Chapter 12 - Transplant Flashcards
Which HLA antigens are most important in recipient/donor matching?
HLA -A, -B, -DR (-DR most important overall)
ABO blood compatibility is not required for which transplant?
Liver
How is a crossmatch performed?
By mixing recipient serum with donor lymphocytes
What does a crossmatch detect?
Detects preformed antibodies; would generally cause hyperacute rejection
What is a panel reactive antibody (PRA)?
Technique identical to crossmatch; detects preformed recipient antibodies using a panel of typing cells
What can increase PRA?
Transfusions, pregnancy, previous transplant, autoimmune diseases
Treatment for mild rejection?
Pulse steroids
Treatment for severe or secondary rejection?
OKT3 or other drugs
1 malignancy following any transplant?
Skin cancer (squamous cell CA #1)
2 most common malignancy following transplant?
Posttransplant lymphoproliferative disorder (EBV-related)
Treatment for PTLD?
Withdrawal of immunosuppression; may need chemo/XRT for aggressive tumor. (This is the 2nd MC cancer in transplant, EBV related)
Mechanism of action of Azathioprine (Imuran)?
Inhibits de novo purine synthesis (which inhibits T cells); active metabolite is 6-mercaptopurine
Side effects of Azathioprine?
Myelosuppression; keeps WBC >3
Mechanism of action of steroids in anti-rejection?
Inhibit genes for cytokine synthesis (IL-1, IL-6) and macrophages
Mechanism of cyclosporin (CSA)?
Binds cyclophilin protein and inhibits genes for cytokine synthesis (IL-2, IL-3, IL-4, INF-gamma)
Side effects of cyclosporin (CSA)?
Nephrotoxicity, hepatotoxicity, HUS, tremors, seizures
Mechanism of action of FK-506 (Prograf, tacrolimus)?
Binds FK-binding protein; similar to CSA but 10-100x more potent
Side effects of Prograf (FK-506, tacrolimus)?
Nephrotoxicity, mood changes, more GI and neurological side effects than CSA
Mechanism of action of ATGAM?
Equine polyclonal antibodies directed against antigens on T cells (CD2, CD3, CD4, CD8, CD11/18)
What is ATGAM used for?
Induction therapy
ATGAM is dependent on what to work?
Complement dependent
Mechanism of action of thymoglobulin?
Rabbit polyclonal antibody; similary action as ATGAM, causes rapid T-cell depletion
Mechanism of action of OKT3?
Monoclonal abs that block antigen recognition function of T cells by binding CD3, inhibiting T cell receptor complex; causes CD3 opsonization that is complement dependent
What is OKT3 used for?
Severe rejection
Side effects of OKT3?
Fever, chills, pulmonary edema, shock
Mechanism of action of Zenapax (Daclizumab)?
Human monoclonal ab againsst IL-2 receptors
When is Zenapax (Daclizumab) used?
Used with induction and to treat rejection
What is the timeframe and cause of hyperacute rejection?
Within minutes to hours; caused by preformed antibodies that should have been picked up by the crossmatch; activates complement cascade and thrombosis of vessels occurs
Treatment of hyperacute rejection?
Emergent retransplant
What is accelerated rejection?
(<1 wk) Caused by sensitized T cells to donor antigens; produces secondary immune response
Treatment for accelerated rejection?
Increased immunosuppression, pulse steroids, possibly OKT3
What is the timeframe and causative agent of acute rejection?
1wk to 1month; caused by T cells (cytotoxic and helper T cells)
Treatment of acute rejection?
Increased immunosuppression, pulse steroids, possibly OKT3
What is the timeframe and cause of chronic rejection?
Months to years; Type IV hypersensitivity reaction (sensitized T cells); Ab formation also plays a role, leads to graft fibrosis and vascular damage
Treatment of chronic rejection?
Increased immunosuppression, OKT3 - no really effective treatment
How long can a kidney be stored?
48 hours
What is the mortality following kidney transplant from?
Stroke and MI
Can a kidney from a patient with a UTI or acute increase in Cr (1.0-3.0) still be used?
YES
Transplanted kidney is grafted to what vessel?
Iliac vessels
1 complication following kidney transplant?
Urine leak