Can an O (O positive) blood group donor donate a liver to an A (A positive) blood group recipient?

ABO-Incompatible Liver Transplantation: O Positive to A Positive

Yes, an O positive donor can donate a liver to an A positive recipient, but this represents an ABO-incompatible transplant that requires specialized protocols and carries increased risks compared to ABO-compatible transplantation.

Understanding the Blood Group Mismatch

This scenario involves transplanting from a universal donor (O) to a non-O recipient (A), which is the opposite direction of the more commonly discussed A2-to-O transplants. The O-to-A combination means:

• The O donor liver lacks A antigens
• The A positive recipient has naturally occurring anti-B antibodies (but not anti-A antibodies)
• This is actually a favorable ABO-incompatible scenario because the recipient lacks antibodies against the donor's blood type

Clinical Feasibility and Outcomes

While the provided guidelines focus primarily on donor selection criteria for viral infections, steatosis, and malignancy rather than ABO compatibility 1, the research evidence addresses ABO-incompatible transplantation:

• ABO-incompatible liver transplantation is feasible when proper immunomodulation protocols are implemented 2
• The liver has unique immunological properties that make it more tolerant of ABO incompatibility compared to other solid organs 3

Key Considerations for O-to-A Transplantation

Immunological Risk Assessment

• The O-to-A direction is less problematic than A-to-O because the A recipient does not have preformed anti-A antibodies that would attack an O liver 3
• However, passenger lymphocytes in the donor liver can produce anti-A antibodies that may affect the recipient 2

Required Protocols

Immunosuppression strategy:

• Induction therapy with antithymocyte globulin, IL-2 receptor antagonists, or anti-CD20 antibody (rituximab) 2
• Tacrolimus-based maintenance immunosuppression 2
• Consider triple immunosuppressive therapy given the potential for late rejection 3

Monitoring requirements:

• Serial anti-A isoagglutinin titer monitoring post-transplant 4, 2
• Baseline liver biopsies before or immediately after reperfusion 2
• Clinical biopsies when indicated 2

Potential Complications

Rejection patterns:

• Higher rates of acute cellular rejection have been reported in ABO-incompatible transplants 3
• Significant proportion of rejections may be late (>90 days post-transplant) or steroid-resistant 3
• Antibody-mediated rejection is possible, though less common in the O-to-A direction 4

Vascular complications:

• Portal vein thrombosis has been reported, potentially related to antibody-mediated injury 2
• No hyperacute rejection expected in properly managed cases 2

Clinical Outcomes

Research demonstrates that ABO-incompatible liver transplantation can achieve:

• Patient survival of 83% in mixed ABO-incompatible cohorts 2
• Graft survival of 67-80% depending on specific blood group combinations 2, 3
• All six patients in one series of A2-to-O transplants (the reverse of your scenario) had functioning grafts with mean follow-up of 665 days 3

Critical Caveats

Important distinctions:

• The O-to-A scenario you describe is less risky than A-to-O because the recipient lacks antibodies against the donor antigens 3
• Most published data focuses on A2-to-O transplants; direct O-to-A data is limited but the immunological principles are favorable 2, 3
• Plasmapheresis may not be necessary in the O-to-A direction, unlike some other ABO-incompatible combinations 3

When to consider this option:

• Urgent clinical situations where ABO-compatible grafts are unavailable 2
• Patients with rapid deterioration of liver function 2
• After careful risk-benefit assessment and informed consent 2

Practical Algorithm

1. Confirm blood types and ensure O donor to A recipient matching
2. Assess recipient urgency and availability of ABO-compatible alternatives
3. Obtain informed consent regarding increased rejection risk
4. Implement induction immunosuppression at time of transplant 2
5. Perform baseline biopsy at reperfusion 2
6. Monitor anti-A titers serially post-transplant 4, 2
7. Maintain heightened vigilance for late rejection episodes beyond 90 days 3
8. Consider triple immunosuppression rather than dual therapy 3