Perforin-like immunoreactivity in feline globule leukocytes and their distribution

Distributional and immunohistochemical characteristics of the feline globule leukocyte (GL) were investigated by light microscopy. The GL, which contained eosinophilic large granules in the cytoplasm, was frequently found in the epithelia of the intestine and gall bladder, and less frequently found in those of the gastric pit, intrahepatic bile duct, and interlobular secretory duct of the pancreas. No GL was seen in the respiratory and urogenital organs. The GLs composed a homogeneous cell population including no mast cells according to the following histochemical stainings; phosphotungstic acid hematoxylin, alcian blue and peroxidase. The feline GL showed perforin-like immunoreactivity to anti-human perforin monoclonal antibody, but did not show histamine-immunoreactivity to anti-histamine polyclonal antibody. The results suggest that the feline GL is a lineage of large granular lymphocytes. The epitheliotropism and characteristics as granular lymphocytes of the feline GLs were similar to those of the intestinal gamma delta T cells of the mouse.