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Humoral Immune Responses
Monday April 5th @10AM
36
Medical
Professional
04/05/2010

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Cards

Term
what's an isotype?
Definition
heavy chain portion of antibodies differentiate them
Term
what's a plasma cell?
Definition
secretory phase of B cells
Term
4 antigenic structures recognized by antibodies:
Definition
peptides, polysaccharides, lipids and nucleic acids.
Term
what are the 6 activation stages of B cell maturation?
Definition
1) contact and recognition of bug. 2) activation signals through BCR and via T help. 3) clonal expansion and differentiation. 4) antibody secretion. 5) isotype switching. 6) affinity maturation
Term
what are the two possible isotypes of a naive B cell?
Definition
IgM+ and IgD+
Term
what are 3 anatomical sites where B cells respond to bugs?
Definition
secondary lymphoid organs, mucosal surfaces, peritoneal cavity.
Term
where do you find marginal zone B cells?
Definition
spleen white pulp marginal zones
Term
where do you find B2 or conventional B cell?
Definition
lymph node germinal centers
Term
where do you find B-1 B cells?
Definition
mucosal tissues or peritoneal cavity
Term
what is the primary response of B cells? secondary response?
Definition
first exposure to bug. next time around, also called recall response.
Term
1) which isotype is usually present in primary responses? 2) what antibodies are present in secondary responses?
Definition
1) Usually IgM>IgG. 2) Relative increase in IgG (but can change to IgA or IgE)
Term
what are NFkB, NFAT, AP1, myc ?
Definition
transcription factors that play a role in cytokine production and proliferation.
Term
what is a BCR?
Definition
antibody molecule (B cell receptor)
Term
what is the purpose of the complement molecule?
Definition
improve signaling and lead to B cell activation
Term
what are two types of complement molecules?
Definition
CR2 and C3d
Term
what is the significance of the secretion of low levels of IgM?
Definition
early phase of humoral immune response
Term
what is the T cell zone of the lymph node called?
Definition
parafollicular cortex
Term
what is the B cell zone of the lymph node called?
Definition
lymphoid follicle
Term
can T cells recognize the microbe directly?
Definition
NO! it recognizes linear epitopes, or itzy bitzy pieces of the microbe, NOT the whole thing.
Term
what does CD stand for?
Definition
Cluster Differentiation
Term
what does CDR stand for?
Definition
complementarity determining region
Term
can the B cell present antigen to T cells?
Definition
yes, it engulfs a bug then presents a MHC class II that grabs a CD4+ T helper cell.
Term
what is the function of the CD40/CD40L engagement between an antigen presenting B cell and a T helper cell?
Definition
allows T cell to secrete cytokines and activates the B cell to proliferate and differentiate.
Term
why so much control in B cell activation?
Definition
to keep the immune system from being hyperactive, on a hair trigger with every antigen it finds. It works best with the "belt and suspenders" approach.
Term
what is the main function of IgM?
Definition
complement fixation
Term
what is the main function of IgG?
Definition
opsonization, viral neutralization
Term
what is the main function of IgE?
Definition
mast cell degranulation, helminthes
Term
what is the main function of IgA?
Definition
mucosal immunity (transport through epithelial cells.
Term
is isotype switching reversible?
Definition
no. it is irreversible.
Term
how does isotype switching work?
Definition
in response to T cell signals, recombination of genes takes place and produces different isotypes. Relies on rearranged gene segments
Term
what happens when there is no signal from T cells during isotype switching?
Definition
stay as IgM
Term
what is affinity maturation?
Definition
way of improving strength of binding between antibody and antigen.
Term
what allows for a change in affinity in antibody binding strength?
Definition
a hypermutation in the CDRs (complementarity determining regions).
Term
where does affinity maturation occur?
Definition
germinal centers of lymph nodes
Term
what is the difference between T-independent and T-dependent antigens?
Definition
T-dependent antigens are usually small monomeric (known as haptens). Whereas T-independent antigens are polymeric (LPS, glycolipds, nucleic acids).
Term
how does negative feedback work in the regulation of humoral immune responses?
Definition
B cells can receive direct signals from receptors that engage antigen and from cytokines from T-cells and other cells.
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