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Innate Immunity

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  • Innate Immunity

    Sometimes the Innate immunity is referred to as Non-specific immunity, however, it is not completely true, it is better to be called Innate Immunity, Why?
    Because The innate Immunity realy has some sort of specificity; there are what is called Toll-like receptors TLRs that present on certain cells of innate immunity, these receptor can recognize broad structural motifs that are generally not present in the host but found on microbial surfaces eg:
    TLR1 present on monocytes, denderetic cells & macrophage: recognize lipoproteins on bacterial cells
    TLR2 on the same cells recognize peptidoglycan of G+ve bacteria, zymosan of fungi
    TLR3 on denderitic dells & B lymph: recognize viral ds DNA
    TLR4: on monocytes, denderetic cells & macrophage: recognize lipopolysaccharide of G-ve bacteria
    TLR5 on the same cells :recognize flagellin protein of bacteria
    TLR6: recognize polypeptides of mycoplasma
    As we see the innate system shows cetain limits of specificity.
    Another feature which is attractive, the innate immunity can discriminate self from non self; The natural killer lymphocyte - amajor player in innate immunity- carries 2 types of receptors: Killer activation receptors KAR & killer inhibition receptors KIR; the KIR recognize self MHC molecules on host cells and so prevent NK from attacking self cells. Foreign cells not express self MHC and so the KAR will be activated to kill them
    " و هكذا بعض الأشياء التي نضحك منها في ارتياح
    لأن أعيننا لا تراها كاملة"
    شاعر ألماني
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