ABO-incompatible kidney transplantation with anti-CD20 monoclonal antibodies, intravenous immunoglobulin and plasmapheresis without splenectomy: a case report

ABO blood group incompatibility: a diminishing barrier to successful kidney transplantation?

Blood type-incompatible transplantation has gained wide acceptance over the last decade. This is largely the result of B-cell-directed therapies aimed at modulating anti-blood group antibodies, which were the cause of the poor outcomes originally seen. Now rituximab (anti-CD20 and anti-B cell) has largely replaced splenectomy in preconditioning protocols, allowing for the wider implementation of ABO-incompatible transplants. Plasma exchange followed by intravenous immunoglobulin is also critical for the success of ABO-incompatible transplants. In this article, we describe the important contributions immunomodulatory drugs and antibody reduction therapies have made in achieving excellent outcomes in what was once an impenetrable barrier to transplantation.

Anti-CD20 antibody suppresses anti-HLA antibody formation in a HLA-A2 transgenic mouse model of sensitization

BACKGROUND

B cell depletion by anti-CD20 antibody is used in desensitization protocols and for treatment of antibody-mediated rejection (AMR). However, little is known about the efficacy and the mechanism(s) of action.

METHODS

A mouse model of HLA sensitization was used to study the effectiveness of anti-CD20 treatment on B cell depletion and anti-HLA antibody suppression.

RESULTS

Immunization of C57BL/6 mice with skin grafts from a transgenic C57BL.Tg/HLA-A2.1 mouse resulted in robust production of anti-HLA IgM and IgG antibodies, and accelerated rejection of a secondary skin allograft (within 3 days) featured by intragraft IgG and C4d deposition. Both IgM and IgG alloantibodies are specific to HLA-A2 as well as to a panel of class I HLA, including A1, A3, A25, A26, A29, and A30. These alloantibodies were complement-dependently cytotoxic (CDC) against HLA-A2 expressing target cells. Administration of 2 doses of a mouse-anti-mouse CD20 monoclonal antibody significantly reduced the levels of anti-HLA IgG2a antibodies, suppressed serum CDC, and prolonged survival of the secondary skin allografts. Suppression of anti-HLA IgG antibodies was associated with significant depletion of B220(+)/CD5(-) B cells from the blood, the spleen and the bone marrow of the treated animals.

CONCLUSION

Anti-CD20 treatment effectively depletes B220(+)/CD5(-) B cells, resulting in potent suppression of anti-HLA IgG and prolongation of skin graft survival. The data are in support for the use of anti-CD20 antibodies in highly-HLA sensitized patients undergoing desensitization and for the treatment of AMR.