PSIO202 Exam 2 Lecture 19

Question 1

How does a b cell acquire its receptor/antibody?

Answer 1

random genetic mutation

Question 2

What happens when an antigen binds to the antigen receptor on a b cell?

Answer 2

the b cell is activated and produces plasma cells

Question 3

What do plasma cells do?

Answer 3

produce free antibodies with the same receptor as the one’s which were on the surface of the b cell

Question 4

At what location do antibodies fight pathogens?

Answer 4

in the ISF and extracellular fluid

Question 5

Do B cells leave the lymphatic system?

Answer 5

No, just the antibodies

Question 6

What are the 4 steps of antibody mediated immunity?

Answer 6

recognition, activation, proliferation/differentiation, and killing

Question 7

Explain the b cell process of recognition and activation?

Answer 7

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.

Question 8

Unlike T cells which can only see microbes when their peptides are presented on an MHC, B cells can see…

Answer 8

epitopes on many kinds of large molecules

Question 9

How many antibodies per hour can be secreted by a plasma cell?

Answer 9

100 million per hour

Question 10

How long can memory B cells remain in the body?

Answer 10

20+ years

Question 11

What are the co-stimulators when a helper T cell binds to the MHC2 on a b cell?

Answer 11

CD4 and IL B7

Question 12

What does IL B7 do during B cell activation?

Answer 12

it stimulates the helper T cell to produce IL2, which aids in proliferation and differentiation of the B cell and also cytotoxic T cells

Question 13

What doe a B cell do if it finds a microbe that has been opsonized by C3b?

Answer 13

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.)

Question 14

Describe the structure of an antibody (chains, regions, etc.)

Answer 14

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.

Question 15

What are the 5 classes of antibodies? What are the classes based off of?

Answer 15

based on constant region
IgG, IgE, IgD, IgM, IgA

Question 16

What percent of antibodies are IgG? What is special about them? What can all antibodies pass through?

Answer 16

75%
They can cross the placenta
All can cross through breast milk

Question 17

Do antibodies destroy antigens? What do they do?

Answer 17

No
They neutralize, immobilize, agglutinate/precipitate, activate compliment, and enhance phagocytosis

Question 18

What is neutralization?

Answer 18

block effects of toxins or prevent attachment to body cells

Question 19

What is immobilization?

Answer 19

destroy the cilia or flagella that allow movement

Question 20

What is agglutination/precipitation?

Answer 20

cross linking antigens to cause clumping which will allow them to be precipitated out

Question 21

What is complement activation/enhancing phagocytosis?

Answer 21

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.

Question 22

What is the difference between primary and secondary B cell response? How does this occur?

Answer 22

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

Question 23

What are two antibodies, one with lots of memory and one with very little memory?

Answer 23

IgG as lots, IgM has very little