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79 Cards in this Set
- Front
- Back
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Activated B cells can give rise to what two type of cells? |
plasma and memory B cells |
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Where does negative selection occur for B cells? |
bone marrow |
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What do be cells bind to on the virus? |
viral coat protein - epitope |
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What happens after the virus is bounded to the antibody ? |
the virus gets degraded then presented on the surface of the B cell via MHC |
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What cell activates B cell |
T helper cells |
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What type of linking is antigen and antibody ? |
cross-likning of membrane iG - Ig is bounded by two Ab |
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Activation of B cells causes 3 changes in phenotype function - what are they? |
1) clonal expansion 2) cytokine responsiveness 3) plasma cell formation |
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Plasma cell formation is due to? |
antibody secretion |
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increasing cytokine responsiveness is due to an increase in? |
increased expression of cytokine receptors |
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increasing in clonal expansion is caused by ? |
entry into cell cycle: mitosis |
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Through clonal expansion, what are the 4 types of differentiation |
1) antibody-secreting plasma cell 2) isotope switching 3) affinity maturation 4) memory B cell |
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What types of cells are not long-living after clonal expansion? |
plasma cells
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What cells are long-living after clonal expansion? |
memory B cells |
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Where does clonal expansion usually take place in? |
secondary lymphoid organs |
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Why is it important for B cells to increase their cytokine receptors ? |
it allows the B cells to be more sensitive to the immune response |
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In primary antibody response, what is the responding cell? |
naive mature B cells |
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In secondary antibody response, what is the responding cell? |
memory B cell - has membrane bound antibody on it |
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What is the main Ig in primary response? |
iGM |
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What is the main Ig in secondary response? |
IgG |
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What is the difference between primary and secondary response? |
1) lag period vs no lag period 2) low vs high conc of antibodies 3) low affinity vs high affinity (IgG isotypes) 4) more IgM vs more IgG |
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What type of clonal expansion is found in primary response that isn't found in secondary response ? |
class switching |
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what class switching usually occurs? |
IgG |
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Under what influence and what cell causes class switching |
under the influence of Thelper cells releasing cytokines |
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What type of B cells provide a rapid/strong response to secondary infection |
b cell memory |
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B cell proliferation causes |
clonal expansion |
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What do B cells differentiate into ( two types of cells)?
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memory and plasma-secreting antibody |
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What is the first signal for B cell activation ? |
Ag binding to Ab |
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What causes the intracellular signalling cascade? |
Igalpha and iG beta |
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Signal one increase what expression |
MHCII and B7 |
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What provides the necessary co-stimulatory signal to activate the Thelper cell? |
the binding of B7-CD28 |
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What causes the induction of CD40L ? |
When the T helper cell recognizes Ag ( when T cell binds other APC peptide on B cell) |
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Where is the CD40L located on- what cell? |
T cell |
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What is the signal 2 of b cell activation ? |
CD40- CD40L |
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Signalling from CD40 ligation induces (2 things) |
1) NK-kB transcription factor activation
2) expression of cytokine repartees on the B cell |
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What is the third signal for B cell activation ? |
( cytokine) made from T cells- binding receptors on the B cell |
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when cytokine binds to cytokine receptors on the B cell , what occurs? |
B cell proliferation and differentiation |
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What cell cycle does signal 1 and 2 occur in? |
Go-G1 |
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What cell cycle does signal 3 occur in? |
G1- mitosis |
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B cell differentiation causes 3 things |
1) class switching 2) affinity maturation 3) plasma or memory b cell formation |
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Signal 1 in T cells is Signal 1 in B cells |
antigen specific TCR engagement Ag binding Ab |
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Signal 2 in T cells Signal 2 in B cells |
CD28/B7 CD40/CD40L |
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Signal 3 for b and T cell |
cytokines directing T and B cell proliferation and differentiation |
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Where are the cytokine sources? |
1) Thelper cells
2) other activated APC ( macrophages and dendritic cells) |
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Where does T helper cell begin to synthesize cytokines ? |
when helper T cells adhere to the B cell |
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what type of cytokines does Th make? |
Il-4 |
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When T helper and B cell come into contact, what 2 things being to synthesize on the T helper cell? |
1) Il-4 2) CD40L |
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What is the interface between APC and T cell called? |
immunological synapses |
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What is the centre for producing microtubule skeleton proteins? |
MTOC |
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What does MTOC stand for? |
microtubule-organizing center |
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In the T cell, what cells are rearranged so that cytokine is released close to point of contact? |
MTOC, golgi and talin ( cytoskeletal protein) |
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The helper T cells reorients its what two things towards the B cell? |
cytoskeleton and secretory apparatus |
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The release of IL-4 is what type of releasing ? |
directional |
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After clonal expansion , what happens ? |
differentiation |
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What types of differentiations can happen? |
1) antibody secretion 2) isotype switching 3) affinity maturation 4) memory B cell |
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What induces activation of signalling cascade in the B cell |
cytokines |
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Where is the promoter region found in order to induce class switching? |
upstream of the switch site |
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What causes NF-kb to be induced ? |
the binding of CD40L to CD40 |
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What cell produced IFN-Y and what transcription factor does it bind to? |
Thelper cell and binds to STAT1 |
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What affect does STA1 have regards to isotope switching?
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IgG subclasses ( Ig1 and IgG3) |
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What causes isotype switching to IgE |
Il4-4 binding to STAT6 |
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What types to cytokines produced is responsible for class isotype switching to IgA
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cytokines produced in the mucosal tissues (TGF-beta0 |
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TI ( thymus independent) doesn't rely on what type of cells? |
CD4 T cells |
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What type of antigen do TI tend to recognize? |
non-protein antigen |
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TI antigens tend to be what type of nonprotein antigens? |
large polymers of sugars with repeating epitomes |
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TI type 1 binds to what receptors? |
mitogen and possibly BCR |
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TI type 1 induces mainly what Ig? does it ave memory? |
IgM and usually no memory |
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the binding of the non-protein antigen induces what |
proliferation |
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What type of activation does TI type 1 cause? |
polyclonal activation |
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What is polyclonal activation |
diverse B cell clones to secrete antibody that are NOT specific for TI-1 Ag |
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The signal in TI type 1 is similar to wha signal for TD
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CD40/CD40L |
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TI type 2 antigens is attached to what receptors? |
BCR - high avidity of cross linking BCR |
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What can type 2 do that type 1 cannot do in TI? |
class switching and some memory B cells |
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What types of antigens bind to type 2 TI? |
bacterial products : endotoxin, dextran, flagellin |
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What types of antigens bind to type 1 TI? |
LPS |
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for type 2 TI, the antigen is in what form- structurally ? |
polysaccharides of multiple IDENTICAL epitopes |
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TI-2 can do what alone ? |
signal the production of IgM antibody |
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What cytokines does activated dendritic cells release? |
BAFF |
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What can BAFF induce ? |
class switching |
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TI-2 class switching is important for what type of bacteria ? |
capsulated - H. influenza |
