Quiz 5 Part 1 Flashcards
B cells derive from what precursor
common lymphoid
The bone marrow generates around ______B cells per day
60 billion
The bone marrow generates around 60 billion B cells per day.
This this mean there are 60 billion B cells circulating in your blood/lymph
NO - these are kept as a reserve in case you get infected
B cells have how many distinct phases of development?
6
Do all B cells progress through all 6 stages of development?
NO. there are checkpoints where some B cells get “kicked out” before they go through all 6 stages
true or false:
only a fraction of B cells ever encounter an antigen
true
in B cell development:
phases 1-3 occur in __________
phases 4-6 occur in __________
phases 1-3 occur in PRIMARY lymphoid tissue (bone marrow and the thymus)
phases 4-6 occur in SECONDARY lymphoid tissue
state phases 1-3 of B cell development (occurs in primary lymphoid tissue)
- Assembly of a B cell receptor
- ELIMINATE B cells that bind “self” antigen
- B cell passes the test and is allowed to leave the bone marrow
“generation of diverse and clonally expressed B-cell receptors in the bone marrow.”
what phase of B cell development is this?
what is a “nickname” for this phase?
phase 1
“repertoire assembly”
“alteration, elimination, or inactivation of B cell receptors that bind to components of the human body”
what phase of B cell development is this?
what is a “nickname” for it?
phase 2
this is known as NEGATIVE SELECTION
“Promotion of a fraction of immature B cells to become mature B cells in the secondary lymphoid tissue”
What phase of B cell development is this?
what is a “nickname” for it?
3rd phase
POSITIVE SELECTION
If these B cell receptors DO recognize “self” and don’t get eliminated, what occurs?
an autoimmune disease
List phases 4-6 of B cell development (occurs in secondary lymphoid tissue)
- Factors in secondary lymphoid tissue attract circulating B cells
- B cell is activated by antigen in secondary lymphoid tissue
- Factors differentiate B cells into plasma cells
“recirculation of mature B cells between lymph, blood, and secondary lymphoid tissues”
what phase of B cell development is this?
what is an easier way to put it?
phase 4
searching for infection
“activation and clonal expansion of B cells by pathogen derived antigens in secondary lymphoid tissue”
what phase of B cell development is this?
what is an easier way to put it?
phase 5
finding infection
“differentiation to antibody-secreting plasma cells and memory B cells in secondary lymphoid tissue”
what phase of B cell development is this?
what does this mean in a nutshell
stage 6 (last stage)
attacking the infection
is the assembly of the B cell receptor dependent on genetics?
yes
Progression through phases of B cell development is accompanied by the expression of _________
surface makers
ALL hematopoietic stem cells express what surface marker?
CD34
The expression of CD34 along with CD10 indicates what?
a common lymphoid progenitor
expressing CD34 +CD10 + CD127 indicates what?
B cell precurso
expressing CD34 + CD10 +CD127 +CD19 indicates what?
this is a pro B cell
list the names of the 7 actual cells involved in B cell development (in order)
stem cell
early pro-B cell
late pro-B cell
large pre-B cell
small pre-B cell
Immature B cell
MATURE B CELL
in which phases is somatic recombination happening?
explain
in early pro-B, D-J rearrangement is happening in the heavy chain
in late pro-B, V-DJ rearrangement is happening in the heavy chain
in small pre-B, V-J rearrangement is happening in the light chain
when is RAG turned OFF
after V-DJ somatic recombination (late pro-B phase)
what happens after RAG is turned off?
there is a heavy chain checkpoint during the large-pre-b phase
besides the heavy chain checkpoint and RAG being turned off, what else is happening in the Large pre-B stage?
the mu heavy chain is made
when does the light chain start being made?
RAG is back on
small pre-B stage
the B cell receptor is assembled during which phase?
immature B cell
at the heavy chain checkpoint, what exactly are you checking for?
what phase is this happening in?
making sure that the heavy chain you just made is capable of binding light chain
happening in large pre-B phase
does an immature B cell exit the bone marrow? explain
YES
immature B cell exits the bone marrow with its B cell receptor, looking for an antigen.
Are stromal cells lymphoid or non-lymphoid
non lymphoid
where are stromal cells located?
in the bone marrow
what is the general function of stromal cells?
to provide signals that are critical for B cell development
name the TWO DISTINCT FUNCTIONS of stromal cells
-provide specific contacts that regulate development
-produce growth factors that act on B cells at different stages of development
WHERE do most immature B cells make first contact with stromal cells?
in the subendosteum —a region proximal to the inner surface of bone
most immature B cells make first contact with stromal cells in the SUBENDOSTEM (a region close to the inner surface of bone)
where do more mature B cells move?
medially toward the central cavity
as development proceeds, do B cells require more or less contact with stromal cells?
B cells require less contact with stromal cells as they develop.
eventually, contact is lost and B cells can exit the bone marrow
what do stromal cells use to create a strong contact between stromal cells and B cell precursors?
cell adhesion molecules (CAMs)
what stem cell factor (growth factor) exists on the stromal cell?
SCF
what is the name of the stem cell factor receptor on the B cell?
Kit
in which phase of B cell development does SCF bind to Kit?
early pro B
In which phase of B cell development does the stromal cell secrete a cytokine?
what is the same of the cytokine?
what is the name for the receptor of this cytokine on the B cell surface?
late pro-B
IL-7
IL-7R
Growth factors promote _______
differentiation
