Intraepithelial gamma delta T cells are closely associated with apoptotic enterocytes in the bovine intestine.
The T cell population in the intestinal epithelium, comparable in size to the T cell pool in the spleen, is characterized by the predominant distribution of T cells bearing gamma delta T cell receptors. To determine the functional significance of the intraepithelial lymphocytes, we observed gamma delta T cells present in the jejunal epithelium in cattle, in which there is predominance of gamma delta T cells. Immunohistochemistry of frozen sections demonstrated that gamma delta T lymphocytes were densely distributed in the villous epithelium but there were fewer in the lamina propria and they were not present in the crypt epithelium. Ultrastructurally, intraepithelial gamma delta T cells were characterized by possessing electron-dense granules and interdigitating with enterocyte cytoplasm. Enterocytes, which were inserted by processes of intraepithelial lymphocytes or contacted by their cell bodies, showed morphologic changes seen in apoptotic cell death, such as elevated electron density of the cytoplasm and condensation of the chromatin. Apoptotic cells and cell debris were found in macrophages, which gathered in the subepithelial region of villus tips. These findings suggest that in the small intestine of cattle, gamma delta T cells are involved in the renewal of epithelial cells by inducing apoptosis of epithelial cells.
Suzuki
Y
Y
Laboratory of Anatomy, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Mori
K
K
Iwanaga
T
T
D000818:Animals; D017209:Apoptosis; D002417:Cattle; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000276:immunology* / Q000648:ultrastructure; D007421:Intestine, Small / Q000276:immunology* / Q000648:ultrastructure; D008264:Macrophages / Q000166:cytology / Q000648:ultrastructure; D008854:Microscopy, Electron; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure
D016692:Receptors, Antigen, T-Cell, gamma-delta