Transplantation Flashcards
When is a transplant rejected?
when foreignness is detected
How is organ transplantation possible?
immunosuppressive therapy
Why is blood transfusions possible?
• Red blood cells do not express major
histocompatibility complex (MHC) antigens.
• Limited number of red blood cell antigens
(ABO, Rh).
• Matching is straight forward and effective.
In humans what is the major histocompatibility complex (MHC) encoded by?
HLA
What is an autograft?
self to self, accepted
What is an isograft?
identical twin to twin, accepted
What is an allograft?
person to person (not identical twins), variable degree of rejection
What is a xenograft?
species to species, strong rejection
What are some grafts rejected?
• T cells are responsible for recognising “non-
self” antigens on transplanted cells or tissues.
• Can be cell mediated rejection or antibody
mediated.
• Skin grafts from other donor (allogenic) last around 2 weeks.
• Other transplants (eg. Kidney) can be rejected
after years.
What is histocompatibility?
compatibility between the tissues of different individuals, so that one
accepts a graft from the other
without giving an immune reaction
What is tissue typing?
allows donors to be match to recipients with similar HLA “fingerprints”.
When is tissue typing particularly important?
bone marrow
transplants.
How does tissue typing work?
Polymerase chain reaction (PCR) used to
detect changes down to single amino acids.
What is the cross match test?
Recipient serum potentially containing donor-specific anti-HLA antibodies is added to donor T or B lymphocytes, along with complement (A). If donor-specific antibodies are not present, no lysis occurs and the result is deemed negative (B). If donor-specific anti-HLA antibodies bind to the lymphocytes and then activate complement, cell lysis will occur and the crossmatch result will be deemed positive (C).
What is acellular immune activation?
Biomaterials are able to activate the immune
response without cells
• In particular naturally derived materials with
biological ligands
• Can activate both innate and acquired
immune responses
