RESUMEN
Mastocytomas are the most common malignant neoplasm in the dog; they are more aggressive than the mast cell tumors of other species. Therefore, it is imperative to develop a highly sensitive and specific immunoassay for clinical diagnosis of canine mastocytoma. The production and characterization of new mouse monoclonal antibodies (MAb 9-3 and MAb 80) directed against canine mastocytoma are reported here. By immunohistochemistry using fresh frozen tissue of tissue impression smears, we observed that the antigen recognized by MAb 9-3 is expressed exclusively on the surface and cytoplasmic granules of canine mastocytoma but not on the mast cells in normal canine skin. MAb 80 did not compete for binding to mast cells in normal canine skin. Western blot assays performed with canine mastocytoma indicated that MAb 9-3 recognized the 74 kDa band, and MAb 80 recognized the 167 and 248 kDa bands. We studied the immunostaining pattern of impression smears with MAb 9-3 from 36 benign and malignant canine masses, including eight samples of mastocytoma that were positive and other tumor samples that were negative by MAb 9-3. This report for the first time precisely characterizes a monoclonal antibody specific for canine mastocytoma, facilitating clinical and molecular investigation of canine mastocytoma.
