MHC - week 6 PBL

Question 1

What is the role of Major Histocompatibility complex in immune tolerance?

Answer 1

MHC = glycoproteins that control how the immune system detects and responds to specific antigens

Question 2

How does MHC allow pathogen recognition?

Answer 2

MHC present peptides normally inside the cell to immune system so it can present to T cells

T-cells are activated if MHC peptide recognised as foreign

T cell activation leads to B cell activation

Question 3

What is immune tolerance?

Answer 3

recognition of self antigens to avoid the immune system from attacking itself

Question 4

Where are MHC proteins in order to present themselves to immature T cells?

Answer 4

Epithelium of thymus

Question 5

Name the two immunological tolerance mechanisms

Answer 5

Central and peripheral

Question 6

Describe central immunological tolerance

Answer 6

eliminates self-reactive lymphocytes in bone marrow and thymus

1) positive selection –> immature T cells have weak binding for MHC = survival

2) negative selection –> immature T cells have strong binding for MHC = death

Question 7

Describe peripheral immunological tolerance

Answer 7

Eliminates self-reactive lymphocytes that escape the radar of central mechanisms

Occurs in peripheral tissues and lymphoid organs

Question 8

What is autoimmunity?

Answer 8

state where body attacks own tissues/organs

Question 9

What is one cause of autoimmunity?

Answer 9

A breakdown in tolerance to either endogenous (in thymus) or environmental (peripheries) antigens

Question 10

How can HLA alleles result in autoimmunity?

Answer 10

Inherit an HLA allele that binds poorly to self-antigen in thymus and allows self-tolerance

Certain HLA alleles linked to autoimmune diseases

Question 11

What is environmental autoimmunity?

Answer 11

When self-reactive T cells escape the periphery leading to the production of antibodies by B-cells to self-antigens