Page 586 - Veterinary Immunology, 10th Edition
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VetBooks.ir  Innate Cytotoxic Cells





               Natural Killer Cells


               The first ILCs identified were called natural killer (NK) cells
               because they were able to kill virus-infected and tumor cells
               without requiring prior activation. NK cells can be considered to be

               cytotoxic ILC1s. In most mammals, NK cells are large, granular
               lymphocytes. In cattle, NK cells are large cells, but may not contain
               large cytoplasmic granules (Fig. 19.5). There is debate about NK cell
               morphology in the pig. Some investigators claim that they are large
               granular lymphocytes, whereas others believe that they are small

               lymphocytes without obvious cytoplasmic granules.



























                           FIG. 19.5  A transmission electron micrograph of a human NK cell.
                             The nucleus is indented and rich in chromatic. The cytoplasm is
                             abundant and contains many granules. Numerous mitochondria,
                            centrioles, and a Golgi are visible. Original magnification ×17,000.
                            (From Carpen O, Virtanen I, Saksela E: Ultrastructure of human natural killer cells:
                           nature of the cytolytic contacts in relation to cellular secretion, J Immunol 128:2691,
                                                         1982.)





               Origins and Location


               NK cells are produced by bone marrow stem cells and are found in
               peripheral blood, lymph nodes, spleen, and bone marrow but not in
               the thymus. They range from 2% of the lymphocytes in mouse






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