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57 terms

Chapter 4 Micro

STUDY
PLAY
RAG:
• Binds between D & J to 12 and 23 and splices
TdT (terminal deoxynucleotical transferase):
• Adds N nucleotides
Surrogate light chain:
• Bind to heavy chain to check for correctness of chain before cloning
VLA-4:
• Integrin on B cell
• Binds VCAM on bone marrow stromal cell
VCAM:
• Integrin on bone marrow stromal cell
• Binds VLA4
KIT:
• Binds to SCF on stromal cell
SCF:
• Binds to KIT
• Stimulates IL-7 release
IL-7:
• Stimulates growth and proliferation when surrogate chain is bound
CCL19 &CCL21:
• Chemokine released by stromal cells to attract B cells to HEV
CCL13:
• Chemokine released by FDC to attract B cells to primary follicle
TNF-α
• Is secreted in follicles
• BAFF (B-cell activating factor in TNF)
• LT (lymphotoxin)
BAFF (B-cell activating factor in TNF):
• Produced by FDCs
• Binds to B cell receptor and promotes survival and maturation in follicle
LT (lymphotoxin):
• Produced by B cells
• Binds to FDC to preserve integrity of FDC network
2 processes happening in germinal centers:
• Isotype switching
• Hypermutation
Isotype switching:
• Changing of the constant region
AID:
• Deaminates Cytosine to Uracil at the switch sequence
UNG (Uracil-DNA-glycosylase):
• Uracil is removed leaving a nucleotide that lacks a base
APE1:
• Excises the abasic nucleotide and leaves a nick in DNA
Hypermutation:
• Undergone by B cells in germinal center after the recognition of an antigen
• Attempt to better match antigen
AID (Activation-induced cytidine deaminase):
• Deaminates Cytosine to Uracil
Immunoglobulin (Ig)
• All proteins which structurally resemble Abs.
Antibodies (Abs)
• Proteins made by lymphocytes and plasma cells, which specifically react with molecules termed antigens (Ags).
Papain:
• Cleaves before (above) disulfide bond
• Leaves 3 fragments
Pepsin:
• Cleaves after (below) disulfide bond
• Leaves 3 fragments
B cell ITAMs:
• Blk
• Fyn
• Lyn
• Syk
• Activate CD19 co-receptor
CD19
• B cell surface protein
• Activated by B cell ITAMs after crosslinking
• Responsible for intracellular cascades to produce transcription factors
IP3:
• Activates the transcription factor NFAT
DAG
• Activates the transcription factor NFkB
GEFs:
• Activate AP-1 transcription factor.
NF-kB, NFAT, and AP-1:
• Transcription factors that induced by crosslinking antibodies
• Encourage B cell proliferation and differentiation to plasma cells
CR2 AKA CD21:
• Binds C3d or iC3b for opsonization
• Stimulates B cell through CD 19 (make transcription factors)
CD40:
• B cell protein
• Expressed naturally on B cell surface
CD40L:
• T cell protein
• Expressed after T cell recognizes MHC:peptide complex (foreign) that B cell presents from ingestion of a pathogen
• Binding with CD40 causes T cell to release cytokines
Medullary cords:
• B cells migrate here to produce IgM and exit to site of infection
Primary follicle (germinal center):
• B cells migrate here to undergo hypermutation and antibody switching
CR1 on stromal cells:
• Breaks down C3b to iC3b or C3d
CR2 on stromal cells:
• Binds iC3b or C3d and drags pathogen for presentation
B cell low affinity interaction with stromal cell:
• Apoptosis
B cell high affinity interaction with stromal cell:
• Stromal cell interaction (BAFF & LT)
• T cell interaction (CD40L and cytokines)
IL10:
• Produced by TH cells
• Induces B cell to differentiate into plasma cell which migrate to bone marrow
IL4:
• Produced by TH cells
• Induces B cell to differentiate into memory cells (IgG & IgE)
IL5:
• Produced by TH cells
• Induces B cells to differentiate into IgA
TGF-β:
• Th2
• Induces IgG2b and IgA
IFN-γ:
• Th1
• Induces IgG3 and IgG2a (Fc)
LPS presentation to T cell:
• Is not done
• Instead TLR is used to signal B cell to make IgM
TI-2 activation:
• Activates B cells by having a high number of crosslinks with antigen
FcRn:
• Recognizes IgG and pulls it across the placenta
pIgR:
• Receptor on BM side of cell
• Binds to J chain and pulls it into lumen (intestine)
Monomeric IgA location in body:
• Bloodstream
• Extracellular fluid
IgG location in body:
• Bloodstream
• Extracellular fluid
• Transferred to fetus (FcRn)
IGM location in body:
• Bloodstream
Dimeric IgA location in body:
• Mucosal surfaces
• Breast milk
IgE location in body:
• Beneath epithelial surfaces (skin, resp tract, GI tract)
FcγRI:
• High affinity Fc receptor that recognizes IgG1 and IgG3
FcγRIII:
• NK cell receptor that recognizes Fc portion of antibody
• NK cells release cytotoxic granules
FcγRIIB1:
• Inhibitory receptor on B cell that shuts down Rh response when too much IgG is present
FcεRI:
• IgE receptor on mast cells