B cell activation and antibody production part 2 Flashcards
Progeny of the clone may differentiate into plasma cells that produce___ or isotype switch
IgM…
activation of B cells is initiated by?
specific antigens by surface BCR’s
B cell differentiation results in an increasing fraction of the ___ protein produced as the secreted form
U (meu)
in T dependent response, some the progeny activated IgM and IgD expressing B cells undergo ? and produce abs with heavy chains of different classes. delta, alpha, and epsilon
Heavy Chain Isotype switching
Where does Isotype switching occur?
germinal centers driven by Follicular T helper cells
class switching occurs in response to?
changing the constant regions of heavy chains
Activated B cells can secrete IFN-gamma and isotype switch to a plasma cell that secretes?
IgG to activate complement system.
helminth infections likely influence Follicular T helper cell differentiation to these cells, which produce Th-2 type cytokines during the germinal center reaction.
IL-4+ Follicular T helper cells
B cells in mucosal tissue switch to?
IgA secreting plasma cells
Switching to IgA involves?
TGF-beta
in Immunodeficiencies related to the CD40-CD40L axis the antibody response to protein antigens is dominated by
IgM antibodies
The mature B cells first produce IgM Ig’s. the rearranged VDJ sequences are positioned directly adjacent to other C genes. Every C gene is preceded by ___that controls the rearrangement process
Switching the S sequence
what is the key enzyme required for isotype switching and affinity maturation?
Activation Induced Cytosine Deaminase (AID)
AID expression is activated by?
CD40 signals from follicular T cells
AID deaminates cytosines in ss-DNA converting Cytosine residues to?
Uracil residues
During the actual binding of B cells to the T helper cell surface, which is not involved?
Ig
if you could analyze at the molecular level a plasma cell making IgA ab, you wouldnt find?
mRNA specific for U (meu) heavy chains
Affinity maturation is observed ONLY in antibody response to?
T-dependent protein antigens
somatic hypermutation of Ig V genes and selection of B cells with high affinity Ag recep
…..
what happens in the dark zone of germinal centers?
proliferation and point mutation in V-region of H/L chains
Mutated Ig with higher affinity binds antigen presenting FDC and survives in the?
light zone of germinal centers
mutations in which genes, increase with time after immunization and with repeated injections?
V genes
Multiple myeloma is a cancer which has arisen from a
plasma cell
many non protein antigens, such has polysaccharides and lipids, stimulate ab production in the absence of Th cells
…..
T-independent responses involve which type of antigens?
non-protein: polysaccharides and lipids
T-dependent responses involve which type of antigens?
protein
these cells respond readily to the T-independent antigens mainly in the peritoneum and in mucosal sites
B-1 cells
CD4+ helper T cells cannot recognize which type of Antigens?
T-independent antigens: polysaccharides, glycolipids, and nucleic acids
what is the function of the complementarily determining region of an Ig?
determine antibody specificity and are found on both the heavy and the light chains
if you wanted to check for the presence of memory B cells from your vaccine subjects by taking some of their B cells and re-stimulating them in vitro with antigen, the best place to get some memory cells would be from?
Blood
