Test 2: Differentiation and Activation of B cells Flashcards
What is the difference in movement of B cells and T cells?
B cells don’t move after maturation. The antibody does move but B cells do not
What antibodies are in the oral cavity?
SIgA or IgA
- to limit bacteria adherence
How are B cell receptors expressed on B cells?
formed my membrane bound antibodies (Ig) and invariant membrane proteins Igalpha and Igbeta
In the structure of Ig, what is the Y shape molecule formed by?
- 2 heavy chains
- 2 light chains
exists in 2 forms: membrane bound or secreted
Where are the antigen binding sites on immunoglobulin?
on variable regions
What are the function of the constant regions of immunoglobulin?
- mediate effector function
determine isotope, bind complement, and bind Fc receptors
What is the binding site composed of?
variable domains of light and heavy chains
T/F: The binding site binds wide variety of antigens.
True!
They bind proteins, lipids, polysaccharides, and nucleic acids
Is the processed or native antigen recognized by the binding site?
the native is recognized
What is the first region cluster and the first antibody to be produced?
first C region cluster= Cu
first antibody produced= IgM
How does recombination of immunoglobulin genes work?
- random selection of segments
What is the first checkpoint of maturation of B cells?
pre-BCR
- expression of pre-BCR promote survival
What is the second checkpoint of maturation of B cells?
IgM
- signals from IgM promote survival
Positive selection of B cells occurs in the bone marrow in an antigen _____________ manner.
independent
What distinguish T cells from B cells?
selection of T cells depend on antigen recognition
Plasma cells that produce high affinity Ig….
- migrate to bone marrow or mucosal tissues
- survive for years
Do memory B cells secrete Ig? Where do they live?
- do not secrete Ig
- last a lifetime in mucosal tissues and blood
How does the secondary antibody response compare to the primary?
secondary response is quicker, larger, IgG more abundant, and high affinity
In innate immune signals (other than antigen recognition), what enhances B cell activation?
- simultaneous engagement of antigen receptor and CR2 OR TLR
What is the difference between T dependent and independent response?
T dependent response:
- to protein antigen
- isotope switching
- high affinity Ig
T independent response:
- to nonprotein antigen
- IgM
- low affinity Ig
What are haptens?
small molecules that can’t elicit immune response by themselves but do so by binding to larger proteins (poison ivy)
what is the 1st interaction of B and T cells?
simultaneous activation of T and B cells b y antigen and migrate toward each other. B cells will migrate back to follicles
What is the crosstalk between B and T cells?
- recognize peptide presented by B cells induce CD40L up regulation in T cells and produce cytokines
- engagement of CD40 and cytokine receptor on B cells lead to their proliferation and differentiation in plasma cells
remember, CD40 on B cells; CD40L on T cells
How does Ig isotope switching work?
change in the constant region of heavy chain
- variable region doesn’t change (recognition of antigen doesn’t change)
What does isotope switching require?
- specific cytokine produced by Tfh
- CD40L signal from Tfh cells
What happens with switch recombination ?
recombination brings VDJ exon next to a different C gene
Where does point mutation occur?
occurs in Variable regions
- selection of B cells with high affinity antigen receptors
