Natural killer (NK) cells are one of the main cellular components of the immune system. They can be characterized by two major properties: production of immune regulatory cytokines and chemokines as well as cytolytic destruction of particular target cells. Furthermore, NK cells have the capacity to respond to cytokines, another fuction, which is in swine still poorly understood.
Therefore, in this study we tested the influence of recombinant cytokines IL-2, IL-12 and IL-18 on cytolytic activity, phenotype and IFN-y production of porcine NK cells.
NK cells were enriched from PBMC using a magnetic cell separation (MACS) strategy and respective fractions were used in flow cytometry (FCM) based cytolytic assays with the humantumor cell line K562 as target. The NK cell enriched CD3 CD21 SWC3 fraction showed an evident increase in the cytolytic activity compared to PBMC.
The strong influence of recombinant cytokines IL-2, IL-12 and IL-18 on the cytolytic activity of porcine NK cells was confirmed, showing also a synergistic effect of IL-2 together with Il-12 and/or IL-18.Furthermore we confirmed and expanded our knowledge about the phenotype of resting NK cells, showing them as CD3 CD5 CD6 CD8a CD8ß CD16 perforin and demonstrated phenotypic changes occurring after cytokine stimulation; up-regulation of CD25, MHC II and an intracellular accumulation of perforin.
NK cells work / in contrast to B and T cells / trough germline encoded receptors / therefore by definition belong to the innate immune system