IgE, Mast Cells and Eosinophils

by Peter Delves, PhD

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    So what is IgE in terms of its relationship to human disease normally, and where do we find it and how much of it do we have? Well, out of the five different classes of antibody, it’s the one that usually is present in the serum at the lowest concentration. And in fact we only have about 100ng/ml of circulating IgE. Contrast this with IgG where the concentration is 15mg/ml. So really, incredibly small amounts of IgE in the circulation. In fact it doesn’t last very long at all in the circulation. It has a half life of around about two and a half days. However once it becomes bound to that high affinity FcεR1 on the surface of mast cells, it is stabilized from being degraded and it then has a half life of around about 12 weeks. It is part of normal physiological protective responses. So you find IgE elevated in certain parasitic diseases, for example schistosomiasis. You find it in an abnormal pathological situation, such as the hyper-IgE syndrome, which is a primary immunodeficiency where is there-- where there is defective production of gamma interferon, and therefore there is an increased level of interleukin-4, because remember Th1 cells that produce gamma interferon down-regulate the activity of Th2 cells that produce IL-4. So in the absence of gamma interferon production, there’ll be increased Th2 activity and therefore increased production of the cytokine interleukin-4. And of course we also find elevated levels of IgE in allergy which is what we’re discussing at this moment. Class switching to IgE is promoted by the cytokines interleukin-4 and interleukin-13 which come from Th2 cells, and as I’ve already mentioned, is inhibited by gamma interferon produced by Th1 cells. Let’s have a look at how mast cells become activated. The IgE is coating...

    About the Lecture

    The lecture IgE, Mast Cells and Eosinophils by Peter Delves, PhD is from the course Hypersensitivity and Autoimmune Disease.

    Author of lecture IgE, Mast Cells and Eosinophils

     Peter Delves, PhD

    Peter Delves, PhD

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