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Thread: Q-1 Immuno

  1. #1
    Roxanita is offline Senior Member
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    Q-1 Immuno

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    Q1) Which of the following best defines a hapten?

    a) A substance that binds to a specific site on the Fab fragments of antibodies
    b) Any substance that can evoke an immune response
    c) Any substance that is able to combine with T or B cells
    d) A simple substance that is not immunogenic itself but can react with a specific antibody
    e) Any protein or carbohydrate that enters the body

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    kokushubila is offline Junior Member
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    Haptens

    Answer d)

    A hapten is a molecule that is not immunogenic by itself but can react with specific antibodies.
    Haptens are usually small molecules but some are high molecular weight nucleic acids.
    Examples of haptens are Drugs eg Penicillins, Poison oak, poison ivy.

    Haptens are not immunogenic because they can not activate helper T cells due to inability to bind to MHC proteins(not polypeptides,only polypeptides do so)
    Furthermore the haptens are univalent and therefore can not activate B cells by themselves.
    They can stimulate responce by binding to a carrier protein, Interact with an IGM receptor on B cell and internalised ready for presentation to helper T cell.

    Anymore clarification?

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