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THE OTHER
LYMPHOCYTES |
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NK cells present a cytotoxic activity against cells infected by viruses and tumor cells, even though they do not recognize them by a specific antigenic stimulus (NK cells do not express TcR). This cytotoxic activity is not limited by SLA, as T lymphocytes (CD 8). Their activation mechanisms begin when they recognize, in a natural way, cells that do not express SLA in a correct way, as happens with most virus infected cells. Apart from this, they secrete soluble mediators (cytokines) such as Tumor Necrosis Factor (TNF), interferon g. This allows the stimulation of various lymphoid mechanisms. (Chapter 6). |
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NK cell expressing the receptor for the Fc fraction of immunoglobulins. |
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NK cells have a role in the natural or innate immune response. These cells appear in a larger proportion in young animals, and they diminish as the animal grows. This means that the role of NK cells is related to natural or innate immune response mechanisms, and not to those mediated by a specific antigenic stimulation (acquired immunity). |
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