B cell Differentiation and Function Flashcards
in mature mammals, where do all blood cells that originate reside in?
bone marrow
what is the primary lymphoid organ for B cell differentiation in birds?
bursa of fabricius
how does the hematopoietic compartment mobilize in utero?
from the primordial yolk sac to the fetal liver and then the bone marrow prior to birth
what tool is used to identify B cell differentiation?
flow cytometry
We use commercial antibodies-tagged to a
______________ to identify changes in the cell surface proteins specific to the different stages of B cell differentiation.
fluorochrome
In the bone marrow, the pluripotent stem differentiates into a ___________ stem cell likely guided by stromal cells in the bone marrow
progenitor
what is the first discernable B lineage cell?
pro-B cell
what mediates the progenitor stem cell differentiating to the first discernable B lineage cell?
V(D)J recombinase
what are the two cell surface proteins?
CD10 and CD19
what does the pro B cell differentiate into?
pre-B cell
what synthesis is the pre-B cell characterized by?
μ heavy chain
what are the surrogate light chains of the pre-B cell?
Vpre-B (CD179a) and λ5 (CD179b)
what is the transmembrane domain that is a dimer cell surface protein adjacent the μ heavy chain?
Igα (CD79a) and Igβ (CD79b)
what does Igα (CD79a) and Igβ (CD79b) function as?
signal transduction molecules
what is the amino acid sequences in the transmembrane domain of the Igα Igβ cell surface protein and plays a role in B cell activation?
immunoreceptor tyrosine-based activation motifs (ITAMs)
what is the role that immunoreceptor tyrosine-based activation motifs (ITAMs) possess?
it is simply a differentiation stage that signals for the initiation of the true light chains.
what is the enzyme required for differentiation of the pre-B cell to an immature B cell?
Bruton’s tyrosine kinase (Btk)
Brutons’s Agammaglobulinemia Disease is an X-linked immunodeficiency where the B cell lineage could not advance beyond which B cell stage?
the pre-B cell stage
describe the process of a pre-B cell becoming an immature B cell?
- the light chains are assembled as a pair to the 2 heavy chains to form a complete IgM molecule
- Cell surface protein CD10 is downregulated,
CD19 is still expressed and CD20 is upregulated in expression
which B cell stage is when a functional IgM that it is tested for its ability to recognize non-self
and self-antigen?
immature B cell stage
what happens when the immature B cell BCR has a paratope that recognizes non-self?
it is released into the periphery to the secondary lymphoid tissues to finish its differentiation
what happens if the immature B cell strongly reacts to self-antigen (autoreactive)?
the immature B cell receives death signals and it dies via apoptosis within the bone marrow (negative selection)
what is central tolerance?
takes place in primary lymphoid tissue
designed to detect and eliminate autoreactive B cells before they can migrate into the
periphery
what is receptor editing?
Unique to immature B cells, select autoreactive immature B cells can escape apoptosis by
having their light chains undergo a further rearrangement of other V and J light chain segments
true or false: B cell central tolerance although well-regulated in the bone marrow, is not as tightly regulated as T cell central tolerance
true
Once an immature B cell survives negative selection and migrates out of the bone marrow into the bloodstream it reaches the ______
spleen
Upon entry into the white pulp of the spleen, it starts to upregulate the expression of ___.
IgD
when the B cell reaches the spleen, what stage is this classified as?
transitional B cell
what cell surface receptor for the cytokine is upregulated during the transitional B cell stage?
BAFF (B-cell Activating Factor)
what is the purpose of BAFF?
survival signal for transitional B cells produced by a number of different cells (i.e macrophages/monocytes, dendritic cells, neutrophils, epithelial cells and activated T cells)
what autoimmune disorders are linked to elevated levels of BAFF?
RA and SLE
how is an IgD fully expressed on the surface of the B cell at a higher percentage classified as?
naïve mature B cell
true or false: the antigen epitope specificity of the surface IgM and IgD are the same for each naïve mature B cell, although the role of IgD is still unclear
true
where do naïve mature B cells migrate to from the spleen and what are they classified as from there?
follicles, follicular B cells
what are marginal zone B cells?
Some naïve mature B cells that never reach the spleen, but instead migrate into the marginal zone of the spleen
what is the product of clonal B cell expansion besides activated B cells?
plasma cells and memory cells
when do B cells undergo clonal activation?
Once a B cell recognizes its cognate antigen epitope
what are plasma cells?
the effector B cell in that they are activated to produce large quantities of secretory antibodies.
what are two characteristics of plasma cells?
- life span: long vs short-lived
- plays a role in immune-mediated disease: long-lived plasma cells tend to reside in the bone marrow and short-lived plasma cells are associated with the mucosal tissues
true or false: plasma cells determine the level of protective immunity from a vaccine or a natural infection.
true
