Transplant immunology Flashcards
What are the organs of the immune system?
Lymph nodes
Spleen
Thymus
What does MHA stand for?
Major histocompatibility antigen
What does MHC stand for?
Major histocompatibility complex
What is MHC?
A set of cell surface proteins essential for the adaptive immune system to recognise foreign molecules in vertebrates, which in turn determines histocompatibility.
What does HLA stand for?
Human Leucocyte Antigen
What is HLA?
Another name for MHC
What do MH proteins do?
They take samples from within infected cells to present on the cell surface so that T cells can see that the cell is infected.
Once they see this they can trigger the correct immune response
What are the two classes of MHC?
MHC I
MHC II
Which class of MHC displays antigens to CD8+ve cells?
MHC I
Which class of MHC displays antigens to CD4+ve cells?
MHC II
Which cells do MHC I present antigens to?
CD8+ve
Which cells do MHC II present antigens to?
CD4+ve
What are CD8+ve cells?
Cytotoxic T cells
What are CD4+ve cells?
T helper cells
What happens when an MHC protein presents an antigen to a T cell?
The T cell recognises a peptide bound to the MHC which activates the T cell
What do activated CD8+ve cells do?
T cytotoxic cells
Induce apoptosis of infected cell
What do activated CD4+ve cells do?
T helper cells
They help B cells make antibodies and produce cytokines
What do B cells do when they come across the transplanted organ? (if immunosuppressants were not being taken)
They internalise the non-self antigens on the transplanted cells and present them to the T cells
They also form immunological memory against these antigens
What do you need to ensure is matched before doing an organ transplant?
Blood group
MHC/HLA
What is cytotoxicity?
Killing/damaging/attacking the graft
List the responses that will occur against the transplant antigen.
(if immunosuppressants were not being taken)
- Innate immune response
- T cell mediated cytotoxicity
- Antibody mediated cytotoxicity
- ADCC
- Delayed type hypersensitivity
What is ADCC?
Antibody dependent cell-mediated cytotoxicity
Target cell is coated with antibody
Lymphocytes and lyse the antibody coated pathogen via the Fc regions binding with Fc receptors
Generally mediated by natural killer cells, but monocytes and eosinophils can also mediate ADCC
What are the 3 types of rejection?
- Hyperacute rejection
- Acute rejection
- Chronic rejection
In what cases would Hyperacute rejection take place? Why?
In ABO incompatibility and xeno-transplant
Because the person has pre-formed antibodies against the antigens in the graft
