HTHSCI 1DT3 Lecture 3: Immunology_Lec3_Natural Killer Cells
4 Mar 2016
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Innate immune system (nk cells: functions in body, how to use in treatment (viral infection, cancer) Natural killer (which are lymphocytes) cells circulate through body, looking for target (bad, virally infected, tumour) cells. Bigger than b cells and t cells, but smaller than macrophages. Naturally have ability to kill target cells without experience, memory, education, prior exposure, unlike t cells. (spontaneously kill tumour or vitally infected cells) 2 important sets: activatory receptors: receive activatory (positive) signals sent to nk cells, activate nk cells, inhibitory: send negative signal to nk cells. Every nucleated cell, express mhc class i : send potent negative signal (when body cell), if cells lose expression of mhc class i, no inhibitory signal given to nk cells. If in this circumstance, get activatory signal, will start killing, regardless of body (autoimmunity problems) or pathogen. No, balance between positive (activatory) and negative (inhibitory) signal, if one is dominant, will then follow that.
