CCTC - Certified Clinical Transplant Coordinator Transplant Immunology and Pharmacology Questions and Answers — Questions and Answers
Question 1: A kidney transplant recipient, 6 months post-transplant on a standard triple-drug regimen, presents with new-onset tremors, headache, and a random blood glucose of 215 mg/dL. Which medication is the most likely cause of this constellation of symptoms?
- Mycophenolate Mofetil
- Prednisone
- Tacrolimus (Correct answer)
- Azathioprine
Correct answer: Tacrolimus
Tacrolimus, a calcineurin inhibitor, is well-known for causing both neurotoxicity (presenting as tremors and headaches) and post-transplant diabetes mellitus (hyperglycemia). While prednisone can also cause hyperglycemia, the combination with significant new-onset neurological symptoms strongly points towards tacrolimus toxicity. Mycophenolate's primary side effects are gastrointestinal and hematologic, while azathioprine is associated with bone marrow suppression.
Question 2: The presence of C4d deposits in the peritubular capillaries on a renal allograft biopsy is a key histopathological finding for which type of rejection?
- Hyperacute rejection
- Antibody-mediated rejection (AMR) (Correct answer)
- T-cell mediated rejection (TCMR)
- Chronic allograft nephropathy
Correct answer: Antibody-mediated rejection (AMR)
C4d is a component of the classical complement cascade. Its deposition in the peritubular capillaries indicates that donor-specific antibodies have bound to the graft endothelium and activated the complement system, which is the defining pathogenic mechanism of antibody-mediated rejection (AMR). T-cell mediated rejection is characterized by tubulitis and interstitial inflammation, not C4d staining.
Question 3: A transplant candidate has a calculated Panel Reactive Antibody (cPRA) of 98%. What is the primary clinical implication of this value?
- The candidate has a 98% chance of developing acute rejection.
- The candidate is immunologically sensitized to antigens present in 98% of the donor pool. (Correct answer)
- The candidate's immune system is suppressed and will require less induction therapy.
- The candidate has pre-existing antibodies against only two specific HLA antigens.
Correct answer: The candidate is immunologically sensitized to antigens present in 98% of the donor pool.
The cPRA estimates the percentage of deceased donors that a candidate will be incompatible with due to the presence of pre-formed HLA antibodies. A cPRA of 98% indicates the candidate is highly sensitized, making it extremely difficult to find a compatible (negative crossmatch) donor. It signifies a major immunological barrier to transplantation, not a direct probability of rejection post-transplant.
Question 4: Which of the following immunosuppressive agents is a monoclonal antibody that functions by blocking the CD25 subunit of the IL-2 receptor on activated T-lymphocytes, thereby preventing their proliferation?
- Antithymocyte Globulin
- Rituximab
- Alemtuzumab
- Basiliximab (Correct answer)
Correct answer: Basiliximab
Basiliximab is an IL-2 receptor antagonist. It specifically binds to the CD25 alpha chain of the IL-2 receptor on activated T-cells, which competitively inhibits IL-2 mediated T-cell activation and proliferation. Antithymocyte Globulin is a polyclonal antibody that depletes T-cells. Rituximab targets CD20 on B-cells, and Alemtuzumab targets CD52 on both T- and B-lymphocytes.
Question 5: A liver transplant recipient who is stable on a sirolimus-based regimen is admitted for poor wound healing and a new-onset, significant leg edema. Laboratory results show 4+ proteinuria. These findings are most characteristic of the side-effect profile of which drug class?
- Calcineurin inhibitors (CNIs)
- Corticosteroids
- mTOR inhibitors (Correct answer)
- Antimetabolites
Correct answer: mTOR inhibitors
Sirolimus is an mTOR inhibitor. This class of drugs is known to cause impaired wound healing, peripheral edema, and significant proteinuria. While CNIs can be nephrotoxic, the combination of poor wound healing and heavy proteinuria is a classic presentation of mTOR inhibitor side effects. Corticosteroids can cause fluid retention but not typically this degree of proteinuria and wound impairment. Antimetabolites are not associated with these specific effects.
Question 6: The primary mechanism of action for mycophenolate mofetil (MMF) involves the non-competitive and reversible inhibition of which enzyme, leading to impaired lymphocyte proliferation?
- Calcineurin
- Cyclooxygenase-2 (COX-2)
- Inosine monophosphate dehydrogenase (IMPDH) (Correct answer)
- Dihydrofolate reductase
Correct answer: Inosine monophosphate dehydrogenase (IMPDH)
Mycophenolate mofetil is a prodrug of mycophenolic acid (MPA). MPA selectively, non-competitively, and reversibly inhibits inosine monophosphate dehydrogenase (IMPDH). This enzyme is crucial for the de novo pathway of guanosine nucleotide synthesis, which is essential for the proliferation of T and B lymphocytes. By blocking this pathway, MMF effectively reduces lymphocyte proliferation.
CCTC - Certified Clinical Transplant Coordinator Transplant Immunology and Pharmacology Questions and Answers
A kidney transplant recipient, 6 months post-transplant on a standard triple-drug regimen, presents with new-onset tremors, headache, and a random blood glucose of 215 mg/dL.
Which medication is the most likely cause of this constellation of symptoms?