B Cell Development and Immunity Flashcards
Where is hematopoiesis in the fetus?
developing liver
Where the primary site of hematopoiesis in adults?
bone marrow
How long can naive B cells circulate before apoptosis if they don’t encounter Ag?
2-3 days
What gene is expressed during heavy and light chain rearrangement?
RAG
When is TdT expressed?
From heavy chain rearrangment to light chain arrangment, but begins going away as light chain since no N regions are added
When are surrogate light chain genes expressed?
Only in heavy chain rearrangment region
What is receptor editing?
Immature B cells in the BM that are self-reactive will edit the light chain to try to eliminate self-reactivity, if it fails, self-reactive B cell retained in BM
What happens to a B cell that see Ag in an early stage without T cell help?
anergy
Can B cells recognize Ag presented on dendritic cells?
No, they must see ag in native conformation
What is an immune synapse?
Ag-activated B cells act as APC to T cells, induces immunological memory
What type of antigen is LPS?
T-independent 1 (TI-1)
What type of antigen is bacterial DNA?
TI-1 antigen that can activate B cells specific for bacterial surface Ag
How are T-independent responses different from T-dependent responses?
no memory, no IgG response, mainly IgM, short-lived
What are TI-1 antigens? What signal replaces T cell signal? What is activated?
LPS, bacterial DNA
- TLR-4 replaces T cell signals
- activates nonspecific B cells to produce IgM against bacterial surface
What are TI-2 antigens?
repeating polysaccharides with same epitope that causes crosslinking of receptors to activate
In what organ is the highest concentration of B cell development? what regions?
lymph nodes, in the medullary cords and germinal center
What is different about follicular dendritic cells? Where are they found? What is their purpose?
don’t process Ag, found in germinal centers, present Ag to B cells
Where is a focal point for B cells to undergo cell division, class switching and affinity maturation?
germinal centers
What causes hyperIgM syndrome?
lack of CD40 because of lack of T cells, no class switching, no germinal centers
What is a centrocyte?
dividing B cell in germinal center
What will IL-10 induce a B cell to differentiate into?
plasma cell
What will IL-4 cause a B cell to differentiate into?
memory B cell
