Innate Immunity: The Natural Killer Cells

by Richard Mitchell, MD, PhD

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    00:01 Let's look at the natural killer cell.

    00:03 The previous talk, I again, like in these to a deranged person with an AK-47.

    00:09 If natural killer cells don't see an appropriate self-antigen, a friendly face, they will fire.

    00:18 So, why do we have NK cells? Well, they are important for immunity to intracellular pathogens.

    00:27 And we have an example here of a virus infected cell at the bottom that is no longer expressing inhibitory receptors.

    00:37 The loss of those inhibitory receptors, because of the viral infection will cause the natural killer cell to sidle up next to that cell and to kill it.

    00:45 Natural killer cells also have on their surface Fc receptors.

    00:48 So they recognize the constant fret constant region fragment of bound antibody.

    00:55 And so, if antibody is bound to a particular target, they will come up bind with their Fc receptors and kill, this is called antibody-dependent cell mediated cytotoxicity or ADCC as you see on the screen there, They kill just like a cytotoxic T cell.

    01:11 So they have within them preformed granules that contain porphyrin, which is a pore-forming protein, and granzymes, which will activate the intrinsic apoptosis pathways.

    01:24 So when they form their synapse, when they bind, either through Fc receptor and an antibody recognition, or through that loss of the inhibitory receptors.

    01:34 They will release porphyrin in a directorial fashion, punch a hole, and then granzyme will go across and will cause the death of the target cell.

    01:45 That natural killer cells also make cytokines.

    01:50 So they are going to be important for driving the stimulation of other cells.

    01:55 This is all kind of trying to recruit a big inflammatory army that can deal with potential infections.

    02:01 So here we see a macrophage talking to an NK cell, the macrophage is going to make Interleukin-12 that's IL-12, that will activate the NK cell and make it a more robust responding cell.

    02:14 At the same time, that NK cell is going to make interferon gamma which will drive the activation of the interferon gamma macrophages and make them better at their job.

    About the Lecture

    The lecture Innate Immunity: The Natural Killer Cells by Richard Mitchell, MD, PhD is from the course Immune-mediated Diseases.

    Included Quiz Questions

    1. Perforin and granzymes
    2. Histamine and serotonin
    3. Leukotrienes
    4. IL-12
    5. Interferon-gamma

    Author of lecture Innate Immunity: The Natural Killer Cells

     Richard Mitchell, MD, PhD

    Richard Mitchell, MD, PhD

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