Ingham-3: B Cell Development I Flashcards
2 examples of primary lymphoid organs
bone marrow and thymus
Plasma cell
B cells that secrete Ab
Memory B cells
stay after infection just in case pathogen comes back again
stages of B cell development (x7)
HSC –> CLP –> pro-B –> pre-B –> immature B –> transitional B –> mature B
What stages of B cell development occur in bone marrow?
HSC –> Immature B cell
What stages of B cell development occur in secondary lymphoid organs?
transitional to mature B cell
What stage of B cells is committed into becoming a B cell?
pro-B cell
What earliest stage of B cell expresses IgM on cell surface?
immature B cell
What stage of B cell expresses highest amounts of IgD?
mature B cell
Function of Pax5
turns off expression of Notch
What is Notch?
T cell lineage transcription factor
When do Rag-1/2 genes turn on?
Pro-B cell stage
What is rearranged first in the heavy chain?
D and J
What is important in getting past the pro-B cell stage?
active Rag-1/2
What phenotype is expressed when an organism lacks Rag genes?
SCID (severe combined immunodeficiency disorder)
What do transgenic genes mean?
addition of DNA (synthetic)
What does knock out genes mean?
alter a gene so it cannot make functional protein or mRNA product
What do knock in genes mean?
replace a functional gene with a mutated version of it
What characterizes the development of a pre-B cell?
rearrangement of heavy chain
2 stages of pre-B cell
- early/large
- late/small
What is IgH?
heavy chain gene
What makes IgH helpful in promoting DNA transcription?
- has promoters upstream of V segment
Function of promoters in IgH?
recruits RNAPII to start transcription
Where are enhancers located in IgH locus?
between constant and variable regions
What is the B cell specific TF that binds IgH promoter?
Oct-2
Surrogate light chains are composed of?
- VpreB
- lambda5
Do all pre-B cells express surrogate light chains?
yes
What is VreB similar to?
VL
What is lambda5 similar to?
CL
What structure of the surrogate light chain allows pre-BCRs to self-aggregate?
VpreB has extra C-terminal acidic residues and lambda5 has basic N residues
What is the mutated gene in people who have X-linked agammaglobulinemia (XLA)?
btk gene
