Baseline Anti-blood Group Antibody Titers and their Response to Desensitization and Kidney Transplantation

In recent years, immunological barriers historically considered as absolute contraindications to transplantation are being reevaluated. One such barrier is the ABO blood group incompatibility. With better understanding of immunological mechanisms and effective various regimens for controlling it, ABO-incompatible (ABO-I) kidney transplantation is now being performed with increasing frequency. For good outcome, most important is to achieve and maintain low anti-blood group antibody titers (ABGATs). Twenty-two patients with ABO-I donors have been studied. The anti-A and anti-B antibody titers (IgG and IgM) were estimated by column agglutination technology using Automated Ortho BioVue System. For desensitization, pretransplant plasmapheresis and/or immunoadsorption and rituximab were used. ABGAT was determined before transplant and periodically after transplant. It was observed that one-third of the patients have low baseline ABGAT. In these cases with low ABGAT, transplant can be performed without any desensitization. In those with titers <1:256, rituximab (two doses of 200 mg weekly) and 3-6 sessions of plasmapheresis can bring down titers to <1:32. In those with titers >1:256, immunoadsorption may be used from the beginning to reduce ABGAT. After transplant, the titers drop to <1:8 in majority. Rise in titers to >1:64 require close observation and biopsy. If there is evidence of antibody-mediated rejection, treatment should be promptly started. Rise in titers 4-6 weeks after transplant is not associated with any graft dysfunction, and hence not of any clinical significance.