Flashcards in Immunoglobulin structure Deck (45):
Predominant antibody in the secondary immune response
Predominant antibody in external secretions
Predominant antibody in primary response
Found mainly on the surface of B cells
Involvement in allergic hypersensitivities
Common core structure of all antibodies
Two identical light chains and two identical heavy chains, where each light chain is attached to a heavy chain and the heavy chains are attached to each other
Where all the chains, each of about 110 amino acids in length, all fold independently
Isotypes of light chain
Either kappa or lambda
N-terminal region of the heavy and light chains
Variable regions; the rest of them are all constant regions
Combination of the heavy chain variable and light chain variable regions make up the antigen binding region
Carries out other effector functions of the antibody (crossing the placenta, sites for attachment of Fc receptor, complement binding)
Complementarity determining regions - three sites on the variable region above all else determine what will bind
How are the CDRs exposed?
When they fold, the portions of the CDR in the amino acid sequence stick out as projecting loops
How is IgM secreted?
In its pentameric form, with a molecular weight of 900,000 daltons
What joins the subunits of IgM?
The J chain
IgM is the primary antibody for antigen administered __
IgM is also the primary antibody elicited by __
How is IgM expressed on B cells?
As a monomer
Can IgM cross the placenta?
Approximate serum concentration of IgM
IgG is the antibody most characteristic for ___
What is the difference in structure between IgG's secreted and membrane form?
Nothing significant; both monomeric, both ~150,000 daltons
How does IgG recruit complement fixation?
Varies based on subclass
Can IgG cross the placenta?
Yes, due to presence of FcRn
Approximate serum concentration of IgG
Typical form of IgD
Function of IgD
B cell antigen receptor along with IgM
Serum concentration of IgD
To what types of cells does IgE bind?
Mast cells and basophils due to Fc receptor
How is IgE secreted?
As a CHO-rich monomer of 190,000 daltons
Serum concentration of IgE
How does predominant IgA occur?
As a dimer
How are the subunits of IgA joined?
By the J chain
How does serum IgA occur?
As a monomer (function is unclear)
Can IgA cross the placenta?
How does it fix complement?
Through alternative pathway
Serum concentration of IgA
IgA plays a crucial role in __
How do antibodies contribute to the immune response?
By binding to and neutralizing pathogens, as well as signalling for destruction by other cells
Fc-receptor mediated killing
If antibodies don't neutralize the pathogen, the Fcs on the antibodies will signal to FcRs on macrophages, eosinophils, NK cells, basophils, and mast cells, and they'll kill it
Neonatal antibody production
IgG: maternal IgG for the first few months, then reaches adult levels at age 4
IgM: adult levels reached at age 10 months
IgA: adult levels reach at 10 years old
Clinical use of immunoglobulins: polyclonal and monoclonal antibodies
Polyclonal is found in immunized individuals. Monoclonal can be used in vitro to keep passive antibodies
Examples of polyclonal antibody uses
IVIG treatment for inflammatory diseases
Examples of monoclonal antibody therapy
Tumor-specific antibodies to treat cancer