The kinetics of cytokine production and CD25 expression by porcine lymphocyte subpopulations following exposure to classical swine fever virus (CSFV).
Surface expression of IL-2R-alpha (CD25) is widely used to identify activated lymphocyte populations, while interferon-gamma (IFN-gamma) levels have been shown to be a good indicator of cell-mediated immunity (CMI) in pigs. To investigate the relationship between these two parameters, we developed an intracellular cytokine-staining assay and studied the kinetics of cytokine (IFN-gamma and interleukin-10, IL-10) production relative to CD25 expression in porcine lymphocyte subpopulations, following immunization with a classical swine fever (CSF) vaccine. The number of activated memory T cells (CD4(+)CD8(+)CD25(+) cells) increased slightly in the peripheral blood mononuclear cell (PBMC) population soon after vaccination, then diminished within a few weeks. The number of activated cytotoxic T cells (CD4(-)CD8(+)CD25(+) cells) peaked approximately 2 weeks after the memory population. Although the number of IFN-gamma producing cells detected in this experiment was relatively low, the CD4(+)CD8(+) T cells were major IFN-gamma producers in the PBMCs throughout the experiment. In another experiment, CSF-vaccinated pigs were challenged with a virulent classical swine fever virus (CSFV), and the kinetics of CD25 expression and cytokine productions were monitored. Following exposure to the virus, the number of IFN-gamma producing cells in the PBMCs increased markedly in both the vaccinated and unvaccinated groups. The CD4(-)CD8(+) cells were major IFN-gamma producing cells in vaccinated pigs, while both CD4(+)CD8(+) and CD4(-)CD8(+) populations contributed to the IFN-gamma production in the control group. Interestingly, the enhanced IFN-gamma production was not associated with the upregulation of CD25 expression following the CSFV challenge. In addition, exposure to the virulent CSFV significantly increased interleukin-10 production by the CD4(-)CD8(+) populations in PBMCs of the unvaccinated pigs. Taken together, our results indicated that CD25 expression and IFN-gamma production were not tightly associated in porcine lymphocytes. In addition, the CD4(-)CD8(+) lymphocytes of the PBMCs played a major role in cytokine productions following the CSFV challenge.
Suradhat
S
S
Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd., Pathumwan, Bangkok 10330, Thailand. sanipa.s@chula.ac.th
Sada
W
W
Buranapraditkun
S
S
Damrongwatanapokin
S
S
D000818:Animals; D000956:Antigens, Viral / Q000008:administration & dosage; D006691:Classical Swine Fever / Q000276:immunology; D006692:Classical Swine Fever Virus / Q000276:immunology / Q000472:pathogenicity*; D016207:Cytokines / Q000096:biosynthesis*; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D007700:Kinetics; D016131:Lymphocyte Subsets / Q000276:immunology*; D015375:Receptors, Interleukin-2 / Q000378:metabolism*; D034421:Sus scrofa; D014765:Viral Vaccines / Q000008:administration & dosage
D000956:Antigens, Viral; D016207:Cytokines; D015375:Receptors, Interleukin-2; D014765:Viral Vaccines; D016753:Interleukin-10; D007371:Interferon-gamma