Chapter 17 Terms (Transplantation) Flashcards
Codominance
Genes are expressed whether present as a single copy (heterozygous or hemizygous) or two copies (homozygous)
Orthotopic Grafts
With respect to location, tissues or organs that are placed in their normal anatomic location.
Heterotopic Grafts
Grafts that are placed into a site other than their normal place
Autografts
Those transferred from one part of an individual to another location on the same individual
Syngeneic Grafts
Those transferred between individuals who are genetically identical or nearly so (eg, identical twins or members of imbred strain)
Allogeneic Grafts (Allografts)
Transferred between two genetically disparate individuals of the same species (eg, brother & sister, paretn & child, or totally unrelated individuals)
Xenogeneic Grafts (Xenografts)
Those exchanged between members of different species (eg, the placement of primate heart in to a human recipient)
Laws of Transplantation
Originally established in experiment studies, particularly in mice, but are applicable to human transplantation as wel.
Imbreeding
Accomplished by mating of closely related individuals
Inbred Strains
When laboratory mice are subjected to borther-sister mating for 20 or more consecutive generations
Congenic Strains
Permit comparisons among organisms that differ from one another by only a small chromosomal segment in common
Direct Recognition
Can occur only when some of the MHC class I or II molecules on the donor cells are identical to those on the recipient
Indirect Recognition
Occurs when recipient APCs process & present peptide fragments derived from the ingestion, processing, & presentation of cellular debris from donor cells - debris that contains the donor histocompatibilty antigens - & presents it to recipient T cells.
Chronic Rejections
- (Slowest & Least Vigorous)
- Transplanted tissues or organs establish a vascular connection & proceed to function for weeks, months, & even years before signs of deterioration due to immune attack becomes evident
Acute Rejection
- (Occur much sooner after the graft emplacement than do chronic rejections)
- Grafts establish vascular connections & function normally for a relatively short period (2-4 weeks) before first signs of rejection appear
Hyperacute Rejection
- (Most rapid)
- They are initiated & completed within a few days of graft replacement, usually before the grafted tissue or organs can establish vascular connections
Second Set Rejection
Attempts to repeat grafts that have previously been rejected usually result in an accelerated graft rejection.
Specific Immune Tolerance
Involves a selective inhibiting of the responsiveness to a given antigen or set of antigens
Immune Suppression (Immunosuppression)
Involves inhibiting general immune responsiveness without regard to the specificity
Transfusion
The transplantation of blood
ABO Antigen System
A set of carbohydrate structures on RBCs surfaces & even some endothelial & epithelial cells
Natural Antibodies (Naturally Occuring Antibodies)
Recognize & bind A & B antigens
Transfusion Reaction
Massive destruction of RBCs
Rh (“Rhesus”) Antigens
- Proteins on RBC surfaces
- When an RH- individual is exposed to Rh+ RBCs, he or she can generate antibodies, some of which are of the IgG isotype
Hemolytic Disease of the Newborn (HDN)
- Also called Erythroblastosis Fetalis
- An alloimmune condition that develops in a fetus, when the IgG molecules produced by the mother pass through the placenta.
- Some of these antibodies attack the fetal RBCs
Gaft-vs-Host Diseases (GVHD)
- Common complication following an allogeneic tissue transplant.
- Commonly associated with stem cell or bone marrow transplant.
