Porcine T lymphocytes and NK cells – An update

Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
Developmental and comparative immunology (Impact Factor: 2.82). 08/2008; 33(3):310-20. DOI: 10.1016/j.dci.2008.06.003
Source: PubMed


Natural killer (NK) cells represent an important cell population of the innate immune system with the ability to attack spontaneously pathogen-infected and malignant body cells as well as to produce immune-regulatory cytokines. T lymphocytes belong to the adaptive immune system and perform a wide array of functions in immune regulation, inflammation and protective immune responses. In this review we summarize the current knowledge about the phenotype and functional characteristics of these two cell populations in swine.

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Available from: Armin Saalmueller, Jul 23, 2014
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    • "CD4+ T cells represent T helper cells that aid in the humoral immune response and are responsible for Th2 cytokine production . CD8+ T cells represent cytotoxic T cells that are important in killing virus infected cells (Germain, 2002; Gerner et al., 2009). The CD3+CD4+ T cell frequency was higher in the uninfected suckling pigs compared to uninfected weaned pigs, whereas infected suckling pigs had transient relative leukopenia at PID 1 and then had increased CD3+CD4+ T cell frequencies at PID 5 compared to uninfected suckling pigs. "
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    ABSTRACT: Porcine epidemic diarrhea (PED) is an enteric coronaviral infection that causes severe morbidity and mortality in suckling pigs, but less severe disease in older pigs. Consequently, it causes significant economic losses to the pork industry. There are limited studies on the innate immune responses to PED virus (PEDV) in pigs. The aims of our study were to investigate differences in innate immune responses to PEDV infection in suckling and weaned pigs and to examine if disease severity coincides with reduced innate immune responses. Weaned 26-day-old pigs (n = 20) and 9-day-old nursing pigs (n = 20) were assigned to PEDV inoculated or uninoculated control groups. The pigs were observed daily for clinical signs, virus shedding and were euthanized at post-inoculation days (PIDs) 1 and 5 to assay immune responses. Blood samples were collected at PIDs 1, 3 and 5. The natural killer (NK) cell frequencies, NK cell activities (lysis of target K562 tumor cells in vitro), CD3+CD4+ T cell and CD3+CD8+ T cell frequencies were measured in blood and ileum at PIDs 1 and 5. The PEDV infected suckling pigs showed severe diarrhea and vomiting at PID 1, whereas the PEDV infected weaned pigs showed milder clinical signs starting at PID 3. PEDV infected suckling pigs had significantly higher diarrhea scores, earlier fecal PEDV RNA shedding and significantly higher viremia (viral RNA in serum) compared to weaned pigs. There was no mortality in either infected suckling or infected weaned pigs. The control pigs not inoculated with PEDV did not show any clinical signs and no detectable fecal or serum PEDV RNA. Strikingly, PEDV infected suckling pigs had significantly lower NK cell frequencies, undetectable NK cell activity and lower IFN producing NK cells in blood and ileum compared to PEDV infected weaned pigs. Pro-inflammatory cytokine profiles of PEDV infected suckling pigs differed from those of PEDV infected weaned pigs and coincided with onset of fecal PEDV RNA shedding and serum PEDV RNA titers. The infected suckling pigs have higher and earlier increases in serum IFN, but lower serum IL-8 and TNF levels compared to infected weaned pigs. CD3+CD4+ T cell frequencies were significantly higher in ileum of suckling pigs than in weaned pigs, whereas there was no difference in CD3+CD8+ T cell frequencies. In conclusion, the observations of impaired lytic activity and IFN-production by NK cells in suckling pigs coincided with the increased severity of PEDV infection in the suckling pigs compared with the weaned pigs.
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    • "NK cells in swine blood are identified as CD3−CD8α+ cells [21], and a recent study has found that only about half of the NK cell population in the blood of swine express NKp46 [22]. NKp46− NK cells show a similar ability to kill target cells but produce less IFN-γ as compared to NKp46+ NK cells. "
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    ABSTRACT: Natural killer (NK) cells are important players in the innate immune response against influenza A virus and the activating receptor NKp46, which binds hemagglutinin on the surface of infected cells, has been assigned a role in this context. As pigs are natural hosts for influenza A viruses and pigs possess both NKp46- and NKp46+ NK cells, they represent a good animal model for studying the role of the NKp46 receptor during influenza. We explored the role of NK cells in piglets experimentally infected with 2009 pandemic H1N1 influenza virus by flow cytometric analyses of cells isolated from blood and lung tissue and by immunostaining of lung tissue sections. The number of NKp46+ NK cells was reduced while NKp46- NK cells remained unaltered in the blood 1-3 days after infection. In the lungs, the intensity of NKp46 expression on NK cells was increased during the first 3 days, and areas where influenza virus nucleoprotein was detected were associated with increased numbers of NKp46+ NK cells when compared to uninfected areas. NKp46+ NK cells in the lung were neither found to be infected with influenza virus nor to be undergoing apoptosis. The binding of porcine NKp46 to influenza virus infected cells was verified in an in vitro assay. These data support the involvement of porcine NKp46+ NK cells in the local immune response against influenza virus.
    PLoS ONE 06/2014; 9(6):e100619. DOI:10.1371/journal.pone.0100619 · 3.23 Impact Factor
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    • "The analysis was performed using an Epics® XL-MCL cytometer (Beckman-Coulter, Indianapolis, IN, USA) based on PBMC gating after acquisition of at least 10 000 cell events and cell subsets were evaluated based on previous reports. The absolute cell levels (cells/μL) were determined based on the absolute leukocyte counts and lymphocyte percentages [37-40]. "
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    ABSTRACT: Porcine circovirus type 2 (PCV2) vaccination represents an important measure to cope with PCV2 infection; however, data regarding the modulation of the immune cell compartment are still limited, especially under field conditions. This study is aimed at investigating the features of the cellular immune response in conventional piglets induced by vaccination using a capsid (Cap) protein-based PCV2 vaccine compared to unvaccinated animals when exposed to PCV2 natural infection. Immune reactivity was evaluated by quantifying peripheral cell subsets involved in the anti-viral response and characterizing the interferon-gamma (IFN-gamma) secreting cell (SC) responsiveness both in vivo and upon in vitro whole PCV2 recall. The vaccination triggered an early and intense IFN-gamma secreting cell response and induced the activation of peripheral lymphocytes. The early increase of IFN-gamma SC frequencies resulted in a remarkable and transient tendency to increased IFN-gamma productivity in vaccinated pigs. In vaccinated animals, soon before the onset of infection occurring 15-16 weeks post-vaccination, the recalled PCV2-specific immune response was characterized by moderate PCV2-specific IFN-gamma secreting cell frequencies and augmented productivity together with reactive CD4+CD8+ memory T cells. Conversely, upon infection, unvaccinated animals showed very high frequencies of IFN-gamma secreting cells and a tendency to lower productivity, which paralleled with effector CD4-CD8+ cytotoxic cell responsiveness. The study shows that PCV2 vaccination induces a long-lasting immunity sustained by memory T cells and IFN-gamma secreting cells that potentially played a role in preventing the onset of infection; the extent and duration of this reactivity can be an important feature for evaluating the protective immunity induced by vaccination.
    Veterinary Research 04/2014; 45(1):44. DOI:10.1186/1297-9716-45-44 · 2.82 Impact Factor
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