Exam 2- Chapter 6 Flashcards
B cells are kept in (SMALL/LARGE) amounts
Small
Source of B cells
Bone marrow stem cells
Phase 1 of B Cell development
B cell precursors acquire antigen receptors and go through rearrangement
Phase 2 of B cell development
Negative selection
Phase 3 of B cell development
Positive selection
Phase 4 of B cell development
B cells patrol for pathogens
Phase 5 for B cell development
B cell activation (results in proliferation and colonial expansion)
Phase 6 of B cell development
B cell differentiation (results in production of effector cells and memory cells)
Pluripotent hematopoietic stem cells give rise to:
B / T cells
B cell precursors
Pro-B cells
What type of gene rearrangement takes place with Pro-B cells?
Heavy chain gene rearrangement
What type of B cells undergo light chain gene rearrangements?
Pre-B cells
What happens when gene rearrangements are completed?
Pre-B cell becomes an immature B cell
Receptor types on a pluripotent hematopoietic stem cell
CD34
Receptor types on a common lymphoid progenitor
CD34 and CD10
Receptor types on a B cell precursor
CD34
CD10
And CD127
Receptor types on a pro-B cell
CD34
CD10
CD127
And CD19
Cells that assist with B cell maturation- act as the parents
Stromal cells
How long to stromal cells help B cells mature?
Until they are mature enough to leave the bone marrow.
How do stromal cells interact with B cells?
Through adhesion molecules
What growth factor does the stromal cell produce to help B cell mature?
IL-7
Where do B cells travel to after they leave the bone marrow?
Secondary lymphoid organs (lymph nodes, spleen, peyer’s patches)
Pro-B cells have to rearrange themselves into:
Productive rearrangement (antibody)
If the pro-B cell has an incorrect arrangement, it is called:
What happens if it cannot get to productive?
Non-productive arrangement
Will undergo apoptosis and die
Percentage of cells that survive heavy chain rearrangement
50%
B cells have ___#___ functional immunoglobulin
1
What happens after the first functional immunoglobulin is completed?
Rearrangement and transcription is halted to prevent formation of additional immunoglobulins
Choosing one allele over another:
Allelic exclusion
Allelic exclusion gives homogenous B-Cell receptors only with”
High avidity binding (single specificity)
Percent of B cells that have a successful light chain rearrangement
85%
Completed B cell receptors trigger a signal to shut down what?
The other light chain rearrangement
First bone marrow checkpoint checks for:
Formation of a functional heavy chain
Second checkpoint in the bone marrow checks for:
Formation of a. Functional light chain
What happens to B cells once they pass both check points?
They become immature B cells
What cells act as the checkpoints?
Stromal cells
What B cells bind to self-antigens
Self reactive or auto reactive
Healthy B cells mature and have what presented on the surface?
IgM and IgD
To eliminate self reactive B cells, what must happen?
They are presented to self-antigens on stromal cells in the bone marrow.
Only those negative for self may eventually leave the bone marrow
Percentage of immature B cells that have affinity for self antigens
75%
Out of 100 p/or B cells, how many make it out alive?
10
What happens if immature B cells self react?
They are directed to rearrange the light chain to change the specificity of the B cell receptor
Type of editing done to change the specificity of the B cell
Receptor editing
What happens if receptor editing is not successful in making a B cell non-self-reactive?
Colonial deletion- cell dies if it is not changed enough
How many chances does a B cell get to rearrange?
4 full chances- can be used at any time (So, if it rearranges 3 times during heavy editing, it only has one more chance before it has to die).
What happens if an immature B cell binds to a soluble self antigen after they leave the bone marrow?
They become anergic (lethargic)- they are unreceptive to anything out there
Type of tolerance in primary lymphoid organs, where self reactive cells die- controlled by stromal cells
Central tolerance
Type of tolerance in peripheral lymphoid organs, where the self reactive cells become anergic
Peripheral tolerance
When does maturation occur in immature B cells?
When they enter the secondary lymphoid tissues—- they are still immature while in the blood until they reach them.
They don’t know which lymphoid follicle they want, and will keep going from one to another until they find the right one. That is when they will become mature.
Between immature and mature B cells—- they are considered this as their circulate the system
Naive B cells
What displays antigens off of lymph nodes, looking to lure in B cells?
Stromal cells
Antigen matching results in:
Proliferation and differentiation into antibody-producing plasma cells
When B cells match an antigen, they are activated by:
The B cell will then secrete:
CD4 helper T cells
IgM antibody
Activated B cells migrate to:
A germinal center in a lymph node (centroblasts)
Why do lymph nodes swell?
Because a B cell found a match, so they are not making more B cells inside the lymph node.
What develop after the effector immune response subsides?
Memory cells develop
Memory B cells have a (LOW/HIGH) affinity, and are what type of antibodies?
High
Isotype switched antibodies
Memory B cells last how long?
They persist throughout a person’s lifetime. They are easily stimulated into plasma cells upon re-exposure to their antigen
