P-selectin expression in canine cutaneous inflammatory diseases and mast cell tumors

P-selectin, a member of the selectin family of adhesion molecules, mediates the initial adhesion of leukocytes to the blood vessel wall during their e migration from the circulation. Adhesion molecules play an important role i n the pathogenesis of several diseases, including various skin conditions. The objectives of the present study were to characterize the expression of vascular P-selectin in the skin of dogs suffering from inflammatory disease s or from common cutaneous neoplasms, and to determine if a correlation exi sts between P-selectin expression and inflammatory cell infiltration in the se conditions. Immunohistochemistry was performed on formalin-fixed canine skin using a specific anti-canine P-selectin monoclonal antibody (MD3). Res ults showed that P-selectin was minimally expressed it normal canine skin. However, the number of P-selectin-expressing blood vessels was significantl y increased (P < 0.05) in cases of allergic dermatitis, autoimmune dermatit is, pyogranulomatous dermatitis, dermatophytosis, and panniculitis. Highest P-selectin expression (per centage of MD3-positive vessels and intensity o f the reaction) was observed in cases of autoimmune and pyogranulomatous de rmatitis (55.3 +/- 7.4 and 44.0 +/- 9.9% P-selectin-positive vessels, respe ctively). In all conditions studied, a positive correlation existed between the number of P-selectin-positive blood vessels and the number of infiltra ting leukocytes (r = 0.556, P < 0.01). A significant number of blood vessel s in mast cell tumors also expressed P-selectin, whereas no staining was ob served in any of the histiocytomas examined. These results reveal that P-se lectin expression is increased in different types of canine inflammatory sk in diseases and suggest that P-selectin could participate in the local recr uitment of leukocytes in canine cutaneous diseases.