Regulatory Dendritic Cell Infusion Prolongs Kidney Allograft Survival in Nonhuman Primates

We examined the influence of regulatory dendritic cells (DCreg), generated from cytokine-mobilized donor blood monocytes in vitamin D3 and IL-10, on renal allograft survival in a clinically relevant rhesus macaque model. DCreg expressed low MHC class II and costimulatory molecules, but comparatively high levels of programmed death ligand-1 (B7-H1), and were resistant to pro-inflammatory cytokine-induced maturation. They were infused intravenously (3.5–10 × 10⁶/kg), together with the B7-CD28 costimulation blocking agent CTLA4Ig, 7 days before renal transplantation. CTLA4Ig was given for up to 8 weeks and rapamycin, started on Day −2, was maintained with tapering of blood levels until full withdrawal at 6 months. Median graft survival time was 39.5 days in control monkeys (no DC infusion; n = 6) and 113.5 days (p < 0.05) in DCreg-treated animals (n = 6). No adverse events were associated with DCreg infusion, and there was no evidence of induction of host sensitization based on circulating donor-specific alloantibody levels. Immunologic monitoring also revealed regulation of donor-reactive memory CD95⁺ T cells and reduced memory/regulatory T cell ratios in DCreg-treated monkeys compared with controls. Termination allograft histology showed moderate combined T cell- and Ab-mediated rejection in both groups. These findings justify further preclinical evaluation of DCreg therapy and their therapeutic potential in organ transplantation (read more)

Cryptic B Cell Response to Renal Transplantation

Transplantation reliably evokes allo-specific B cell and T cell responses in mice. Yet, human recipients of kidney transplants with normal function usually exhibit little or no antibody specific for the transplant donor during the early weeks and months after transplantation. Indeed, the absence of antidonor antibodies is taken to reflect effective immunosuppressive therapy and to predict a favorable outcome. Whether the absence of donor-specific antibodies reflects absence of a B cell response to the donor, tolerance to the donor or immunity masked by binding of donor-specific antibodies to the graft is not known. To distinguish between these possibilities, we devised a novel ELISPOT, using cultured donor, recipient and third-party fibroblasts as targets. We enumerated donor-specific antibody-secreting cells in the blood of nine renal allograft recipients with normal kidney function before and after transplantation. Although none of the nine subjects had detectable donor-specific antibodies before or after transplantation, all exhibited increases in the frequency of donor-specific antibody-secreting cells eight weeks after transplantation. The responses were directed against the donor HLA-class I antigens. The increase in frequency of donor-specific antibody-secreting cells after renal transplantation indicates that B cells respond specifically to the transplant donor more often than previously thought (read more)

Diabetes-Free Survival in Patients Who Underwent Islet Autotransplantation After 50% to 60% Distal Partial Pancreatectomy for Benign Pancreatic Tumors

Background: Several retrospective studies with short-term follow-up have demonstrated a low rate of new-onset diabetes after distal pancreatectomy for benign pancreatic tumors. We sought to determine the long-term diabetes-free survival of patients who underwent islet autotransplantation (IAT) after distal pancreatectomy and to identify any associations between the isolation parameters of autologous islets and diabetes-free survival.
Methods: Among the 37 nondiabetic patients who underwent 50% to 60% partial pancreatectomy, 20 underwent IAT (IAT group; median follow-up period, 61 months). In the IAT group, diabetes-free survival was determined based on annual oral glucose tolerance tests, fasting blood glucose, and hemoglobin A1C.
Results: The 7-year diabetes-free survival rate was 51% in the IAT group (median follow-up period, 61 months) and 45% in the 37 study subjects. Diabetes-free survival was significantly prolonged when islet yield per gram of pancreas weight was more than 5154 islet equivalents (IEQ)/g, even in patients with prediabetes and high insulin resistance who had a markedly high rate of diabetes development. The proportion of patients with impaired glucose tolerance at 2 years after distal pancreatectomy was 12 of 16 in the control group, 6 of 7 in patients with islet yields of less than 5154 IEQ/g, and 3 of 11 in patients with islet yields of more than 5154 IEQ/g (P=0.019).
Conclusions: Partial (50%–60%) pancreatectomy for benign pancreatic tumors had a major metabolic consequence, especially in patients with prediabetes and high insulin resistance. In this setting, prolonged diabetes-free survival was observed in patients who underwent IAT when a high islet yield per gram of pancreas was achieved (read more)

Beneficial Effects of Pretransplantation Microchimerism on Rejection-Free Survival in HLA-Haploidentical Family Donor Renal Transplantation

Background: Fetal-maternal microchimerism (MC) can develop during pregnancy and may persist for decades. Pretransplantation fetal-maternal MC may be present between mother and child and between siblings; however, its effect on renal transplantation is not known. We investigated the effects of pretransplantation MC on allograft outcomes in human leukocyte antigen (HLA)–haploidentical family donor transplantation.
Methods: A total of 106 cases transplanted from 1996 to 2004 were retrospectively studied, with median follow-up of 96 months. The study and control groups included 63 and 43 cases of HLA-haploidentical and HLA-identical donor transplantations, respectively. MC against mismatched donor HLA-DRB1 allele was detected in the recipient’s peripheral blood using nested polymerase chain reaction–single-strand conformation polymorphism method. The allograft outcomes of HLA-haploidentical MC (+) and (–) subgroups were compared with those of HLA-identical group.
Results: Pretransplantation MC in the HLA-haploidentical recipients was detected in 22.2% (14 of 63). Compared with HLA-identical group, MC (–) subgroup showed significantly inferior allograft outcomes: higher acute rejection rate (11.6% vs. 42.9%; P=0.001), higher 5-year serum creatinine level (1.1 vs. 1.4 mg/dL; P=0.009), and lower 10-year rejection-free survival rate (83.7% vs. 54.5%; log-rank P=0.001). In contrast, MC (+) subgroup showed no significant differences from HLA-identical group in acute rejection rate (14.3%), 5-year serum creatinine level (1.1 mg/dL), and 10-year rejection-free survival rate (85.7%). Multivariate analysis revealed that pretransplantation MC is associated with a significantly lower risk of acute rejection (odds ratio=0.10; P=0.021).
Conclusion: Pretransplantation MC present in the recipient may have beneficial effects on rejection-free allograft survival in renal transplantation (read more)

Proteasome Inhibition Profoundly Affects Activated Human B Cells

Background: Proteasome inhibitors, although initially developed for the treatment of malignancies, have been found to affect normal plasma cells by efficaciously inducing apoptosis. One proteasome inhibitor, bortezomib, has been used in transplantation settings to deplete human leukocyte antigen antibody-producing plasma cells to reverse humoral allograft rejection.
Methods: To establish whether proteasome inhibitors are active on B cells, being plasma cell precursors, we examined a set of four proteasome inhibitors, including bortezomib, carfilzomib, ONX 0912, and ONX 0914, for their potential to impact the functionalities of activated B cells in vitro.
Results: All proteasome inhibitors dose-dependently abrogated IgM and IgG production by activated B cells, as well as their proliferation, with varying efficiencies. The bortezomib-induced decline in immunoglobulin production was mainly due to a decrease in the number of B cells capable of immunoglobulin secretion, caused by apoptosis.
Conclusions: The action of proteasome inhibitors is not confined to plasma cells but also has impact on activated naïve and memory B cells (read more)

CMV Infection in the Donor and Increased Kidney Graft Loss: Impact of Full HLA-I Mismatch and Posttransplantation CD8+ Cell Reduction

Despite a large body of literature, the impact of chronic cytomegalovirus (CMV) infection in donor on long-term graft survival remains unclear, and factors modulating the effect of CMV infection on graft survival are presently unknown. In this retrospective study of 1279 kidney transplant patients, we analyzed long-term graft survival and evolution of CD8⁺ cell population in donors and recipients by CMV serology and antigenemia status. A positive CMV serology in the donor was an independent risk factor for graft loss, especially among CMV-positive recipients (R⁺). Antigenemia was not a risk factor for graft loss and kidneys from CMV-positive donors remained associated with poor graft survival among antigenemia-free recipients. Detrimental impact of donor's CMV seropositivity on graft survival was restricted to patients with full HLA-I mismatch, suggesting a role of CD8⁺ cells. In R⁺ patients with positive CMV antigenemia during the first year, CD8⁺ cell count did not increase at 2 years posttransplantation, in contrast to R⁻ recipients. In addition, marked CD8⁺-cell decrease was a risk factor of graft failure in these patients. This study identifies HLA-I full mismatch and a decrease of CD8⁺ cell count at 2 years as important determinants of CMV-associated graft loss (read more)

Prediction of kidney graft failure using clinical scoring tools

Background : Donor organ quality is a key determinant of graft function, and considerable efforts have been made to identify donor and transplant factors predicting inferior outcomes. This has resulted in the development of various scoring tools to aid in allocation of kidneys.
Methods : The performance of four donor quality scoring systems in predicting delayed graft function, and death-censored graft failure was examined in a single-center cohort of 730 consecutive deceased donor kidneys transplanted between 1990 and 2004. The predictive accuracy of the variables was analyzed with receiver operating characteristic curves and graft survival distribution.
Results : The three outcome tools, that is, deceased donor score (DDS; Am J Transplant, 3, 2003, 715), donor risk score (DRS; Am J Transplant, 5, 2005, 757) and kidney donor risk index (KDRI; Transplantation, 88, 2009, 231) provided a significant and equivalent prediction of graft failure by using variables available at time of transplantation (p < 0.01). The risk of delayed graft function was predicted by the (DGF) nomogram (J Am Soc Nephrol, 14, 2003, 2967; Am J Transplant 10, 2010, 2279) with a high degree of discrimination (concordance index of 0.69, p < 0.01).
Conclusions : Our findings validate four pre-operative clinical scoring tools to predict early and late graft outcome in an independent, single-center set of kidney transplants (read more)