Graft rejection: major histocompatability complex (MHC)

Question 1

What are the different types of antigen presenting cells?

Answer 1

• Dendritic cells
• Macrophages
• B cells

Question 2

What do class 3 genes of the MHC in humans encode for?

Answer 2

Complement, cytokines & enzymes

Question 3

What are the features of the MHC that make it difficult for pathogens?

Answer 3

• The MHC gene is polygenic
• MHC gene is polymorphic
• Means that every individual expresses a number of different MHC antigens
• Each MHC will be capable of presenting a different range of peptides

Question 4

What are autografts?

Answer 4

tissue transplanted from one site to another on the same person

Question 5

What are isografts?

Answer 5

Same, grafts between genetically identical individuals

Question 6

What are xenografts?

Answer 6

Foreign, grafts taken from another animal species.

Question 7

What are allografts?

Answer 7

Tissue taken from an individual in the same species but who is genetically different- most common

Question 8

What is the main cause of graft rejection?

Answer 8

Transplanted organs from donors bearing MHC molecules that differ from the recipient can be rejected because there are a large number of t-cells that react to the allogenic MHC

Question 9

Define alloreactivity

Answer 9

The recognition of peptides complexed with non-self MHC

Question 10

What is GvHD (Graft vs Host Disease)?

Answer 10

Where donor leucocytes infiltrate & attack recipient tissues- can cause exudative skin lesions

Question 11

How can GvHD be beneficial?

Answer 11

It can remove residual cancer