Removal of preformed cytotoxic antibody using PROSORBA (Staph Protein-A-Silica) column without immunosuppression

Antibody-mediated rejection: treatment alternatives and outcomes

Over the past 10 years, thanks to the development of sensitive methods of antibody detection and markers of antibody injury such as C4d staining, the role of anti-human leukocyte antigen (HLA) and non-HLA alloantibodies as effectors of acute and chronic immune allograft injury has been revisited. Antibody-mediated rejection (AMR) defines all allograft rejection caused by antibodies directed against donor-specific HLA molecules, blood group antigen (ABO)-isoagglutinins, or endothelial cell antigens. Antibody-mediated rejection can be a recalcitrant process, resistant to therapy and carries an ominous prognosis to the graft. In concordance with these views, treatment protocols for AMR use permutations of a multiple-prong approach that include (1) the suppression of the T-cell dependent antibody response, (2) the removal of donor reactive antibody, (3) the blockade of the residual alloantibody, and (4) the depletion of naive and memory B-cells. Although all published protocols report a variable rate of success, a major weakness of all current protocols is the lack of effective anti-plasma cell agents. In comparison to acute AMR, the treatment for chronic AMR (CAMR) is not well characterized. Although in acute AMR large titers of pre-existent alloantibodies result in massive activation of the complement system and lytic injury of the graft endothelium, thereby requiring aggressive and fast removal of the offending agents, in CAMR, complement activation results in sublytic endothelial cell injury and activation. Although this type of injury results in chronic graft failure, its slow progression likely renders it amenable of suppression by heightening of maintenance immunosuppression and anti-idiotypic blockade of the circulating alloantibody without the need of plasma exchange. In this review, we will discuss the rationale behind the design of treatment protocols for acute AMR and CAMR as well as their reported results and complications.

Successful renal transplant outcome after intravenous gamma-globulin treatment of a highly sensitized pediatric recipient

Approximately 10% of patients on the renal transplant (Tx) cadaver waiting list have high (> 20%) panel-reactive antibody (PRA) levels to human leukocyte antigens (HLA). Intravenous gamma-globulin (IVIG) has been shown to reduce anti-HLA cytotoxic antibody levels through an anti-idiotypic antibody-blocking effect. We report a successful renal Tx outcome in a 7-yr-old-girl with high PRA levels owing to a failed renal Tx who experienced a significant reduction in PRA levels (from 96% to 0%) concomitant with IVIG therapy. IVIG was infused weekly (500 mg/kg/week) for 3 consecutive weeks every 12 weeks. Thirty-four months after starting IVIG therapy, the PRA activity dropped to zero and IVIG was stopped. Then IVIG therapy was resumed after 8 months due to a rebound in PRA activity to 52%. Forty-four months after starting IVIG therapy, the patient was cross-matched with a cadaver donor who shared three antigens with the first living donor. The cross-match was positive with the recipient's sera obtained prior to IVIG therapy and negative with the recipient's sera obtained post-IVIG therapy. A successful cadaver renal Tx was performed using anti-thymocyte globulin (ATGAM) induction therapy and a tacrolimus-based immunosuppression protocol. IVIG was given (1 g/kg) prior to Tx and at day 4 post-operatively. A single mild acute rejection episode occurred 10 days post-transplantation that responded to pulse methylprednisolone therapy and an increase in the tacrolimus oral dose. We conclude that a prolonged course of IVIG infusions, without immunosuppressive medications or plasmapheresis, is likely to have been beneficial in modulating the immune response in this highly sensitized recipient. Randomized multicenter trials are required to define the role of IVIG in this specific population.