Lymphocytosis of large granular lymphocytes in three dogs

The clinical course and hematologic changes of three dogs with lymphocytosis of cells morphologically resembling large granular lymphocytes are presented. Hemograms from all dogs showed leukocytosis with marked lymphocytosis. Lymphocytes were characterized by abundant basophilic cytoplasm containing distinct granules which varied in size and number. Electron microscopically the granules were membrane-bound with an electron-dense core. Lymphocytes from one dog were positive for alkaline phosphatase activity, and lymphocytes from another dog were positive for alpha naphthyl butyrate esterase activity. Lymphocytes from one dog were positive for surface receptors for the crystalline fraction portion of gamma immunoglobulins.