B cell immunity - part 2 Flashcards
What B cells initiate the secondary immune response?
Memory B cells
Do we still need a Tfh cell for the secondary response?
Yes
Memory responses are more protective as _____ B cells respond to protein antigen, leading to _____ Abs produced.
more
more
The memory responses produce more of what?
More long-lived plasma cells and more memory B cels
What are differences between the primary B cell response, and subsequent ones?
Primary response takes longer to initiate.
Primary response secretes IgM first, then other antibody types later; secondary response has an increased number of IgG, IgA and IgE earlier.
Secondary response is stronger than the primary response
What are non-protein antigens that B cells can bind to?
Lipids and polysaccharides
When B cells bind to non-protein antigens, what cell types are produced by clonal expansion?
short-lived plasma cells only
What is a major difference between B cells responding to protein antigens, and responding to non-protein antigens?
No Tfh cell input is needed when responding to non-protein antigens
Why are Tfh cells not needed when a B cell responds to a non-protein antigen?
Non-protein antigens have very high affinity for BCR
What are the only antibodies produced when responding to non-protein antigens?
IgM
What is a major downfall of the response to non-protein antigens?
No long term memory
IgD:
- levels in the blood?
Function?
Where are most of them found?
Low levels in blood
Ab function is unknown/ bind pathogens as BCR
Most remain bound to naive B cells
IgM:
- location?
- Key characteristic?
Main form?
Mainly found in blood
First antibody produced in primary immune response
Pentameric
Which antibody type is the first one produced in newborns?
IgM
IgA:
- most abundant where?
- what does it provide to a newborn? How is this accomplished?
Most abundant Ab in secretions (mucus, tears, saliva, breast milk)
Provides passive immunity to newborn; maternal IgA transferred to newborn via breast milk
IgA is mainly produced where?
MALT tissue
These antibodies can cross the epithelial barrier and can protect us from invading pathogens or toxins that may be sitting in our mucosal membranes.
IgA
IgE:
- instrumental in immunity against what type of pathogen?
- involved in which type of reaction?
Instrumental in anti-parasitic immunity
Involved in allergic reactions
Increased serum IgE is generally indicative of what?
Either parasitic infection, or allergic reactions
IgG
- most abundant where?
- provides what to newborns? How?
Most abundant antibody in blood and tissues
Provides passive immunity to newborn - maternal IgG is the ONLY isotope that can cross the placenta
How do IgG antibodies enter infected tissues?
Via inflammation
What are the mechanisms of antibody-mediated destruction of extacellular pathogens?
Which antibodies are involved?
Neutralization and Triggering phagocytosis
IgM, IgG, IgA
What are the antibody titers in the serum (i.e. which is most abundant in the blood, to which is the least?
IgG, IgA, IgM, IgD, IgE
What is neutralization?
Antibodies block a virus from binding to its target cell by binding to the virus’ surface and preventing it from entering the host cell
