Antibody Classes: IgG • ~80% of total serum Ab • 2γ H chains + 2 κ or 2λ L chains • 4 subclasses due to variation in γ chain aa seq • Variation affects bio activity • #’d according to prevalence (IgG1>IgG2>IgG3>IgG4) • IgG1,3,4 readily cross placenta • 3 effective complement activator • 1,3 bind effectively to Fc receptor on phago cells
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Antibody Classes: IgG ~80% of total serum Ab 2γ H chains + 2 κ or 2λ L chains 4 subclasses due to variation in γ chain aa seq Variation affects bio activity.
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Antibody Classes: IgG
• ~80% of total serum Ab
• 2γ H chains + 2 κ or 2λ L chains
• 4 subclasses due to variation in γ chain aa seq
• Variation affects bio activity
• #’d according to prevalence
(IgG1>IgG2>IgG3>IgG4)
• IgG1,3,4 readily cross placenta
• 3 effective complement activator
• 1,3 bind effectively to Fc receptor on phago cells
Antibody Classes: IgA
• 10-15% of total serum Ab; predom in secretions
• Monmeric form in blood• Di/tri/tetrameric forms in
secretions (sIgA)• “secretory component” of
epith cells aids in uptake/release to surfaces
• Daily prod of IgA > than any other class (5-15 g/day) in mucus
Antibody Classes: IgA
IgA plasma cells
“home” to subepith
tissue release IgA
which binds to poly-Ig
receptor endocytosis
cleavage of receptor
to become “secretory
component” for sIgA
*Important effector
function! at these
locations
Antibody Classes: IgM
• 5-10% of total serum Ab• Monomeric IgM as mIgM on
B cells• Pentameric IgM is secreted
(sIgM)• Joined by J chain of
glycoprotein• 1st Ig class of 1° IR• Most efficient at Ag-binding• Most efficient at complement