1What is the main difference between innate and adaptive antigen recognition?
Innate immunity recognizes broadly conserved motifs; adaptive immunity recognizes highly diverse specific epitopes.
22 universal rules of immunology
1. Nothing happens without a receptor-ligand interaction
2. If something happens, it’s usually mediated by cytokines and chemokines

3What receptors recognize antigens in adaptive immunity?
B-cell receptors (BCRs) and T-cell receptors (TCRs).
4How are adaptive immune receptors distributed among lymphocytes?
Clonally; each lymphocyte has its own receptor specificity.
5What are the basic structural components of an immunoglobulin?
Two identical heavy chains, two identical light chains, and a hinge region.

6What does the variable region of an immunoglobulin do?
Forms the antigen-binding site and determines epitope specificity.

7What does the constant region of an immunoglobulin determine?
The antibody’s function, not its antigen specificity.

8What does the Fab region of an antibody do?
Binds antigen.
9What does the Fc region of an antibody do?
Interacts with Fc receptors on other cells to carry out antibody functions.
10Hinge regions provide what for IgG, IgA, not in IgM, IgE
conveys flexibility
11Isotopes IgA form what and IgM form what? (2)
dimers (IgA) and pentamers (IgM)
12Which immunoglobulin is the first to appear after infection?
IgM.
13Which immunoglobulin is most abundant and long-lasting in blood?
IgG.
14Which immunoglobulin is associated with allergic reactions and parasites?
IgE.
15Which immunoglobulin is secreted at mucosal barriers?
IgA.
16What types of antigens can B cells directly recognize? (4)
Proteins, lipids, carbohydrates, and nucleic acids (DNA)
17What is a linear epitope?
A continuous stretch of amino acids recognized by a BCR or antibody.

18What is a conformational or discontinuous epitope?
Amino acids brought together by protein folding or assembly.

19What happens to a discontinuous epitope if the protein loses its normal 3D structure?
The epitope can be lost.
20What are hypervariable regions (HVs) also called? What is the function of the CDRs?
1. Complementarity-determining regions (CDR1, CDR2, and CDR3).
2. They contain amino acids that interact directly with the epitope.
21How many antibody specificities does an individual B cell produce?
One.
22When is the initial diversity of B-cell receptors generated?
During B-cell development before antigen exposure.
23What two processes create initial BCR diversity?
Random gene-segment recombination and random nucleotide addition.

24Where does initial BCR diversity develop?
In the bone marrow.
25What is somatic or V(D)J recombination?
DNA-level rearrangement of Ig gene segments that creates unique BCRs.
26Which gene segments rearrange to form the immunoglobulin heavy chain?
V, D, and J segments.
- has greater diversity
27Which gene segments rearrange to form the immunoglobulin light chain?
V and J segments.
28Does V(D)J recombination occur at the DNA or RNA level?
DNA level.
29Why does random nucleotide addition increase antibody diversity?
It creates additional unique sequences at gene-segment junctions.
30What molecules allow the BCR to transmit signals into the B cell?
Igα and Igβ.
31What is the functional B-cell receptor complex?
Membrane immunoglobulin associated with Igα and Igβ.
32What form of immunoglobulin is produced first by developing B cells?
Membrane-bound immunoglobulin.
33How can the same Ig gene produce membrane-bound and secreted antibody?
Differential mRNA processing/splicing of the heavy chain.

34Does switching from membrane-bound to secreted Ig change antigen specificity?
No; both recognize the same epitope.
35What is tested at the pre-B-cell checkpoint? EXAM
Whether the rearranged heavy chain is functional and self reactive.
36Where is the final B-cell developmental checkpoint described in this lecture?
The spleen.
37What is central tolerance?
Removal of self-reactive B cells in the bone marrow.
38What is peripheral tolerance?
Removal of self-reactive B cells in peripheral tissues such as the spleen.
39Unlike in innate immunity, B-cell receptors…
uniquely recognize a single epitope
40The ability to bind to many different types of epitopes is:
1. Due to recombination events during B-cell development
2. When random nucleotides are incorporated
41In the pre-b-cell stage, which of the following is false
- Strong signals through the BCR allow survival
- There is a surrogate light chain
- Weak signaling allows for proliferation and light chain arrangement