Isotypes: pgs 18-20 Flashcards
How many subclasses of IgG are there?
4 (IgG1, IgG2, IgG3, and IgG4)
Which IgGs cross the placenta?
IgG3, IgG1, and IgG4
What is the order of most to least effective complement activators?
IgG3 (most), IgG1, IgG2 (inefficient), IgG4 (doesn’t activate complement at all)
What percentage of IgG makes up the total serum immunoglobulin?
80%
What percentage of IgG in serum represents the total serum protein?
15%
What is the molecular weight of IgG?
150,000 Da
What is the distribution of IgG intravascular and extravascular?
Equal concentrations/distributions
IgG (except IgG3) has a half life of ______ days.
23 days (3 weeks)
Which immunoglobulin has the longest half life of all the isotypes?
IgG
What is the half life of IgG3?
7 days
T/F - IgG can caust multivalent, particulate antigens to precipitate, and may cause microorganisms to clump or agglutinate.
True
IgG can bind to the surface of invading cells. After binding, certain effector cells (NK cells, macrophages, and eosinophils) of the immune system can bind to the IgG and kill the invading cell. What is this process known as?
Antibody-dependent cell-mediated cytotoxicity (ADCC)
How does IgG affect toxins/viruses?
It can bind to the binding site of the toxin or virus, thereby blocking the interaction between toxin/virus, so the viral replicative cycle and toxin affect cannot occur.
Can IgG interact with flagella?
Yes, it can bind to the flagella or cilia of the microbe and interfere with the microbe’s ability to locomote. This doesn’t kill the organism, but limits the ability to spread.
What percentage of the serum immunoglobulin is made up of IgM?
5-10%
IgM is a _________ (shape).
Pentamer
The _____ chain helps in polymerization and enables IgM to be secreted into bodily fluids.
J
IgM is ___ to _____ times more efficient at agglutination than IgG.
100-1,000 times more efficient
Out of all the immunoglobulins, which ones is most efficient as a complement fixer?
IgM
Can IgM leave the vasculature readily?
No, because it is 900,000 Da. Yet, it is still found in secretions.
What is the major secretory antibody?
IgA
IgA makes up _____ of serum immunoglobulin.
10-15%
In serum, IgA exists as a _________ and secretory IgA is a dimer or tetramer.
monomer
What immunoglobulin is produced more daily than any other antibody isotype combined?
IgA (There is ~3,600 to 9,100 mg)
Serum IgA may participate in phagocytosis and release of inflammatory mediators and has a half-life of ____ days.
5.5 days
Most IgA is secreted. What is it secreted into?
Tears, colostrum, sweat, mucus, and saliva
How does IgA obtain the S component?
When IgA is transported into the epithelial cell via receptor-mediated endocytosis and transpoted to the luminal side of the cell. During this process an additional peptide chain is added (the S chain). It is thought that the S chain increases the half life of the secretory IgA by retarding degradation
T/F - IgA neutralizes viruses and is more effective as an agglutinating antibody than IgG.
True
IgA is bactericidal against Gram __(+/-)__ organisms in the presence of lysozyme.
gram negative
In humans IgA functions to protect what?
The upper respiratory tract
