Complications of Transplantation

Complications of Transplantation

Complications of Transplantation

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Transplant Rejection - Attack of the Clones

  • Recipient's immune system attacks donor alloantigens (MHC/HLA).
  • Types & Timing (📌 Mnemonic: Hot Apple Crumble):
    • Hyperacute Rejection:

      • Minutes to hours.
      • Cause: Pre-formed anti-donor antibodies (e.g., ABO, anti-HLA Class I).
      • Mechanism: Type II Hypersensitivity. Results in complement activation, endothelial damage, thrombosis, graft necrosis.
    • Acute Rejection:

      • Days to weeks (usually <6 months); most common type.
      • Cellular: CD8+ T-cells (cytotoxic) directly damage graft; CD4+ T-cells (helper) mediate inflammation. Type IV HSR.
      • Humoral: Anti-donor antibodies (de novo or anamnestic) target graft vasculature. Type II HSR.
    • Chronic Rejection:

      • Months to years. Often irreversible, leading to progressive graft failure.
      • Mechanism: Complex; involves cellular and humoral immunity, cytokines, growth factors.
      • Pathology: Vascular changes (graft arteriosclerosis), interstitial fibrosis, parenchymal atrophy.
  • Diagnosis: Graft biopsy is the gold standard.
  • Prevention: HLA matching, immunosuppressive drugs.

⭐ Acute cellular rejection, primarily mediated by T-lymphocytes, is the most common form of rejection and is often reversible with increased immunosuppression.

Post-Transplant Infections - Bugs on Board

Post-transplant infections impact outcomes. Timing reveals likely pathogens. Immunosuppression level is key.

Post-transplant infections by time and type

  • Common Pathogens & Concerns:
    • CMV: Pneumonitis, GI disease, hepatitis. Prophylaxis/pre-emptive therapy common.
    • PJP: Interstitial pneumonia. TMP-SMX prophylaxis.
    • Aspergillus: Invasive pulmonary disease, high mortality.
    • BK Virus: Polyomavirus nephropathy in renal transplants.
  • Key Prophylaxis Durations:
    • PJP: TMP-SMX for 6-12 months.
    • CMV: Valganciclovir/Ganciclovir for high-risk (D+/R-), typically 3-6 months.
    • Fungal (Candida): Fluconazole for early post-op period.
    • HSV/VZV: Acyclovir/Valacyclovir if seropositive.

⭐ CMV is the most common opportunistic infection in Solid Organ Transplant (SOT) recipients, typically occurring 1-6 months post-transplant, causing fever, leukopenia, or organ-specific disease.

Drug Side Effects & PTLD - Pills & Perils

  • Calcineurin Inhibitors (CNIs): Nephrotoxicity, neurotoxicity, HTN, hyperglycemia.
    • Cyclosporine: 📌 "Cyclo Spor Hirsute Gums" (Hirsutism, Gingival hyperplasia).
    • Tacrolimus: Alopecia, ↑diabetes risk.
  • Antiproliferatives:
    • Mycophenolate (MMF): GI upset (diarrhea), leukopenia.
    • Azathioprine: Myelosuppression, pancreatitis.
  • mTOR Inhibitors (Sirolimus, Everolimus):
    • Hyperlipidemia, impaired wound healing, mouth ulcers, pneumonitis.
  • Corticosteroids:
    • Cushingoid features, hyperglycemia, osteoporosis, ↑infection risk.
  • PTLD (Post-Transplant Lymphoproliferative Disorder):
    • EBV-driven lymphoma; risk ↑ with immunosuppression intensity.
    • Sx: Fever, lymphadenopathy.
    • Rx: Reduce immunosuppression, Rituximab.

    ⭐ PTLD is most commonly associated with Epstein-Barr Virus (EBV) infection in transplant recipients.

GVHD & Other Complications - Graft's Grudge

  • Graft-versus-Host Disease (GVHD): Donor T-cells attack recipient tissues. 📌 Targets: Skin, Liver, Gut.
    • Acute GVHD: Develops <100 days. Affects skin (maculopapular rash), liver (↑bilirubin, ↑LFTs), GIT (diarrhea, pain).
    • Chronic GVHD: Develops >100 days. Autoimmune-like; multi-organ (skin, mouth, eyes, joints, lungs).
    • Prophylaxis/Treatment: Immunosuppressants (CNIs, methotrexate), steroids.
  • Surgical Complications:
    • Vascular: Arterial/venous thrombosis, stenosis.
    • Organ-specific: Biliary strictures/leaks (liver); lymphocele, urinoma (kidney).
    • General: Wound infection, dehiscence.
  • Long-term Sequelae:
    • Malignancy: PTLD (EBV-associated), skin cancers (SCC > BCC), Kaposi sarcoma.
    • Cardiovascular disease (accelerated).
    • Nephrotoxicity (CNIs).
    • Opportunistic infections. GVHD skin rash and PTLD lymph node biopsy

⭐ Post-Transplant Lymphoproliferative Disorder (PTLD) is a significant EBV-related malignancy risk, especially in the first year.

High‑Yield Points - ⚡ Biggest Takeaways

  • Hyperacute rejection is antibody-mediated (Type II hypersensitivity), occurring minutes to hours post-transplant.
  • Acute rejection, typically T-cell mediated (Type IV), occurs days to weeks later; it's the most common type.
  • Chronic rejection involves fibrosis and scarring, leading to graft loss over months to years.
  • Opportunistic infections like CMV, PJP, and BK virus are significant post-transplant risks.
  • Increased risk of malignancies, especially PTLD (EBV-related) and skin cancers.
  • Calcineurin inhibitor toxicity (e.g., nephrotoxicity, neurotoxicity) is a major long-term concern.
  • Graft-versus-host disease (GVHD) is a critical complication, especially in bone marrow transplants but can occur in solid organs too.

Practice Questions: Complications of Transplantation

Test your understanding with these related questions

A man has undergone renal transplant and is taking immunosuppressant drug. On biopsy there was presence of budding cells with pseudohyphae. Identify the organism?

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Flashcards: Complications of Transplantation

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Organ implanted in different anatomic location in the recipient as it was in the donor is known as _____ transplantation

TAP TO REVEAL ANSWER

Organ implanted in different anatomic location in the recipient as it was in the donor is known as _____ transplantation

heterotopic

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