MHC and transplant rejection Flashcards
What does HLA mean
Human Leukocyte antigens
Class 1 HLA’s
all cells except red blood cells - beta pleated sheet + 2 alpha helices
Class 2 HLA’s
APC’s - alpha + beta chain
Class 1 HLA role in immune response
- pick up/process peptides from intracellular organisms
Class 2 HLA role in immune response
- Process peptides that have been endocytosed and presented on surface
What are the benefits and negatives of MHC genes becoming HLA milecules
Benefits - Help fight pathogens
Negative - More susceptible to autoimmune diseases and can cause transplant rejection
How can a T cell respond to an antigen
A T cell will only recognise and respond to a foreign antigen if it is bound to an MHC molecule
First successful transplantation
Herrick brothers- Boston 1954
What is allogeneic transplantation
Transplant that occurs in people that are not related
The aim of allogeneic transplantation
Best match as possible + immunosuppression
What happens to APC’s during transplant
APC migrate to lymph nodes where they are recognised
The immunological synapse
The interaction between APC’s and lymphocytes
- Immunosuppressive agents act in the synapse
Transplant rejection
- CD4 cells cause effector pathway
- combination of antibody production, cytotoxic and delayed hypersensitivity reaction
How is HLA typed
- one allele from mum one from dad
- Extraction of DNA, amplification and detection of sequence polymorphisms
- Less mismatching = more graft survival
Process for transplant
- HLA typed and confirmed fit for transplant
- Organ screened for antibodies vs HLA
- tissue types cross matched
- Add tissue to patient serum and see if there is any cell lysis
