Proliferation of Protease-enriched Mast Cells in Sarcoptic Skin Lesions of Raccoon Dogs

Abstract

Skin sites, tongue, lung, liver, jejunum and rectum from two raccoon dogs with Sarcoptes scabiei infestation and five normal (control) raccoon dogs were examined in terms of the distribution, proteoglycan properties and protease activity of mast cells. Infestation with S. scabiei caused a significant increase in the number of dermal mast cells. While the number of mast cells (average±standard deviation) in specimens of skin from the dorsum, dorsal neck, dorsal hind foot and dorsal fore foot was 40.0±19.8/mm 2 in control animals, it was 236.1±58.9/mm 2 in the skin of mange-infested animals. Histochemical analysis revealed the glycosaminoglycan, heparin, within the mast cells of all organs examined in both control and affected animals. Enzyme-histochemical detection of serine proteases demonstrated an increase in mast-cell-specific protease activity (i.e., chymase and tryptase) in the skin of infested animals. The percentage of mast cells demonstrating chymase activity was 53.0±27.4% in control animals and 73.8±19.4% in mite-infested animals. The corresponding results for tryptase activity were 53.5±25.2% and 89.4±9.8%. Increases in mast cell chymase or tryptase activity, or both, were also observed within other organs of the infected animals, but the total number of mast cells found at such sites (with the exception of liver and ventrolateral pinna) did not differ from those of control animals.