Fc? receptors on keratinocytes in psoriasis

Abstract

Epidermis in cryostat sections of skin biopsy specimens from patients with psoriasis and from healthy individuals bound bovine erythrocytes (E) sensitized with rabbit IgG antibodies (A)(EA). No binding occurred using E or E sensitized with IgM or F(ab')2 fragments of IgG. The binding of EA was inhibited by human IgG and by Fc fragments of IgG, whereas human IgA, IgM, albumin, and F(ab)2 fragments of IgG did not inhibit the binding, indicating the presence of receptors for the Fc part of IgG (FcR). EA bound mainly to stratum spinosum and most strongly above FcR-positive cell infiltrates in dermal papillae. The binding of EA to sections from patients with active psoriasis was stronger than to sections from patients with stationary psoriasis vulgaris. Sections of unaffected skin from patients with psoriasis and healthy individuals also bound EA, but the binding was weaker than to sections of psoriatic lesions. The receptors were sensitive to periodic acid, formaldehyde, and heat. Using immune complexes of horseradish peroxidase (HRP) and rabbit IgG antibodies to HRP, the receptors were localized to the outer aspect of the keratinocytes and to the inflammatory cells in the microabscesses. The strongest binding occurred in the same areas which adhered EA most strongly. FcR on dendritic epidermal cells could not be demonstrated in situ. A monoclonal antibody against FcR also stained the outer aspect of most keratinocytes throughout the epidermis. FcR on keratinocytes support the assumption that these cells contribute to immune reactions in the skin.

Ultrastructural and Immuno‐electron Microscopic Study in a Case of Epidermolysis Bullosa Acquisita

“…According to the histological and clinical picture of the disease, EBA belongs to the epidermolysis bullosa group of diseases (8, 151, and the term ))mechanobullous dermatosescc has been proposed (2, 13). The case presented fulfils the clinical and histological criteria for the diagnosis for EBA as discussed elsewere (9). The electron microscopic findings eith blister formation below the lamina densa in bo,th skin lesions and friction blisters are in keeping with electron microscopic studies of skin lesions in a few reported cases of EBA ( I , I 3, 1 5 , 17).…”

“…Initially he was treated with prednisone and azathioprine without improvement. From February I978 he was successfully treated with gold sodium thiomalate, reaching a total dose of 1000 mg. A detailed description of the clinical course is given elsewhere (9). Hisropathological Studies.…”

In situ localization of interferons in psoriatic lesions

“…Recently, we demonstrated FcR on keratinocytes in normal and psoriatic skin [13]. Enhanced FcR activity by keratinocytes was found in psoriatic skin lesions compared with normal skin and strongest above areas with mononuclear cell infiltrates.…”

“…The presence of IFN-e in the basal keratinocytes and in epidermal dendritic cells may therefore influence the HLA-DR expression induced by IFN-7. According to Yasutaka et al [34] crosslinking of FcR on various cell lines in vitro inhibited the ability of IFN-7 to induce HLA-DR. An in vivo cross linking of FcR on keratinocytes [13] may therefore be another explanation for the reduced expression of HLA-DR on keratinocytes in psoriatic lesions.…”

“…In some experiments the MoAbs were diluted in PBS-containing human IgG (8 mg/ml) to prevent binding to receptors for the Fc part of IgG [13]. Preliminary experiments showed that the anti-IFN-c~ antibody stained sections of active psoriasis up to a dilution of I in 4096, and the anti IFN-y antibody up to a dilution of 1 in 1024.…”