Post-transplant Desensitization for Deceased Donor Kidney Transplant Recipients: A Single Center Experience.

The highly-sensitized kidney transplant candidate with no available living donors remains at a major disadvantage with decreased access and worse outcomes post-transplant. We have previously reported our initial data on both pre-transplant and post-transplant desensitization. We observed only a modest decline in unacceptable antigens with pretransplant intravenous immunoglobin (IVIG) and rituximab. Due to these observations, we have focused on a peri-operative post-transplant desensitization protocol in our program. Beginning in 2006, we implemented a simple point-based algorithm [variables included: panel reactive antibody (PRA) status; flow cytometric crossmatch (FCXM); and delayed graft function] to identify kidney transplant recipients who would undergo peri-operative plasmapheresis/IVIG to abrogate preformed antibody-mediated allograft rejection (AMR). Our previous results suggested acceptable 5-year outcomes. Here, in an expanded population (N=66), we report an overall death-censored graft survival of 73% at a mean follow-up of 8.5 years post-transplant. Our patients were largely African American (85%) and regrafts (39%), with a median PRA of 88%, and a mean T- and B-FCXM of 97 mean channel shifts (MCS) and 117 MCS, respectively. Although acute AMR rates were acceptable (12%), 22% of patients developed chronic AMR. A pre-transplant T-cell FCXM of > 200 MCS (p=0.02) or presence of donor specific antibodies (DSA) at most recent follow-up (p=0.02) were associated with graft loss. Current studies with revised protocols utilizing additional DSA information, surveillance biopsies, and proteasome inhibition are ongoing.

Effects of Two Preemptive Post-transplant Desensitization Regimens Upon Renal Allograft Survival and DSA Elaboration.

We used a simple point-based algorithm to identify patients who might benefit from desensitization because of their higher risk of antibody-mediated chronic rejection and graft failure. Points were assigned to known but easily determined risk factors (panel reactive antibody, flow crossmatch, delayed graft function) and calculated immediately after deceased donor kidney transplantation. Point totals were used to identify: 1) which patients would receive desensitization; and, 2) which regimen each patient would receive. This standardized approached resulted in improved overall graft survival in both modalities compared to historically untreated sensitized patients. While preemptive desensitization positively impacted clinical metrics, the improvements were unequal between regimens. PP/IVIG treatment clearly resulted in greater elimination of preexisting donor specific antibodies against HLA antigens (DSA), fewer late rejections, and superior 3-year graft survival among patients who resolved their DSA as well as those with persistent DSA. Since graft survival among PP/IVIG recipients was excellent even when preexisting DSA were still present one year post-transplant, it suggests that the benefit of this regimen is two-fold: first to increase DSA elimination among patients, and secondly, to minimize downstream immune activating events such as rejection. In contrast, IVIG patients with persistent DSA had more rejections and graft survival only slightly better than if they had no treatment at all. Since the IVIG group also had a preponderance of Class II directed DSA, we cannot discount the influence of that specificity upon graft outcomes. Additional studies are needed to confirm our findings and to allow more effective assessment of the impact of DSA specificity upon desensitization efficacy and graft success.