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What are the characteristics of IgG?
- Most abundant
- Single 4 polypeptide structure
- MW 150000
- 4 subclasses
- Found in serum and tissue
- Half life=21 d
- Fx=Opsonizations, complement (not IgG4), crosses placenta
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What are the characteristics of IgA?
- Secretory Ig
- Basic 4 polypeptide strucutre
- MW 160000
- 2 subclasses=monomer (found in serum) and dimer (found in secretions)
- J chain (formed by B cell) connects dimer
- Has secretory piece involved in transport
- DOES NOT cross placenta
- DOES NOT fix complement by classical pathway
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What are the chracteristics of IgM?
- 2 subclasses=monomer (surface of B cell, serves as BCR for Ag) and pentamer (in circulation)
- MW=900000 (Largest Ig)
- 1st made in response to Ag
- Found exclusively in serum
- DOESNT cross placenta
- Great at complement fixation
- Not good at opsonization
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What are the characteristics of IgD?
- MW 185000
- Also found on surface of B cell (acts as a BCR for Ag)
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What are the characteristics of IgE?
- Smallest Ig
- MW 200000
- Attaches to Mast Cell surface
- Short half life expect when on MC
- Impt in allergic and parasitic rxns
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