Decreased Risks and Better Success for Low-Titer ABO-Incompatible Recipients
Recipients of ABO-incompatible (ABOi) kidney transplants with low anti-A/B antibody titers (typically defined as baseline titers ≤1:64 or pre-operative titers ≤1:8) experience a significantly safer clinical course and superior survival outcomes compared to high-titer recipients.
The decreased risk for these patients is attributed to a lower burden of desensitization, reduced immunological reactions, and fewer secondary complications.
- Survival and Mortality Benefits
Low-titer recipients achieve a clear survival advantage that is often not observed in high-titer groups:
- Waitlist vs. Transplant: In large cohorts, low-titer recipients (≤1:64) show significantly better patient survival rates than those remaining on deceased donor waitlists.
- High-Titer Attenuation: Conversely, high-titer groups (≥1:128) may show no significant survival benefit over remaining on the waitlist. This is because the high infectious burden required to treat high antibody levels can negate the survival advantages of the transplant.
- Long-Term Graft Stability: Recipients with low IgG titers (≤1:8) have a significantly lower risk of graft failure compared to high-titer recipients.
- Reduced Bleeding and Surgical Risk
The most critical predictor of post-operative bleeding is the intensity of pre-operative filtration:
- Session Predictability: The number of pre-operative immunoadsorption (IA) or plasmapheresis sessions is the only independent predictor of the need for blood transfusions.
- Platelet Preservation: Low-titer patients reach the required safety threshold (usually <1:8) with fewer sessions. Consequently, they avoid the cumulative mechanical stress on platelets that causes “oozing” and major bleeding during and after surgery.
- Lower Infectious Burden
Aggressive desensitization for high titers increases the total immunosuppressive weight, whereas low-titer protocols are more conservative:
- Bacterial Infection: Patients in high-titer groups are significantly more likely to experience bacterial infections — roughly 23% compared to 14.3% in low-titer groups.
- Selective Treatment: Because low-titer patients require less intensive B-cell depletion and antibody removal, their natural immune defenses (protective immunoglobulins) are better preserved.
- Feasibility of Simplified Protocols
For some low-titer combinations, the procedure is so safe that standard desensitization can be reduced or omitted:
- Omitting Antibody Removal: Favorable results have been achieved in both pediatric and adult populations without any pre-operative antibody removal if baseline IgG titers are ≤1:64.
- A2 to B Transplants: In living donor A2/A2B → B transplants, it is feasible to proceed without desensitization if IgG titers are ≤1:8 or ≤1:16.
Withholding Post-Op IA: If pre-operative titers are strictly held to <1:8, routine post-operative antibody removal can be safely withheld, as there is no observed association between low post-operative titers and rejection.
