Transplantation and Immunosuppressive Drugs Flashcards
(56 cards)
What is the definition of transplantation?
β The introduction of biological material (organs, tissues, cells) into an organism
What is an autologous transplant?
β transplantation of tissue from one part of the organism to another part of the same organism
What is an example of an autologous transplant?
β Skin graft
What is a syngeneic transplant?
β donor material transplanted into the recipient when the donor and recipient are genetically identical
What is an allogenic transplant?
β Donors and recipients are from the same species but genetically different
What is a xenogenic transplant?
β donor and recipient are different species
What are immune responses to transplant caused by?
β genetic differences between the donor and recipient
What are human MHC proteins called?
β human leukocyte antigen
On what chromosome is HLA found?
β chromosome 6
How many MHC Class I alleles are there?
β 3
β A, B, C
How many MHC Class II alleles are there and what structures do they form?
β 3
β heterodimers of two proteins
Which cells in the body express both MHC class I and II?
β White blood cells
What are the MHC Class II alleles?
β DRA β DRB β DPA β DPB β DQA β DQB
What is needed to define epitopes on HLA?
β next generation sequencing
What do T cells recognise?
β short peptide fragments that are presented to them by MHC proteins
What can professional APCs do with external proteins?
β internalise them and cross present them on the MHC class I pathway
What does MHC class II bind?
β Fragments of proteins which have been taken up by endocytosis
What does MHC Class I bind?
β Fragments of intracellular proteins
What is the function of CLIP?
β Maintains the shape of the HLA until the peptides are ready to bind
Describe indirect allo-recognition?
β The recipient cell has self HLA on its cell if the cell expresses the self peptide as normal cells do there is no immune response
β the TCR will be quiescent
β When self HLA presents a peptide (eg influenza peptide) an immune response will occur against the influenza
β if the recipient has a transplantation and the self HLA can present a peptide from the donor HLA molecule there is indirect allo-recognition
What is indirect allo-recognition?
β TCR of recipient detecting non-self peptide on self HLA
Describe direct allo-recognition?
β A recipient has transplanted tissue which contain donor immune cells
β If they have been perfectly matched the donor HLA is the same as the recipient HLA and there is no reaction
β when there is an unmatched donor there is direct allo-recognition
β the TCR from the recipients T cells will detect the MHC
β even if the peptide isnβt recognised as foreign (because it is from a conserved region) the unmatched HLA activates the T cells
What is direct allo-recognition?
β TCR of the recipient reacting to donor HLA molecules
How many MHC loci are usually matched?
β 4/6 MHC class II loci
