Croatia Autoimmunity - Bizikova

Question 1

What scenarios can result in overproduction of an autoantigen?

Answer 1

• large amount of autoantigen released during inflammation or injury
• increasing amount of autoantigen in an aging body
• altered clearance of self-antigens (e.g. accumulation of apoptotic cells)

Question 2

What is the major target antigen of bullous pemphigoid?

Answer 2

BP180 (collagen XVII, NC16a)

Question 3

What is molecular mimicry?

Answer 3

possibility of sequence similarity or identity between self and non-self proteins
e.g. Strep A & cardiac myosin

Question 4

What is an epitope?

Answer 4

antigenic determinant on the surface of antigenic molecule to which a single antibody binds

Question 5

Why are animals with a thymoma more prone to autoimmune conditions?

Answer 5

• loss of central tolerance
• increased proliferation of thymocytes with an aberrant TCR expression recognizing self-antigens
• immature T cells lacking sufficient self-tolerance escape to the periphery

Question 6

Where does central tolerance take place?

Answer 6

thymus and bone marrow

Question 7

What is a cryptic epitope?

Answer 7

an epitope that is hidden or sequestered from recognition & presentation by immune cells

• physical barrier sequestering the epitope
• immune privilege site

Question 8

Why is a cryptic epitope less likely to induce tolerance?

Answer 8

limited ability to interact with immune cells (due to either a physical barrier or an immune privileged site)

Question 9

What is an event that could expose a cryptic epitope?

Answer 9

tissue injury & increased proteolysis
pro-inflammatory cytokine milieu at privileged site
increased expression of MHC and altered antigen presentation in tissues with limited to no MHC expression

Question 10

What is a superantigen?

Answer 10

doesn’t depend on MHC presentation to activate a lymphocyte

can stimulate up to 20% of all peripheral lymphocytes