Biology of porcine T lymphocytes.
The present review concentrates on the biological aspects of porcine T lymphocytes. Their ontogeny, subpopulations, localization and trafficking, and responses to pathogens are reviewed. The development of porcine T cells begins in the liver during the first trimester of fetal life and continues in the thymus from the second trimester until after birth. Porcine T cells are divided into two lineages, based on their possession of the alphabeta or gammadelta T-cell receptor. Porcine alphabeta T cells recognize antigens in a major histocompatibility complex (MHC)-restricted manner, whereas the gammadelta T cells recognize antigens in a MHC non-restricted fashion. The CD4+CD8- and CD4+CD8lo T cell subsets of alphabeta T cells recognize antigens presented in MHC class II molecules, while the CD4-CD8+ T cell subset recognizes antigens presented in MHC class I molecules. Porcine alphabeta T cells localize mainly in lymphoid tissues, whereas gammadelta T cells predominate in the blood and intestinal epithelium of pigs. Porcine CD8+ alphabeta T cells are a prominent T-cell subset during antiviral responses, while porcine CD4+ alphabeta T cell responses predominantly occur in bacterial and parasitic infections. Porcine gammadelta T cell responses have been reported in only a few infections. Porcine T cell responses are suppressed by some viruses and bacteria. The mechanisms of T cell suppression are not entirely known but reportedly include the killing of T cells, the inhibition of T cell activation and proliferation, the inhibition of antiviral cytokine production, and the induction of immunosuppressive cytokines.
Charerntantanakul
Wasin
W
Department of Biology, Faculty of Science, Maejo University, Chiang Mai, Thailand.
Roth
James A
JA
D000818:Animals; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex / Q000276:immunology*; D013552:Swine / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II