lecture 37

Question 1

what is Severe Combined Immunodeficiency (SCID)?

Answer 1

• x-linked
• lack T and B cells

Question 2

what is Virus-induced immune suppression?

Answer 2

• viruses interfere with normal host immune system
• e.g measles, HIV

Question 3

how does HIV cause Virus-induced immune suppression?

Answer 3

HIV-receptor is CD4 molecule on CD4 T cells
- HIV targets and can kill CD4 T cells
- diminished levels of CD4 T
cells unable to provide “help” for antibody and cytotoxic responses
- HIV infection impacts on immunity to microbes (fungi,
bacterial and virus) and to cancer

Question 4

what is autoimmune disease?

Answer 4

• Normally prevented by host mechanisms of immune tolerance
• innate system can trigger
  autoimmunity or exacerbate autoimmunity
• mediated by the adaptive
  immune response

Question 5

what is immune tolerance?

Answer 5

• avoids autoimmunity
• thymus deletes autoreactive T cells
• Failures (due to your genes or triggering infection) in immune tolerance can lead to autoimmunity

Question 6

what is rheumatoid arthritis?

Answer 6

• autoimmune disorder that primarily affects joints
• Autoreactive T cells and B
  cells attack self-antigens
  present in the joints
• late onset

Question 7

how is type I diabetes caused?

Answer 7

Insulin beta-cells attacked. Other islet cells may escape autoimmune attack

Question 8

what is an allergic reaction?

Answer 8

• normally ‘harmless’ environmental antigens
• Chemicals can induce allergy (e.g. penicillin)
• range of outcomes

Question 9

how does an allergic reaction work (e.g peanut allergy)?

Answer 9

• DC present peptides from peanut proteins (allergens) to helper T cells
• Primed helper T cells activate B cells to secrete IgE
• Secreted IgE binds to mast cell receptors
• Binding of peanut proteins to FcR on mast cells triggers mast cell degranulation and release of
  histamine and other inflammatory mediators

Question 10

what are Fc receptors?

Answer 10

• bind to the Fc domain (on constant region) of antibody
• facilitate a number functions, including phagocytosis and mast cell activation

Question 11

what part of the antibody structure is rearranged in the bone marrow?

Answer 11

antigen binding site

Question 12

what part of the antibody structure is switched during immune response?

Answer 12

constant region

Question 13

what is the order that the constant region is changed?

Answer 13

IgM/D→IgG→IgA→IgE