Solid Organ Transplant Flashcards
What is the pathophysiology behind organ transplant rejection?
Our body does not recognize the foreign organ so the antigen-presenting cells of the organ present its antigen (HLA) to both CD4 and CD8 cells. This triggers T cell proliferation where MHC 1 activates the cytotoxic CD8 cells to cause allogenic cell lysis. The CD4 cells “help” to stimulate B cell immunity which then produces antibodies that trigger the inflammatory response. This antibody production also causes graft cell cytotoxicity.
What is HLA?
Human leukocyte antigen is MHC that is found in humans and is the target response cell for transplant organ rejection. This is why it is crucial to make sure the HLA matches for donor and recipient prior to organ transplantation.
What is HLA B27?
People with HLA B27 antigen are at higher risk of developing ankylosing spondylitis.
What are calcineurin inhibitors?
Cyclosporine and tacrolimus. This drug class prevents cytokine production by binding calcineurin because this is what regulates cytokine production. without enough levels of cytokines, T-cell activation cannot occur. This drug has no effect on T cells that have already been activated so these medications can only help to prevent rejection.
What are corticosteroids?
Prednisone and methylprednisolone. They prevent RNA and DNA synthesis, cytokine release, action of macrophages, and T and B cell activity. These medications inhibit the immune and inflammatory response. They can be used to treat rejection.
What is azathioprine?
Azathioprine is a purine antagonist. This is important because purines are one of the nucleotides that are required for DNA and RNA which then leads to DNA replication and causes cell division. A purine antagonist can prevent the growth of DNA and cell division within the T cell. This medication can only be used to prevent rejection.
What is mycophenolate mofetil?
Inosine monophosphate is a molecule used to make DNA and RNA because once it is converted to xanthosine monophosphate, it becomes a precursor to guanosine compounds which is one of the molecules that are required for DNA and RNA synthesis. Mycophenolate inhibits the action of inosine monophosphate and thus limits DNA and RNA synthesis. This can only be used to prevent rejection.
