IgGs are the most numerous antibody in the circulation and they can cross the placenta. They activate complement(except IgG4) and enhance phagocytosis through opsonisation.
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How does IgG cross the placenta?
Active process using the FcRn recpetor.
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What does IgA do?
IgA 1&2 protet mucosal surfaces.
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How is IgA released at mucosal surfaces?
They are released by the Poly Ig receptor on mucosal surfaces. It releases the dimeric IgA thorugh excytosis and adds the secretory place which protects the antibody from digestion by enzymes.
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What does IgM do?
IgM is the first antibody to be produced in immulogical development and in the primary immune response. It has powerful agglutination adn complement processes. It is BCR on naive B cells. It shows no immunological memory.
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What form is IgM in?
BCR on naive B cells and secreted as a pentamer.
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What does IgD do?
IgD is a BCR on naive B cells where it is coexpressed with IgM.
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What does IgE do?
IgE is important in the inflammatory response through recruitment of Eosinophils. It binds to receptors on mast cells and basophils sensitising them to release inflamatory chemicals and therefore mediating Type I hypersensitivity reactions.
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What do mast cells and basophils release?
Inflammatory mediators from within the cell include histamine and heparin(a proteoglycan). It syntehesises new cytokines t be released at the time as well.
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What is clonal selection?
b cells are selected by specific antigen in lymphoid tissues. Most are T cell dependent. IgM plasma cells are produced first and then class switching occurs.
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What is class switching?
THe plasma cells are initially IgM producing and under the influence of different cytokines they can switch to IgE IgA and IgG production.
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What is the role of a germinal center?
Naive B cells differentiate and prolifereate, they undergo somatic hypermutation and class switching.
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What are affinity and avidity?
Affinity is the strength of the antibody-antigen reaction. Avidity is binding to multiple antigens simultaneously but transiently.
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What chromosones are involed in antibody coding?
Chromosone 2 in Kappa genes, Chromosone 20 in Lamda genes, Chromosone14 in heavy chain genes.
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What are the regions of the Kappa and lamda genes?
The genes are spliced and recombined so that the antibodies are able to be very different and respond to multiple antigens.
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How does recombination occur?
The enezymes RAG1 and RAG2 recognise recombination signal sequences RSS12 and RSS23. This ensures that recombination can only occur ina certain order as RSS12 must be next to an RSS23 only.
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What other sources of variablitly are present in both TCR and BCR?
Recombination innacuracies as the RAG enzymes can cut at any point in the codon. N(on templated) Nuceotide addition.
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What mediates N-Nucleotide addition?
Terminal deoxynucleotidyltransferase.
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What additional variability is unique to BCR?
Somatic hypermutation as point mutations in the VDJ region. Class switch recombination by recognition of switch sequences.
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What mediates both of these aditional variablities?
AID- activation indued cytidine deaminase.
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What does genetic variability of antibodies do?
Leads to wide variability in the antibodies produced and therefore the antigens which can be targeted as well as the affinity of these antibodies.
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Other cards in this set
Card 2
Front
What do IgGs do?
Back
IgGs are the most numerous antibody in the circulation and they can cross the placenta. They activate complement(except IgG4) and enhance phagocytosis through opsonisation.
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