Do ABO (A and B antigens present on red blood cells) blood type antigens play a role in determining donor eligibility for kidney transplantation?

ABO Blood Type Antigens Are Critical for Kidney Donor Eligibility

ABO blood group compatibility is essential for kidney transplantation as antibodies to major blood group antigens can cause hyperacute rejection and graft failure. 1 The standard practice requires that the blood group of the recipient should be compatible with that of the donor to ensure optimal transplant outcomes.

ABO Compatibility Requirements

• ABO blood typing should be performed twice before donation to reduce the risk of unintended blood type incompatible transplantation 1
• Donor blood group A subtype testing should be performed when donation is planned for recipients with anti-A antibodies 1
• The A2 blood type has lower blood group antigen expression, behaves like an O blood type, and may be successfully transplanted into O recipients in certain circumstances 1

Histocompatibility Testing Framework

Histocompatibility testing for kidney transplantation relies on three key principles:

1. ABO blood group compatibility - The primary consideration for donor eligibility 1
2. HLA matching - Matching for human leukocyte antigens improves long-term outcomes 1
3. Donor-specific crossmatching - Excludes donor organs from recipients with preexisting anti-donor immunity 1

ABO-Incompatible Transplantation

While ABO compatibility is the standard approach, ABO-incompatible transplantation has become more feasible with specific desensitization protocols:

• Desensitization strategies include transient removal of preformed anti-A or anti-B antibodies using plasmapheresis or immunoadsorption 2
• B-cell immunity modulation with rituximab (anti-CD20) combined with maintenance immunosuppression is typically required 2
• ABO-incompatible transplantation carries increased risks of bleeding and infectious complications 2
• Despite advances, ABO-incompatible transplantation should still be considered experimental according to clinical practice guidelines 1

Minor Blood Group Antigens

• Beyond ABO, at least 35 minor blood group antigens exist with immunogenic potential 3
• Evidence shows renal expression of antigens from the Kidd, MNS, Duffy, and Lewis groups, which could potentially cross-react in a transplanted kidney 3
• Anti-A antibodies can sometimes cause false-positive T and B-cell crossmatch results, complicating transplant evaluation 4

Clinical Approach to Blood Type Compatibility

1. Determine ABO blood type compatibility between donor and recipient 1
2. If compatible, proceed with standard transplant evaluation
3. If incompatible, consider:
   • Kidney paired donation programs 1
   • Desensitization protocols at experienced centers 2
   • A2 to O transplantation when appropriate 1

Practical Considerations

• ABO compatibility testing is the first step in donor evaluation before proceeding to more complex histocompatibility testing 1
• After ABO compatibility, the pretransplant crossmatch represents the most important procedure performed in the histocompatibility laboratory 1
• Recipients should be informed about the risks and benefits of different transplant options based on blood type compatibility 1

Pitfalls and Caveats

• Relying solely on ABO compatibility without proper crossmatching can lead to transplant failure 1
• Anti-A antibodies can sometimes bind to type A substances on donor lymphocytes, causing false-positive crossmatch results 4
• Different antibody detection methods between laboratories can lead to variations in antibody titer results, affecting transplant decisions 5
• ABO-incompatible transplantation should only be performed at centers with experience in effective incompatibility management strategies 1