What is PRA?
PRA stands for Panel Reactive Antibodies. It is a blood test used to measure a patient’s level of sensitization to human leukocyte antigens (HLA). These antigens are proteins found on most cells in the body. If the patient has antibodies against these antigens, it can lead to rejection of a transplanted organ.
The PRA test gives a percentage that reflects the proportion of the general population the patient’s immune system may react against. For example:
- PRA < 4% – Negative
- PRA 4-10% – Weak Positive
- PRA 11-50% – Moderate Positive
- PRA > 50% – Strong Positive
Why is PRA Important?
A high PRA means the patient’s immune system is more likely to attack a donor kidney, leading to rejection. These patients have a harder time finding a compatible donor and require special management before transplantation.
Causes of High PRA
Patients may develop high PRA due to exposure to foreign HLA antigens from:
- Previous organ transplants
- Multiple blood transfusions
- Pregnancies
- Infections or immune reactions
Who Needs PRA Testing?
PRA testing is essential for:
- All kidney transplant candidates
- Patients awaiting second or third transplant
- Women with multiple pregnancies
- Patients with a history of blood transfusions
What If PRA is Positive?
High PRA is not the end of the road. There are treatments available to lower the antibody levels and reduce the risk of rejection. These include:
1. DSA Testing
If a specific donor is chosen, a Donor-Specific Antibody (DSA) test checks for antibodies against that donor’s HLA antigens.
2. Desensitization Therapy
This process reduces antibody levels before the transplant:
- Plasmapheresis: Removes antibodies from the bloodstream
- IVIG (Intravenous Immunoglobulin): Suppresses the immune response
- Medications: Rituximab, Bortezomib, or Eculizumab
3. Post-Transplant Immunosuppression
Patients with high PRA may need stronger or tailored immunosuppressive regimens, including Tacrolimus, Mycophenolate Mofetil, ATG, or Basiliximab.
Role of PRA in Donor Matching
PRA is used to assess the risk of rejection and to guide donor selection. In deceased donor transplantation, high PRA patients are prioritized under special matching protocols. In living donor cases, DSA-negative status and pre-transplant desensitization improve outcomes.
Summary
| Aspect | Details |
|---|---|
| What is PRA? | A test measuring sensitization to HLA antigens |
| Why is it important? | Indicates risk of rejection and compatibility issues |
| Who needs it? | All kidney transplant candidates, especially those sensitized |
| Treatment if positive | Desensitization, DSA testing, enhanced immunosuppression |
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