Flashcards in Overview of Organ Transplantation Deck (16)
What is the culprit of hyperacute rejections?
Pre-existing circulating antibodies specific for graft antigens
How does inflammation occur in hyperacute rejection?
Antibodies bind and activate complement causing inflammation
Why do xenograft cells cause complement activation?
They do not have regulatory proteins able to inhibit complement activation
What cells are responsible for acute rejections?
What cells are responsible for chronic rejections?
What does acute rejection cause?
What does chronic rejection cause?
Concentric thickening of the vessels wall causing occlusion
What is direct allorecognition?
Donor dendritic cells (transferred inside the organ) present to the recipients T cells
What is indirect allorecognition?
Recipients own dendritic cells present to the recipients T cells
Two possible ways a T cell will recognized an allogeneic MHC molecule and think it's self?
1.) T cell recognizes the allogeneic MHC molecule whose structure resemble a self MHC + foreign peptide complex
2.) T cell recognizes structure formed by both the allogeneic MHC molecule and bound peptide
What occurs mainly in acute rejection?
Alloantibodies mainly damage graft vasculature
What occurs mainly in chronic rejection?
Alloantibodies mainly damage endothelial cells
What are minor histocompatibility antigens?
Non-MHC antigens but proteins that differ in allelic form such as blood cells that are seen as antigen in another person's body
When does a graft versus host disease occur?
When mature allogeneic T cells or their precursor are transplanted into a recipient
What occurs in a GVHD?
Transferred allogeneic T cells recognize recipient alloantigens and attack recipient tissues