Functional characterization of porcine CD4+CD8+ extrathymic T lymphocytes

Cell Immunol. 1996 Mar 15;168(2):291-6. doi: 10.1006/cimm.1996.0078.


The porcine immune system is unique in that the expression of CD4 and CD8 antigens defines four subpopulations of resting, extrathymic (CD1-) T lymphocytes. In addition to CD4-CD8+ and CD4+CD8- T lymphocytes, CD4-CD8- and CD4+CD8+ lymphocyte subpopulations are prominent in blood as well as in lymphoid tissues. In the present study, a functional comparison was made between CD4+CD8- and CD4+CD8+ T lymphocyte subpopulations. In a primary in vitro immune response against alloantigenic stimulator cells, both subpopulations proliferated without significant differences in their reactivity. Different results were obtained when analyzing the antigen-specific functions of the two CD4+ subpopulations in a secondary response against recall viral antigen; these experiments were performed with T lymphocytes from pseudorabies virus-immunized pigs. The proliferative response against viral antigens could be assigned to the CD4+CD8+ subpopulation, whereas the CD4+CD8- subpopulation remained nonreactive. Further analyses of the virus-specific in vitro immune response revealed a major histocompatibility complex (MHC) class II restricted helper T lymphocyte reaction involving CD4 but not CD8 molecules as restriction elements. Taken together, these results demonstrate that only the extrathymic CD4+CD8+ T lymphocyte subpopulation of swine contains MHC class II-restricted antigen-specific memory T helper cells.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Antigens, Viral / immunology
  • CD4 Antigens*
  • CD8 Antigens*
  • Cell Division
  • Cells, Cultured
  • Flow Cytometry
  • Histocompatibility Antigens Class II / immunology
  • Immunization
  • Immunologic Memory
  • Immunophenotyping
  • Lymphocyte Activation
  • Pseudorabies / immunology
  • Swine
  • Swine, Miniature / blood
  • Swine, Miniature / immunology*
  • T-Lymphocyte Subsets / classification
  • T-Lymphocyte Subsets / immunology*
  • T-Lymphocytes, Helper-Inducer / immunology


  • Antigens, Viral
  • CD4 Antigens
  • CD8 Antigens
  • Histocompatibility Antigens Class II