3 Humoral Immunity I Flashcards
T-F—each mature B cell clone in the periphery expresses only one type of antibody?
True
T-F—in a typical infection there are many B cells that can bind to a single antigen in the periphery?
False—few
What is the difference between a B-1a cell and B-1b cell markers?
B1-b does not have CD5
What is the difference between marginal zone B-2 cells and Follicular B-2 cells markers?
Marginal zone does not have CD23
Are many B-1 cells produced in the adult?
No–few…most are generated in fetus and neonate liver and bone marrow
Can B-1 cells self renew in the periphery?
yes
Are many B-2 cells produced in the fetus?
No- some, FO B cells in the neonate but are produced continuously throughout life in bone marrow
Are marginal zone B cells present at birth in the periphery?
No
T-F–rearrancged heavy chains contain only a subset of Vh elements present in germ line? What does it mean?
True- antibodies produced by B-1 B cells tend to bind certain types of macromolecules
Where do B-1 cells primarily localize?
to serous body cavities–lung pleura and peritoneal cavity
Are B-1 cells present in large numbers in the spleen and lymph nodes?
No
What cells are a main source of Natural IgM?
B-1 cells spontaneously produce without infection
What are the 2 distinct B 2 subsets?
marginal zone and follicular
What is the antibody repertoire biased towards recognizing in MZ cells? Where does MZ localize?
- microbial products
- white puple marginal zone of spleen.
Where does FO B cells localize?
follicles in spleen and lymph node—it is the most abundant B cell subset
Activated follicular B cells migrate where?
toward T cell zones to interact with helper T cells
What are marginal zones exposed to?
Red pulp–exposed to antigens in blood stream and will secrete IgM into blood stream
Does BCR have an intrinsic signaling ability?
No
What connects antibody to intracellular signaling pathways?
CD79alpha
Cd79beta
What coreceptor molecles amplify signals of Ig alpha/beta?
CD19, CD,1, CD81
What is signal 1 of the B cell activation?
engagement of multiple BCRs
What is signal 2 of the B cell activation?
Provided by an innate receptors or CD4 T cells
What is signal 3 of the B cell activation?
cytokines produced by neighboring interacting cells
Signal 1 alone causes?
cell deletion or anergy
What does the need of 3 signals create?
dependence on activation of other cell types to safeguard against spurious antibody responses
What does TD stand for in a TD response?
thymus dependent–thus require CD4 help
Are TD responses operating in later or earlier stages of immune response?
Later
Does TD response generate high affinity antibodies?
yes
Does TD establish long term immunity as elicited by infection or vaccination?
Yes
Are there more or less magnitude of TI responses than TD responses?
Less—and contribute little to long term humoral immunity
What are TI responses induced by?
polymeric complexes containing repetitive structures
What type of antibodies typically come from TI response?
IgM
What is the key benefit of TI response?
source of antibodies in early stages of immune response
When are TI responses not effective? Why
in the neonate–marginal B cell compartment is poorly developed
What type of TI antigen–polymers displaying repeating copies of epitopes that can engage multiple B cell receptors on a single cell?
Type 1 antigen [signal 1]
What type of TI antigen–contain a component that can directly activate patter recognition receptors?
Type 1 TI antigen [signal 2]
What type of TI antigen- polymers displaying repeating copies of epitopes that can engage multiple B cell receptors on a single cell?
Type 2 TI antigen [signal 1]
What type of TI antigen- does not inherently contain a means to provide a second signal?
Type 2 TI antigen
What type of TI antigen- able to recruit innate components (complement)/
Type 2 TI antigen [signal 2]
Is lipopolysaccharide a type1 or type 2 antigen? can they be whole cells, aggregates and debris?
type 1 TI antigen, yes
[forms BCR complex and can engage TLR4, and elicits cytokine production from innate cells…all 3 signals]
What displays LPS on surface?
Gram negative
Are polysaccharides an example of a type II TI antigen?
Yes- provides signal 1 but not signal 2
TI responses are mounted primarily by >? why?
B-1 and Marginal Zone B cells
[Why? repertoire is enriched for reactivity against microbial antigens, their anatomic location facilitates, biochemically wired for rapid response]
