractions of these were incubated with P. orbiculare and P. ovale cells. However, a weaker reaction was observed with these antisera and P. pachydermatis cells. With IgG fractions the nonspecific fluorescence was minimized. Fungal cells in biopsies from tinea versicolor lesions showed a brilliant staining with the IgG fractions of antisera against P. orbiculare. This investigation indicates a close antigenic relationship between all of the 3 Pityrosporum species. A common antigenicity was found between P. orbiculare and P. ovale cells as well as between P. orbiculare cells from culture and the fungal cells in biopsies from tinea versicolor lesions. This strongly suggests that these 2 species are identical with each other and with the organism found in tissue.

A simple in vitro technique for studies on induction of class II transplantation antigens on keratinocytes.

A new technique is described for evaluation of the induction and kinetics of class II transplantation antigens on keratinocytes. By culturing small rat or human skin specimens for 2-5 days in media containing gamma-interferon, class II antigens were detected on keratinocytes by immunohistochemistry. This technique is rapid and technically simple compared to keratinocyte cultures and raises the possibility of studying other cells in the skin.

Expression of Ia antigen-like molecules on cells in the corneal epithelium.

Ia antigens, known to be expressed preferentially on cells of the immune system, have been shown to be present on cells in the cornea. By immunofluorescence studies, it was shown that a specific rabbit anti-Ia antigen serum stained cells in the corneal epithelium. The stained cells were well integrated into the corneal epithelial architecture and displayed short dendritic processes. Their location in the cornea and corneal limbus and their morphological appearance make it reasonable to suggest that the Ia antigen-expressing cells of the cornea are equivalents of the Ia antigen-bearing Langerhans' cells of the epidermis.

Immunological markers of Langerhans' cells in mycosis fungoides skin lesions.

The patterns of two immunological markers of epidermal Langerhans' cells were compared in normal skin and mycosis fungoides (MF) skin lesions. A double-staining indirect immunofluorescence method was used. Cells suggestive of keratinocytes reacted with the anti-Ia antibodies in some cases of MF lesions, while no such pattern was seen with the thymocyte-antigen antibodies (OK T6). In other cases of MF, as in normal skin, the epidermal picture was mainly the same with the two markers. A great many of the dermal mononuclear cells in MF were reactive with the anti-Ia antibodies but only occasional dermal cells in MF and no dermal cells in normal skin stained with OK T6.

Ia-like antigens in lichen planus.

The occurrence of Ia-like antigens in the skin of patients with lichen planus was studied by an indirect immunofluorescence (IIF) technique with use of immunosorbent-purified anti-Ia antibodies. Normal skin from the patients and skin from healthy persons showed dermal histiocytes and epidermal suprabasal dendritic cells expressing these antigens. In lichen planus lesions Ia-like antigens were found on virtually all mononuclear cells in the dermal infiltrate and showed an intercellular pattern in the epidermis. The finding of cells expressing Ia-like antigens in the dermal infiltrate, most probably activated T lymphocytes, renders likely a cell-mediated type of reaction in the pathogenesis of lichen planus.

Amplification of T-cell response to PPD by epidermal cell suspensions containing HLA-DR-expressing keratinocytes.

The biological importance of the presence of class II transplantation antigens on highly differentiated epithelial cells such as keratinocytes in certain conditions, is still unknown. We have therefore investigated the antigen-presenting capacity of separated human epidermal cells obtained from tuberculin-reactive skin 6 days after intradermal injection of purified protein derivative (PPD). Earlier studies have shown a high percentage of HLA-DR-expressing keratinocytes at this time. Peripheral adherent blood cells were used as control stimulator cells and highly purified peripheral blood T lymphocytes as responder cells. The T-cell proliferation in response to PPD in the presence of autologous epidermal cells from normal and tuberculin-reactive skin was measured by [3H]thymidine incorporation on day 6. The latter cell population, 76-86% of which consisted of HLA-DR-expressing cells as judged by immunocytochemistry, induced a greater T-cell response to PPD than do normal epidermal cells. This discrepancy in the T-cell proliferation could not be explained by a difference in the numbers of anti-Leu 6 or anti-HLA-DQ-reactive Langerhans cells. The present data indicate that epidermal cell suspensions containing HLA-DR-expressing keratinocytes induce a greater T-cell response to PPD than do normal epidermal cells.

Class II transplantation antigens in the late human skin tuberculin reaction.

The presence of class II transplantation antigens on keratinocytes and the phenotypes of the inflammatory cells in the late human skin tuberculin reaction were analysed with immunohistochemical double staining techniques in frozen sections of skin biopsies taken 10-45 days after intradermal purified protein derivative (PPD) injection. Dermal cell infiltrates decreased with time but were found throughout the observation period. Most of the cells in the perivascular infiltrates expressed HLA-DR antigens. Some of these cells are probably 'activated' macrophages, since they expressed OKM1 and OKT9 antigens in consecutive sections. Another less frequent cell population which reacted with RFD1 antibodies are presumably interdigitating cells. About half the perivascular cells were anti-Leu 3a-positive (T 'helper/inducer' phenotype). HLA-DR but not HLA-DQ antigens were detected on keratinocytes. This acquired expression of HLA-DR antigens on the epithelial cells disappeared between 17 and 30 days. If HLA-DR-expressing keratinocytes have immunoregulatory functions these might be different from those of other HLA-DR-expressing cell types that also express HLA-DQ molecules.

Human keratinocytes express HLA-DR antigens in the tuberculin reaction.

The cellular response in the human skin tuberculin reaction was studied with immunohistochemical double-staining techniques in frozen sections of skin biopsies taken 6 h to 8 days after intradermal PPD injections. Cell infiltrates were observed from day 2 onwards and increased in size up to 4 days. Most of the infiltrating cells reacted with anti-Leu 3a (T 'helper/inducer' phenotype) antibodies. In contrast to normal epidermis, not only Langerhans cells but also keratinocytes expressed HLA-DR antigens from day 4 onwards. The induction of HLA-DR antigens on keratinocytes may be secondary to T-cell activation. Since the HLA-DR expression on keratinocytes appeared late in the tuberculin reaction, the function may be to suppress rather than enhance the immune response.

Distribution of interleukin-2 receptor bearing lymphocytes in the skin. A comparative study of allergic and irritant contact dermatitis, tuberculin reaction and cutaneous T cell lymphoma.

The tissue distribution of T cells and interleukin-2 receptor bearing (Tac+) lymphocytes was studied immunohistochemically in frozen sections of biopsies from inflamed skin. In skin lesions caused by irritant or immunologic stimuli, relatively few (less than 5%) of the total dermal infiltrating T cells were Tac+, but in both types of conditions the Tac+ cells showed a predeliction for the epidermis. In skin lesions from patients with cutaneous T cell lymphoma a relatively high proportion of dermal T lymphocytes were Tac+. Tac+ as well as Tac- T lymphocytes may thus migrate to a tissue secondary to several different stimuli. The demonstration of a non-random distribution of Tac+ lymphocytes in the non-malignant inflammatory conditions in the present study indicate that the epidermis may have a special role in the activation of T lymphocytes.

In vitro testing of contact sensitivity.

A new in vitro technique for the testing for contact sensitivity is described. The method is based upon the fact that in response to immunological stimuli, keratinocytes can start to synthesize and express class II histocompatibility antigens. Nickel sulphate (NiSO4) stimulated lymphocytes from nickel-sensitive persons, and the supernatant of these cells thus induced expression of HLA-DR on keratinocytes when co-cultured with autologous normal skin biopsies. This was in contrast to what was the case in healthy controls.

Beta-2-microglobulin in basal cell carcinoma.

Differences in the cell surface of malignant cells, as compared with normal cells, are believed to be characteristic of many features of tumor cell behaviour. We have obtained evidence suggesting that solid and superficial basal cell carcinomas lack immuno-reactive beta-2-microglobulin (beta-2-m) on the cell surface, in contrast to normal epidermis and that of various non-malignant dermatoses, including basal cell papillomas.

Epidermal location of beta-2-microglobulin in human skin.

Beta-2-microglobulin (beta2-m) is associated with the epidermis in normal and pathological human skin and gives an immunofluorescence pattern similar to that of pemphigus antibodies and concanavalin A (Con-A). Inhibition experiments indicate, however, that the binding site of anti-beta2-m is not identical with that of pemphigus antibodies or Con-A. It is suggested that beta2-m might be an epidermal cell surface marker useful for the study of antigens associated with the epidermal cell surface.

Low dosage alpha-interferon treatment in patients with advanced cutaneous T-cell lymphoma.

Treatment with high dose (10-50 x 10(6) IU/m2 three times a week) of alpha-interferon (alpha-IFN) has been shown to induce remissions in about 50% of patients with cutaneous T-cell lymphoma. The optimal alpha-IFN dose, however, is not known. 4 patients with advanced cutaneous T-cell lymphoma were therefore treated with alpha-IFN in low doses of 2-4 x 10(6) IU/m2 three times a wk. 1 complete, 1 partial and 1 minor remission were observed. Skin biopsies before and during treatment were taken from 2 of the patients and showed improvement. Low doses of alpha-IFN can thus induce remission in patients with cutaneous T-cell lymphoma.