PSIO202 Exam 2 Lecture 19 Flashcards
How does a b cell acquire its receptor/antibody?
random genetic mutation
What happens when an antigen binds to the antigen receptor on a b cell?
the b cell is activated and produces plasma cells
What do plasma cells do?
produce free antibodies with the same receptor as the one’s which were on the surface of the b cell
At what location do antibodies fight pathogens?
in the ISF and extracellular fluid
Do B cells leave the lymphatic system?
No, just the antibodies
What are the 4 steps of antibody mediated immunity?
recognition, activation, proliferation/differentiation, and killing
Explain the b cell process of recognition and activation?
b cells encounter antigens which bind and cause the b cell to become activated, the antigen is endocytosed and inserted into the membrane on an MHC2 protein. Helper T cells bind to the MHC2 and begin secreting cytokines that promote proliferation and differentiation of both the B cells and T cytotoxic cells.
Unlike T cells which can only see microbes when their peptides are presented on an MHC, B cells can see…
epitopes on many kinds of large molecules
How many antibodies per hour can be secreted by a plasma cell?
100 million per hour
How long can memory B cells remain in the body?
20+ years
What are the co-stimulators when a helper T cell binds to the MHC2 on a b cell?
CD4 and IL B7
What does IL B7 do during B cell activation?
it stimulates the helper T cell to produce IL2, which aids in proliferation and differentiation of the B cell and also cytotoxic T cells
What doe a B cell do if it finds a microbe that has been opsonized by C3b?
the compliment protein directly stimulates B cell proliferation and differentiation into plasma cells without all of the other steps (no MHC, no T cell, etc.)
Describe the structure of an antibody (chains, regions, etc.)
heavy chain makes up the base Y, light chain adds a second line to the V part of the Y. Antigen binding sites are on the tips of the Y. The variable region is the V of the Y and is unique for the antigen this antibody binds to.
What are the 5 classes of antibodies? What are the classes based off of?
based on constant region
IgG, IgE, IgD, IgM, IgA
What percent of antibodies are IgG? What is special about them? What can all antibodies pass through?
75%
They can cross the placenta
All can cross through breast milk
Do antibodies destroy antigens? What do they do?
No
They neutralize, immobilize, agglutinate/precipitate, activate compliment, and enhance phagocytosis
What is neutralization?
block effects of toxins or prevent attachment to body cells
What is immobilization?
destroy the cilia or flagella that allow movement
What is agglutination/precipitation?
cross linking antigens to cause clumping which will allow them to be precipitated out
What is complement activation/enhancing phagocytosis?
by activating the complement system, a MAC is created in the antigen allowing for lysis and destruction/phagocytosis. They can also opsonize or agglutinate the antigen to allow phagocytosis to occur more easily.
What is the difference between primary and secondary B cell response? How does this occur?
primary - takes 7-10 days to reach peak antibody concentration
secondary - faster and more intense because memory cells can proliferate and result in exponential growth of the antibody concentration
What are two antibodies, one with lots of memory and one with very little memory?
IgG as lots, IgM has very little
