Transplantation Immunology Flashcards
A transplant from the same individual (ex: skin graft).
- autograft
A transplant from an identical twin (or inbred lab mice).
- isograft
A transplant from a member of the same species.
- allograft
- (most common type of transplant)
A transplant from a different species.
- xenograft
What are the tissue type and genetic identity of an autograft transplant?
- tissue type: autologous
- genetic identity: total
What are the tissue type and genetic identity of an isograft transplant?
- tissue type: isologous
- genetic identity: isogenic
What are the tissue type and genetic identity of an allograft transplant?
- tissue type: homologous
- genetic identity: allogenic
What are the tissue type and genetic identity of a xenograft transplant?
- tissue type: heterologous
- genetic identity: xenogenic
What are the three classes of transplant antigens?
- ABO blood groups, MHC antigens (HLA), and minor histocompatibility antigens
Give an example of a minor histocompatibility antigen.
- proteins coded by genes on a Y chromosome that are not found in females
Where are the MHC/HLA genes found?
- chromosome 6
How many classes of MHC/HLA are there? What does each do?
- THREE classes!
- type I: found on all nucleated cells; present to CD8+
- type II: found on professional APCs: present to CD4+
- type III: do not code for MHC antigens; code for other proteins with immune functions
What are the different types of MHC class I? Class II?
- class I: HLA-A, HLA-B, HLA-C
- class II: HLA-DP, HLA-DQ, HLA-DR
Which types of MHC are most important for renal transplant success?
- HLA-DR, HLA-B, and HLA-A (in that order)
What are the three types of transplant rejection? Which is most commonly encountered?
- hyperacute, acute, and chronic
- acute rejection is most common
Hyperacute Rejection
- occurs within minutes or hours of the transplant
- a result of pre-existing antibodies to the donor’s blood or MHC antigens (it’s essentially a secondary immune response)
Is Hyperacute Rejection responsive to immuno-suppressive therapy?
- no, because the antibodies are already in the host’s body
Acute Rejection
- occurs within 1 to 3 weeks of the transplant
- is a primary immune response to the donor tissue
- two types (direct and indirect)
Is Acute Rejection responsive to immuno-suppressive therapy?
- yes, because the antibodies against the transplant have not yet been created (the body needs to mount a successful primary immune response in order for rejection to occur)
Direct Acute Rejection
- 1 of 2 types of acute rejection
- when the donor’s APCs migrate to the host’s lymph nodes and stimulate T-cells directly
Indirect Acute Rejection
- 1 of 2 types of acute rejection
- when the recipient’s APCs process and present the donor’s antigens to T-cells
Chronic Rejection
- occurs months to years after the transplant
- difficult to detect
- more common in young people (perhaps because of their stronger immune systems)
Is Chronic Rejection responsive to immuno-suppressive therapy?
- usually no
Graft V. Host (GVH) Reaction
- when cells from the DONOR respond to and attack the HLA antigens of the recipient
- occurs when mature T cells are injected into a non-identical immunocompromised recipient
