A form of autosomal dominant polycystic kidney disease (ADPKD) similar in clinical features to human ADPKD occurs in the Persian cat. We characterized the morphologic and immunohistochemical features of this disease in a colony of affected cats. Complete postmortem examinations were performed on 11 normal and 22 affected cats ranging in age from 3 months to 10 years. Kidneys were evaluated by gross and histologic examinations, ultrastructure, lectin staining, bromodeoxyuridine immunochemistry for labeling index and immunochemistry for distribution of Na/K ATPase. Feline ADPKD was characterized by variable numbers of cysts in the renal cortex and medullar. Ultrastructural examination and lectin staining suggested that cysts arose from proximal and distal nephron segments. Bromodeoxyuridine labeling demonstrated increased proliferation of epithelium lining some cysts in young cats. Immunohistochemical staining showed variable translocation of Na/K ATPase from the basolateral membranes of cyst-lining cells to the cytoplasm or luminal membranes. Cystic renal disease commonly was associated with chronic tubulointerstitial nephritis and hepatobiliary hyperplasia and fibrosis. Focal hyperplasia of renal tubular epithelium, hepatic cysts, and cardiac lesions were present in some cats. Feline ADPKD shares many morphologic and pathogenetic features with human ADPKD.

Intra-articular administration of APS can be considered an effective treatment option for equine osteoarthritis, with the potential for disease-modifying effects.

The inflammatory cells of eleven dogs with canine granulomatous meningoencephalitis were characterized immunohistochemically. Macrophages were identified by antibodies directed against lysozyme and the DH82 antigen (expressed by cells of a malignant histiocytosis). T cells were demonstrated by CD3, CD43, and CD45R antigen, and B cells by immunoglobulin G and immunoglobulin M expression. Furthermore, staining for the major histocompatibility complex (MHC) class II antigen was evaluated. Diseased animals ranged from 1 to 9 years of age. Small and medium-sized breeds were affected predominantly. Lesions were widespread and localized mainly in the brain stem, less frequently in the cerebrum or cerebellum. Alterations were represented by perivascular cuffs, parenchymal granulomas, and leptomeningeal infiltrates. Lymphocytes and macrophages comprised the dominant cell populations; their percentage varied substantially between different animals and between sections from the same individual. Immunohistochemically, the bulk of lymphocytes were CD3 antigen-positive T cells, while only a few cells were CD43 and CD45R antigen-positive or were classified as B cells. The majority of macrophages expressed both lysozyme and DH82 antigen; however, some were positive for only one antigen. MHC class II antigen-expression, observed only within and in close proximity to the lesions, was found on all inflammatory cells, pericytes/endothelial cells, and microglia. Results were negative for canine distemper virus antigen and nucleoprotein mRNA, rabies virus antigen, fungi, bacteria, and protozoal agents. This immunomorphologic study reveals that inflammatory lesions in canine granulomatous meningoencephalitis consist of a heterogeneous population of MHC class II antigen-positive macrophages and predominantly CD3 antigen-positive lymphocytes. The data suggest a T cell-mediated delayed-type hypersensitivity of an organ-specific autoimmune disease as a possible pathogenic mechanism for this unique canine brain lesion.

The DH82 cell line was established from the neoplastic progenitor cells of canine MH and was characterized as histiocytic in origin based on light microscopic and ultrastructural morphology, positive staining reactions for alpha naphthyl acetate esterase and acid phosphatase, presence of Fc receptors, phagocytosis of latex beads, and plastic adherence in culture.

No abstract