Lecture 8 - Immunological Tolerance and Autoimmune Disease (Powell)

Question 1

Where does central tolerance occur?

Answer 1

bone marrow and thymus

Question 2

Central tolerance involves…

Answer 2

immature lymphocytes recognizing self antigen

Question 3

Peripheral tolerance involves…

Answer 3

mature self-reactive lymphocytes (that somehow escaped central tolerance)

Question 4

Positive selection happens in…

cells can’t recognize MHC & are deleted

Answer 4

CORTICAL region of thymus

Question 5

Negative selection happens in…

cells bind antigen too tightly & are deleted

Answer 5

MEDULLARY region of thymus

Question 6

What Ig do immature B cells express?

Answer 6

IgM

Question 7

Mechanisms of Peripheral Tolerance

Answer 7

1. Clonal deletion/apoptosis
2. Clonal anergy (functionally inactivated)
3. Supression of these self-reactive T cells by interaction with other cells
4. Ignorance (cells don’t respond to antigen)

Question 8

B cells can undergo FOLLICULAR EXCLUSION (a type of peripheral tolerance.

Answer 8

They are excluded from enter the follicle of the speen, a very enriching area that B cells need to develop.

Question 9

self-reactive B cells enter a state of anergy when T cells see the antigen, but they don’t respond w/ costimulatory molecule (CD40L/CD40 interaction) because the antigen is SELF and therefore the B cell does not become activated

Answer 9

okay.

Question 10

Which two receptors are on a T cell?

Answer 10

CD28 (activate T cell)

CTLA-4 (shut T cell down)

Question 11

What do CD28 and CTLA-4 bind to?

Answer 11

B7 on APCs

Question 12

Which has higher affinity for B7, CD28 or CTLA-4?

Answer 12

CTLA-4 (T cell inhibitory costimulator)

Question 13

What happens if no IL-2 is present?

Answer 13

T cell apoptosis. They NEED IL-2.

Question 14

Oral administration of Ag _____ tolerance

Answer 14

favors

Question 15

Subcutaneous Ag favor _____

Answer 15

immune responses