Clinical Experience with a New Apheresis Filter That Specifically Depletes ABO Blood Group Antibodies.

Background:

The shortage of organs for transplantation is a well-known problem and one of the means to increase the donor pool is the use of ABO blood group incompatible donors. Presently, in most transplant centers, between 30% and 40% of potential donors are turned down due to ABO blood group incompatibility. Recently a low-molecular carbohydrate column with A or B blood group antigen linked to a sepharose matrix (Glucosorb-ABO, Glycorex Transplantation, Lund, Sweden) that specifically depletes anti-A or anti-B antibodies was registered in Europe and we have had the opportunity to evaluate this device in eleven patients who successfully have received ABO incompatible renal grafts, four of which have been reported earlier (

Method:

Pretransplant conditioning was started on day −10 with one infusion of rituximab 375 mg/m^2, followed by tacrolimus 0,3 mg/kg, mycophenolate mofetil 3g and prednisolone 30 mg. On day −1 0,5 mg/kg of intravenous immunoglobulin was administered. Patient plasma (1–2 plasma volumes per session) was recirculated through the column using CobeSpectra apheresis machine. Anti-A and anti-B titers were analysed using standard direct (NaCl) and indirect (IAT) agglutination techniques. In the adult or adolescent patients immunoglobulins, including IgG-subclass antibodies and specific antibodies against protein and carbohydrate antigens, were analysed before first apheresis and after last apheresis before renal transplant.

Results:

ABO blood group antibody titers were lowered up to fours steps per apheresis procedure. No side effects were detected. So far eleven patients including two infants have been successfully transplanted with ABO-incompatible living donors using this protocol. Donor blood groups were: four A1, one A1B, four B and two A2. See Table1 for patient data. IgG, IgG1 and IgM were lowered to slightly subnormal levels pre transplant while IgA, IgG2, IgG3 and IgG4 remained normal. Levels of specific antibodies against protein and carbohydrate antigens were not affected. Since ABO antibodies are of IgG and IgM immunoglobulin class, the decrease is quite logical and the fact that levels of specific antibodies were unchanged confirms the specificity of the column.

Conclusion:

Our experience shows that ABO-blood group antibodies can be effectively and specifically depleted without any side-effects using the Glucosorb-ABO column and that antibody production can be effectively suppressed without splenectomy. Specific depletion of ABO blood group antibodies is a new apheresis method with significant advantages for patients compared to multiple sessions of plasmapheresis since the patients own plasma is recirculated through the column and no donor plasma or other substitution fluids are needed.

Table 1 Patient data