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6 Cards in this Set
- Front
- Back
IgA
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10%-15% in serum, Predominant in secretory fluids e.g. tears and saliva protecting external surphaces.
exists as a monomer in serum but can exist as dimer, trimer or tetramer. Secratory IgA exists as dimer or tetramer, linked by a J chain which aids in binding to receptor. part of receptor remains bound, thought to protect from bacterial proteases. |
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IgM Features
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First class of Ig to appear on developing B cells (monomeric) and secreted into blood for early stages of primary immune response (pentameric).
Most effective Ig for activating compliment. Efficent agglutinating and cytolytic agent . fights microbial infection in blood |
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IgM Structure
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Has an extra Constant heavy domain and exists in either monomeric or pentameric. held together by J-hcain and disulphide bonds. J-chain allows binding to secretory cells. 10 antigen binding sites but only acces to 5.
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IgD
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0.2% in serum.
Hinge region is extended More suseptable to proteolytic degradation Found on surphace of B lymphocytes Regulation of lymphocyte activation and suppression possibly in self tollerance stage |
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IgE
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Very low concentration in blood and has extra C region on heavy chain. High affinity for receptors on mast cells which mediates hypersensitivity reactions responsible for symptoms such as hayfever and asthma.
receptors on mast cells bind to IgE complex to realese histamine, resulting in vasopermeability. Also releases factors that attract eosinophils. |
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IgG
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Most abundant Ig in serum (12mg/ml, 80%)
4 human subclasses of IgG due to slightly different aa sequence in constant heavy region IgG1-4 High affinity for antigen neutralises bacterial toxin, binds to microorganisms, inactivates viruses |