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Question 1

What are T cells?

Answer 1

lymphocytes that recognize MHC antigens on the surface of cells

Question 2

How are T cells selected in the thymus?

Answer 2

positively: binding of thymus epithelium gets selected for
negatively: too much affinity for self-MHC

Question 3

What are the accessory molecules involved with T cell activation?

Answer 3

CD4 - helper T

CD 8 - cytotoxic T

Question 4

CD 28 binding with B7 on APC does what?

Answer 4

stabilizes and strengthens activation triggered by TCR binding

Question 5

CTLA4/CD152 binds with B7 to do what?

Answer 5

downregulates response; controls activation achieving a homeostasis

Question 6

What is allograft rejection?

Answer 6

immune mediated graft injury; often defined by time or mechanism (cellular, immune)

Question 7

Chronic rejection

Answer 7

slow, inefficient
dysregulated repair
ddx: recurrent dz

Question 8

Rejection can be multifactorial:

Answer 8

T cell, antibody, cytokine

Question 9

Naive cells require what to cause an effective rejection reaction?

Answer 9

Lymphoid tissue (memory cells do not)

Question 10

What is heterologous immunity?

Answer 10

Immunity to one antigen can confer immune reactions to other antigens

Question 11

Trauma can increase naive T cell conversion to memory T cell. What does this mean for the surgeon?

Answer 11

Surgical technique can affect transplant rejection.

Question 12

How does antibody mediated rejection cause injury?

Answer 12

antibodies to donor antigens cause inflammatory reaction and coagulation (hyperacute rejection; should be screened for)

Question 13

What is the centerpoint of multiple means of complement activation?

Answer 13

C3

Question 14

What is the direct product of C3 convertase?

Answer 14

C5