Skin biopsies from five healthy subjects, taken before and after UVB irradiation, were examined using immunohistological techniques for the cytokines interleukin-I (IL-I) and tumour necrosis factor (TNF). Using polyclonal specific antibodies against IL-I and TNF, the two cytokines appeared identically located on the epidermal cell membranes of the stratum granulosum and stratum spinosum in unexposed skin. After UVB-exposure, the staining intensity for both IL-I/epidermal cell derived thymocyte-activating factor (ETAF) and TNF was markedly increased, and the epidermal staining included the basal cell layer. Immunohistological investigation of tissue-bound epidermal cytokines may be valuable in the study of skin diseases.

tumour necrosis factor a and interleukin 6 in AIDS-related Kaposi's sarcoma -An immunohistological study. APMIS 97: 533-538, 1989.Biopsies from 6 patients with AIDS and Kaposi's sarcoma (KS) in the tumour stage, and 6 healthy controls, were immunohistologically examined for the presence of tissue-bound tumour necrosis factora (TNFa) and interleukin 6 (IL-6) in the skin. TNFa was demonstrated using specific polyclonal antiserum to human recombinant TNFa. IL-6 was visualized indirectly using a polyclonal antiserum to partially purified human crude supernatants of activated human blood monocytes, followed by absorption with recombinant human IL-6. The cytokines were found identically located in epidermal cell membranes in stratum granulosum and spinosum of the epidermis from unaffected skin in both AIDS patients and in controls. Biopsies from KS elements showed markedly increased epidermal staining for both TNF 6 and IL-6. It was not possible to detect TNFa or IL6 in the endothelial cells of the tumour. The observation of increased amounts of epidermal-bound TNFa and IL-6 in AIDS-related KS elements suplements previous studies indicating that the skin plays an active immunoinflammatory role in patients with AIDS.

The presence of human cytokines was examined in parallel skin biopsies and epidermal single cell preparations obtained from normal individuals. Using biotin‐avidin‐peroxidase and immunofluorescence techniques and antibodies against recombinant cytokines, a granular intercellular/membrane‐associated staining for interleukin‐6 (IL‐6) and tumour necrosis factor alpha (TNF alpha), but not IL‐1 alpha or beta, was observed. An epidermal cytoplasmic staining pattern was also detected, which was most pronounced using the anti‐rIL‐6 antiserum. In the epidermal single cell preprations, membrane‐associated staining was detected for both IL‐6 and TNF alpha. Double staining revealed that CD1‐positive Langerhans cells (LC) failed to express any of the examined cytokines. In vitro binding of rIL‐6 or rTNF alpha to skin sections and epidermal single cell preparations indicated that the cell surface‐associated IL‐6 and TNF alpha originally demonstrated on keratinocytes were truly membrane‐bound. Finally, co‐cultivation of epidermal cells with an IL‐6 responsive cell line, B9, and testing of epidermal cell supernatants in this assay, indicated that the in vivo membrane‐bound IL‐6 had biological activity.

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