Exam II - Antibodies Flashcards
Which types of cells produce antibodies?
Plasma cells
What type of globulins are Ab?
Gamma globulins
During which phase of the immune response are Ab produced?
recognition phase and effector phase
What class of Ab has the least carbohydrate?
IgG
How many heavy & light chains make up an Ab?
one heavy chain, one light chain
How many C and V regions does the light chain possess?
1 C region, 1 V region
How many C & V regions does the heavy chain possess?
3 C region, 1 V region
Where is the hinge region located?
On the heavy chain between the CH1 and CH2 regions
Which Abs do not possess hinge regions?
IgM and IgE
What is the bifunctional nature of Ab?
Antigen recognition and effector functions are spatially separate from each other
Where does papain cleave an Ab?
Which fragments remain?
Papain cleaves IgG above the -S-S bond at the hinge region
2 Fab segments and 1 Fc segment
Where does pepsin cleave an Ab?
Which fragments remain?
Pepsin cleaves below the -S-S bond at the hinge region, so the interchain disulfide bonds are retained in the F(ab’)2 molecule, though the Fc fragment is degraded
Define hypervariable region
the hypervariable regions are sites within the V light and heavy regoins where the amino acid sequences are highly variable
hypervariable regions are also known as:
Complementarity-determining regions (CDR)
Which CDR is the most variable?
CDR3 of the variable regions on heavy & light chains
What is Ag-Ab binding characterized by?
non-covalent, reversible binding
Define avidity
the strength of the binding between one Fab fragment of Ab and an epitope of an antigen
Which Ab class demonstrates the highest Avidity?
IgM (pentameric)
When can Ab act as Ags ?
What are they called in this situation?
When they’re introduced to a foreign host
Anti-antibodies
Define isotype
refers to the antigenic differences in the C and Ch regions
Define allotype
additional antigenic features of Cl and Ch regions that vary among individuals (establish paternity)
Define idiotype
antigenic determinants formed by the amino acids in the hypervariable regions
What is the primary function of an Ab?
to bind to an antigen
Where and when is IgG found primarily?
found in blood, tissue spaces, and extravascular spaces. It is found in response to the secondary immune response and is the major Ig in serum
List the 3 FcγRs
FcγRI, FcγRII, FcγRIII
Can IgG cross the placenta?
Yes, but not in all species
List 2 of the effector functions of IgG
opsonization and neutralizatoin via complement activation
Why is IgM the most efficient Ig in agglutination and complement activation?
because it has the most Fabs, and has the highest avidity
Where in the body is IgM found?
serum
What is elevated IgM in the neonate blood indicative of?
transplacental infection
In what form is sIgA found?
dimeric form
Where does IgA acquire it secretory component?
It is synthesized by epithelial cells
What are the functions of sIgA?
protection of mucous membranes
To what does the Fc portion of IgG bind?
To receptors on the placenta, lymphocytes
Which Ab are heat liable?
IgE & IgD
IgE is predominantly associated in immune response to which two things?
Allergic reactions and parasitic infections
What is the function of IgD?
Antigen receptor along with IgM on naive B cells
Which cells can express IgD?
naive B cells
What types of Ab results from Ag injection into an animal?
polyclonal antibodies
What do we call Ab that arise from a single clone cell?
monoclonal antibodies
Which two cell types are fused together for the production of monoclonal Ab?
myeloma cell and a normal B cell
______________ is the only function of Igs mediated exclusively by Fab binding of antigen and does not require participation of the CH regions
neutralization is the only function of Igs mediated exclusively by Fab binding of antigen and does not require participation of the CH regions
Which Fcγ receptor is found on B cells?
FcγRII (CD32)
