Biology of porcine T lymphocytes

Abstract

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.

Vaccination with NS1-truncated H3N2 swine influenza virus primes T cells and confers cross-protection against an H1N1 heterosubtypic challenge in pigs

“…This is consistent with the established properties of porcine CD4 + CD8 + T cells, which are unique compared to other mammalian hosts in their high frequency outside the thymus [32]. The porcine CD4 + CD8 + population contains memory T helper cells that recognize antigens in an MHC class II-restricted manner [33]. The CD4 + CD8 + are multifunctional, as they express perforin and mediate antigen-specific cytolytic activity against virus-infected target cells [34,35].…”

Comparison of humoral and cellular immune responses to inactivated swine influenza virus vaccine in weaned pigs

“…The authors concluded that the vaccine was able to induce a systemic SIV-specific memory T cell response. We observed similar results by MP-FCM in that the inactivated vaccine could prime the CD4+CD8+ T cell subset, a population of T cells that have been demonstrated to be memory T cells in swine (Zuckermann and Husmann, 1996;Charerntantanakul and Roth, 2007). Although we did not measure antigen-specific proliferation, which is often used for evaluating antigenspecific recall responses, we did evaluate changes in expression of intracellular IFN-␥ (Th1 cytokine) and IL-10 (Th2 cytokine), both of which are produced in response to specific recall antigens.…”

Membrane markers of the immune cells in swine: an update

“…CD4/CD8 double-positive (DP) lymphocytes were found to increase gradually in proportion with age (30-55% by 3 years of age) and were able to proliferate in response to stimulation with recall viral antigen consistent with the hypothesis that this population in swine includes memory/effector T cells [52,173,177,248,249] [152]. Accordingly, after mitogen activation CD4 + 2E3 + T cells express high levels of IL-2 mRNA, but only traces of IFN-or IL-4 mRNA.…”

“…MAb anti-CD45 (or leukocyte common antigen) were based on their broad reactivity patterns with lymphoid and myeloid cells and their ability to immunoprecipitate three polypeptides with an apparent MW of 226, 210 and 190 kDa whereas mAb anti-CD45R were based on their restricted reactivity against lymphoid and myeloid target cells, and their ability to immunoprecipitate either two polypeptides with an apparent molecular weight of 226 and 210 kDa or a single polypeptide with an apparent molecular weight of 210 kDa [52,247].…”