Evaluation of an avidin-biotin-peroxidase method with a monoclonal antibody to type IV collagen in the differential diagnosis of bullous pemphigoid and epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita in a great Dane

Autoimmune subepidermal blistering diseases in dogs were all classified as bullous pemphigoid until 1998. Since then, refinements in reagents and immunological techniques have allowed diseases which are histologically similar but which have a different molecular pathogenesis to be described. This report describes the first case of one such disease, epidermolysis bullosa acquisita, to be documented in the UK. The dog presented with a severe blistering and ulcerative disease affecting the oral cavity, pinnae and distal limbs. The diagnosis was confirmed by histopathology and direct and indirect immunofluorescent demonstration of immunoglobulin G reactivity to basement membrane antigens. Treatment with glucocorticoids, azathioprine, colchicine and an intravenous infusion of immunoglobulins resulted in complete resolution. The drugs were discontinued 12 months after the start of treatment and the dog remained in remission.

[Relevance of histological examination in the diagnosis of autoimmune bullous dermatoses]

The histopathological picture of many autoimmune bullous dermatoses is considered to be relatively characteristic. However, different entities may show similar histological findings. In addition, the picture depends on both the stage of the disease and prior treatment. Autoimmune bullous dermatoses are characterized by the production of autoantibodies to structural proteins of the skin. In most instances, the autoantigens have been identified and are available as recombinant proteins. Utilizing these recombinant forms, specific and sensitive assays have been developed for the detection of circulating autoantibodies in the serum. The detection of autoantibodies in skin or mucous membranes and/or serum is required for the diagnosis of autoimmune bullous dermatoses. The task of the dermatopathologist in the diagnostic process of autoimmune bullous dermatoses is to describe precisely the histopathological findings, to mention differential diagnoses and to recommend how these can be confirmed or excluded by immunopathological and immunoserological studies.

Morphogenesis of MDCK cells in a collagen gel matrix culture under stromal adipocyte-epithelial cell interaction

BACKGROUND

The stromal-epithelial cell interaction is essential for epithelial morphogenesis. Recently, the specific stromal cell type adipocytes, which abundantly exist in perirenal adipose tissue, have been suggested to affect the biological behavior of some epithelial cell types. However, adipocyte-renal epithelial cell interaction remains unclear. We thus examined the effects of adipocytes on the morphogenesis of renal epithelial cells.

METHODS

The renal epithelial cell line, Madin-Darby canine kidney (MDCK), cells were cultured in three-dimensional collagen gel matrix with or without mature unilocular adipocytes. Cultures cells were examined by histochemistry, immunohistochemistry, and electron microscopy.

RESULTS

Adipocytes extensively promoted the tubule formation of MDCK cells in two different manners. In the first type, after approximately 20% of MDCK cells actively adhered to adipocytes; they organized double-cell structured tubules between the adipocytes and the gel, contacting directly with the entire surface of the adipocytes. In the second type, approximately 70% of MDCK cells apart from adipocytes also formed tubules that had no contact with adipocytes. The component cells of both tubule types at the apical side showed microvilli and peanut agglutinin lectin-positive stain. These cells at the basal side had the basal lamina and type IV collagen-positive stain.

CONCLUSIONS

These results indicate that the specific stromal cell type adipocytes cause MDCK cells to organize the well-polarized tubular structures in two different manners according to their direct and indirect interactions, suggesting that adipocytes may be involved in the regulatory mechanism of renal epithelial morphogenesis.