PBL Block 4

Question 1

What is chronic rejection?

Answer 1

Delayed hypersensitivity after 6 months. Graft MHC’s and antigens trigger type 4 hypersensitivity, driven by CD8+ T cells

Question 2

How do T cells interact with the TCR?

Answer 2

They recognise the MHC complex rather than the antigen.

Question 3

What is acute rejection?

Answer 3

1 week-> 3 months after transplant which can be a type 4 hypersensitivity for CD8 cells

Question 4

What is hyperacute rejection?

Answer 4

Type 2 hypersensitivity reaction to blood transfusion or organ transplant which activates the complement system. Causes endothelial damage and thrombosis

Question 5

How does graft rejection occur?

Answer 5

CD8+ T cell mediated when chronic or antibody/complement mediated in acute

Question 6

What are the stages of HIV?

Answer 6

Acute HIV, Chronic HIV (latency which is symptomatic) and AIDS.

Question 7

What does HIV do in the body?

Answer 7

HIV utilises integrase to insert viral DNA into host chromosomal DNA and reverse transcriptase generates transcripton of viral proteins.

Question 8

What is central tolerance?

Answer 8

Eliminating any developing T or B lymphocytes that are autoreactive to self cells.

Question 9

How do B cells develop?

Answer 9

Precursor-> pro B cells-> pre-B cell r no cell surface immunogoblin -> immature B cell which matures in the red bone marrow. It then migrates to enter the lymph node/spleen.

Question 10

What is positive selection?

Answer 10

Signalling through the antigen receptor for cell with MHC to survive.

Question 11

Which cells undergo negative and positive selection?

Answer 11

Both B and T cells undergo positive and negative selection in the primary lymphoid organs