Flashcards in B cell Immunity- L10 Deck (29):
B cells develop in the
Bone marrow, called mature naive B cells when they leave the marrow
B cells develop from what cell with what marker?
Pluripotent hematopoietic stem cells with marker CD34
Common lymphoid progenitors have what marker?
CD34 and CD10
B-cell precursors have what markers?
CD34, CD10, CD127
Pro-B cells have what markers?
CD34, CD10, CD127, CD19
What happens in the early pro B stage?
D-J rearrangement of heavy chain
What happens in the late pro B stage?
V-DJ rearrangement of heavy chain
What happens in large pre-B cells stage?
VDJ is rearranged and mu heavy chain of Ig is made
What happens in small pre-B cell stage?
VDJ is rearranged, V-J of light chain is rearranging, and mu chain is in the ER of Ig
What happens in an immature B cell?
VCJ is rearranged, VJ is rearranged, gamma or kappa of light chain IgG is made, IgM is on surface.
What percentage of cells produce a productive heavy chain and survive to become pre-B cells?
What region does the light chain not have?
What are the two checkpoints in becoming an immature B cell?
1. Pre-B cell receptor
2. B cell receptor
If these aren't met the cell will apoptose
-Chromosomal aberration during B cell development
-MYC and Ig on chromosomes 8 and 14 respectively get translocated
B-1 cell characterstics
-Produced in fetus
-Few N regions in VDJ junctions
-Smaller V region repertoire
-Primarily located in peritoneal and pleural cavities
-More IgM than IgG
-Little somatic mutation
-Little memory development
-If no reaction with a self antigen--moves to blood to express IgD and IgM
-If reaction with self the immature B cell is retained in bone marrow and RAG gene is reexpressed to try and rearrange again. Will continue rearranging until a nonself receptor is expressed.
Interaction of immature B cells with monomeric antigen induces a state inactivity called anergy. Signaled to make IgD and become unresponsive to antigen.
B cell trafficking in the periphery
-B cell area in the cortex
-Enter through HEV
Attracts immature B cells to HEV and into lymph node
Attracts B cells into lymph node
Attracts B cells into the primary follicle
Follicular dendritic cells
Drive the final maturation of B cells
B cells mature where?
Germinal centers of lymph nodes
How do B cells signal?
-Cross linking of B-cell receptors by antigen
-Clustering of antigen receptors allows receptor-associated kinases to phosphorylate ITAMs
-SyK binds to doubly phosphorylated ITAMs and is activated on binding
B cell coreceptor 1
-Consists of CD81, CD19, and CR2
-Binding of CR1 to C3b bound to a pathogen facilitates its cleavage by factor 1 to iC3b and C3d.
-CR2 component of the B-cell co-receptor can then bind to C3d
B cell coreceptor 2
-Cooperate in B-cell activation by a pathogen or a soluble agent
T-cell independent antigens
-B1 cells generally T independent
-Antigen binds B cell coreceptor which activates it
How do B and T cells find each other?
-B cells look for specific antigen displayed by FDC is B cell area
-T cells look for specific antigen presented by dendritic cells in T cell area
-When T cells proliferate, B cells move toward them