How Do You Manage To Decrease Anti A And B Titers
The management of anti-A and anti-B antibody titers in ABO-incompatible (ABOi) kidney transplantation is achieved through a three-pronged desensitization strategy: physical removal of circulating antibodies, pharmacological inhibition of antibody production, and general immunosuppression to dampen the immune response.
- Physical Removal of Circulating Antibodies
The goal is to reduce titers to a “safe” level (typically <1:8) before surgery to prevent hyper-acute rejection.
- Antigen-Specific Immunoadsorption (IA):
The modern cornerstone of many European protocols. It uses a specific adsorption column (e.g., Glycosorb) coated with synthetic A or B antigens to selectively clear antibodies from the plasma without removing essential components such as coagulation factors or protective immunoglobulins. - Plasmapheresis (PE/PEX):
A less expensive, widely available method in which the recipient’s plasma is removed and replaced with albumin or fresh frozen plasma. - Double-Filtration Plasmapheresis (DFPP):
A variation that selectively removes the gamma-globulin fraction of the plasma, allowing for the elimination of large amounts of immunoglobulins in a single session.
- Inhibition of Antibody Production
Because physical removal is temporary, the body’s ability to produce new anti-ABO antibodies must be suppressed.
- Rituximab:
The “game-changer” in ABOi transplantation. This anti-CD20 monoclonal antibody depletes the circulating B-cell population and has largely replaced splenectomy, which was historically used to reduce antibody production. - Splenectomy:
Now considered obsolete. Previously performed to prevent antibody rebound.
- Specialized Strategies
- “On-Demand” Postoperative Care:
Early protocols used routine postoperative antibody removal (e.g., on days 1, 4, and 7). Many centers now withhold postoperative IA unless a significant “rebound” in titers occurs (e.g., >1:16 or >1:32).
A2 Subgroup Donors:
If the donor is from the A2 subgroup (a low-antigen expresser) and the recipient has low baseline titers (≤1:8–1:16), transplantation may be performed without any antibody removal or desensitization.
