Circulating IgG from patients with primary Sjögren's syndrome deposited in the epidermis of normal human skin transplanted to athymic nude mice.

Sera from 7 patients with primary Sjögren's syndrome and from two control persons were administered intraperitoneally to athymic nude mice transplanted with normal human skin. Seven days after transfer of serum from 5 of the patients, intra-epidermal IgG1 and IgG3 deposits were demonstrated in the skin grafts by immunofluorescence. The deposits closely resembled in vivo deposits found in the skin of these patients. No correlation was found between the presence of epidermal deposits and levels of IgG1 and IgG3 in serum. No IgG deposits were found in skin grafts on animals given control serum, and neither could human IgG be detected in mouse skin adjacent to the grafts. Epidermal deposits of human-IgM, -IgA, -fibrinogen, -C3c and mouse-Ig were not demonstrated in biopsies from grafts or mouse skin. The results support the hypothesis that epidermal in vivo deposits of IgG in patients with primary Sjögren's syndrome are the result of Fc-receptor-mediated binding to epidermal cells.