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Characterization of anti-HLA versus anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) immune globulin isotypes in organ transplant recipients after coronavirus disease 2019 (COVID-19) infection has not been reported. We aimed to determine changes in anti-HLA antibodies in renal transplant patients with COVID-19 and compare the immunoglobulin and epitope-binding pattern versus anti-SARS-CoV-2 antibodies.This is a cross-sectional study of 46 kidney transplant recipients including 21 with longitudinal sampling. Using a semi-quantitative multiplex assay, we determined immunoglobulin (Ig) M, IgA, IgG, and IgG1-2-3-4 antibodies against Class I and Class II HLA, and 5 SARS-CoV-2 epitopes including the nucleocapsid protein and multiple regions of the spike protein.Fourteen of 46 (30%) patients had donor-specific anti-HLA antibodies (donor-specific antibody [DSA]), 12 (26%) had non-DSA anti-HLA antibodies and 45 (98%) had anti-SARS-CoV-2 antibodies. Most DSAs targeted HLA-DQ (71%), with a dominant IgG isotype and IgG1 subtype prevalence (93%), and/or IgG3 (64%), followed by IgG2 (36%). Comparatively, there was a higher prevalence of IgA (85% versus 14%, P = 0.0001) and IgM (87%, versus 36%, P = 0.001) in the anti-SARS-CoV-2 antibody profile, when compared to DSAs, respectively. Anti-SARS-CoV-2 antibody profile was characterized by increased prevalence of IgM and IgA, when compared to DSAs. The median calculated panel reactive antibody before COVID-19 diagnosis (24%) tended to decrease after COVID-19 diagnosis (10%) but it was not statistically significant ( P = 0.1).Anti-HLA antibody strength and calculated panel reactive antibody in kidney transplant recipients after COVID-19 do not significantly increase after infection. Although the IgG isotype was the dominant form in both HLA and SARS-CoV-2 antigens, the alloimmune response had a low IgA pattern, whereas anti-SARS-CoV-2 antibodies were high IgA/IgM.

Significant racial disparity remains in the incidence of unfavorable outcomes following heart transplantation. We sought to determine which pediatric posttransplantation outcomes differ by race and whether these can be explained by recipient demographic, clinical, and genetic attributes. Data were collected for 80 black and 450 nonblack pediatric recipients transplanted at 1 of 6 centers between 1993 and 2008. Genotyping was performed for 20 candidate genes. Average follow-up was 6.25 years. Unadjusted 5-year rates for death (p = 0.001), graft loss (p = 0.015), acute rejection with severe hemodynamic compromise (p = 0.001), late rejection (p = 0.005), and late rejection with hemodynamic compromise (p = 0.004) were significantly higher among blacks compared with nonblacks. Black recipients were more likely to be older at the time of transplantation (p < 0.001), suffer from cardiomyopathy (p = 0.004), and have public insurance (p < 0.001), and were less likely to undergo induction therapy (p = 0.0039). In multivariate regression models adjusting for age, sex, cardiac diagnosis, insurance status, and genetic variations, black race remained a significant risk factor for all the above outcomes. These clinical and genetic variables explained only 8-19% of the excess risk observed for black recipients. We have confirmed racial differences in survival, graft loss, and several rejection outcomes following heart transplantation in children, which could not be fully explained by differences in recipient attributes.

Reduction in donor-specific antibody (DSA) has been associated with improved renal allograft survival after antibody-mediated rejection (AMR). These observations have not been separately analyzed for early and late AMR and mixed acute rejection (MAR). The purpose of this study was to evaluate long-term responses to proteasome inhibitor-based therapy for 4 rejection phenotypes and to determine factors that predict allograft survival.Retrospective cohort study evaluating renal transplant recipients with first AMR episodes treated with proteasome inhibitor-based therapy from January 2005 to July 2015.A total of 108 patients were included in the analysis. Immunodominant DSA reduction at 14 days differed significantly (early AMR 79.6%, early MAR 54.7%, late AMR 23.4%, late MAR 21.1%, P0.001). Death-censored graft survival (DCGS) differed at 3 years postrejection (early AMR 88.3% versus early MAR 77.8% versus late AMR 56.7% versus late MAR 54.9%, P = 0.02). Multivariate analysis revealed that immunodominant DSA reduction50% at 14 days was associated with improved DCGS (odds ratio, 0.12, 95% CI, 0.02-0.52, P = 0.01).In summary, significant differences exist across rejection phenotypes with respect to histological and DSA responses. The data suggest that DSA reduction may be associated with improved DCGS in both early and late AMR.

Proteasome inhibitor-based strategies hold promise in transplant but have yielded varying results. Carfilzomib, a second-generation proteasome inhibitor, may possess advantages over bortezomib, the first-generation proteasome inhibitors. The purpose of this study was to evaluate the safety, toxicity, and preliminary efficacy of carfilzomib in highly HLA-sensitized kidney transplant candidates. Renal transplant candidates received escalating doses of carfilzomib followed by plasmapheresis (group A) or an identical regimen with additional plasmapheresis once weekly before carfilzomib dosing. Thirteen participants received carfilzomib, which was well tolerated with most adverse events classified as low grade. The safety profile was similar to bortezomib desensitization; however, neurotoxicity was not observed with carfilzomib. Toxicity resulted in permanent dose reduction in 1 participant but caused no withdrawals or deaths. HLA antibodies were substantially reduced with carfilzomib alone, and median maximal immunodominant antibody reduction was 72.8% (69.8% for group A, P = .031, 80.1% for group B, P = .938). After depletion, rebound occurred rapidly and antibody levels returned to baseline between days 81 and 141. Bone marrow studies revealed that approximately 69.2% of plasma cells were depleted after carfilzomib monotherapy. Carfilzomib monotherapy-based desensitization provides an acceptable safety and toxicity profile while leading to significant bone marrow plasma cell depletion and anti-HLA antibody reduction.

Donor-specific antibodies (DSAs) have a deleterious effect on allografts and remain a major immunologic barrier in transplantation. Current therapies to eliminate DSAs are ineffective in highly HLA-sensitized patients. Proteasome inhibitors have been employed as a strategy to target bone marrow plasma cells (BMPCs), the source of long-term antibody production; however, their efficacy has been limited by poorly defined drug-resistance mechanisms. Here, we performed transcriptomic profiling of CD138+ BMPCs that survived in vivo desensitization therapy with the proteasome inhibitor carfilzomib to identify mechanisms of drug resistance. The results revealed a genomic signature that included increased expression of the immunoproteasome, a highly specialized proteasomal variant. Western blotting and functional studies demonstrated that catalytically active immunoproteasomes and the immunoproteasome activator PA28 were upregulated in carfilzomib-resistant BMPCs. Carfilzomib-resistant BMPCs displayed reduced sensitivity to the proteasome inhibitors carfilzomib, bortezomib, and ixazomib, but enhanced sensitivity to an immunoproteasome-specific inhibitor ONX-0914. Finally, in vitro carfilzomib treatment of BMPCs from HLA-sensitized patients increased levels of the immunoproteasome β5i (PSMB8) catalytic subunit suggesting that carfilzomib therapy directly induces an adaptive immunoproteasome response. Taken together, our results indicate that carfilzomib induces structural changes in proteasomes and immunoproteasome formation.

Background Classification of acute rejection (AR) based on etiology and timing may provide a means for enhancing therapeutic results and allograft survival. This study evaluated graft and patient survival after the first AR episodes among kidney transplant recipients with an early or late antibody-mediated rejection (AMR), acute cellular rejection (ACR) or mixed AR (MAR). Methods A prospective institutional review board-approved database was queried to identify biopsy-proven first AR episodes occurring from January 2005 to October 2012. The ACR was defined by Banff criteria; borderline AR was excluded. The AMR was defined as 3 of 4 criteria: renal dysfunction, donor specific antibody, C4d positivity on biopsy, and histological changes. The MAR met criteria for both ACR and AMR. Early AR occurred within six months post-transplant. AR episodes were then assigned to 1 of the 6 categories--early AMR, early ACR, early MAR, late AMR, late ACR, and late MAR. Results One hundred eighty-two kidney transplant recipients identified with a first AR episode. Mean follow-up was 773 days (± 715 days). No difference was observed in patient survival. Death-censored graft survival was 84%. Death-censored graft loss was higher with late versus early AMR (P = 0.01) and late versus early ACR (P = 0.03), but not late versus early MAR (P = 0.3). Conclusions The AR type demonstrated a hierarchy for graft survival with ACR better than MAR better than AMR, which persisted for both early and late AR. Improvement in long-term results of AR may require development of specific treatment for individual AR types.

Background Highly sensitized patients, who produce antibodies against multiple anti-human leukocyte antigens, have significantly reduced chances for renal transplantation. Traditionally, desensitization protocols to reduce the levels of antibodies have relied on the use of intravenous immunoglobulin and plasmapheresis. Results Here we report the case of a patient with a calculated panel-reactive antibody level of 100% who was desensitized using multiple courses of bortezomib, a proteasome inhibitor, in an intravenous immunoglobulin-free regimen. The patient underwent a successful transplantation with an allograft from a living donor and has continued to do well post-transplantation. Conclusions The expression of anti-human leukocyte antigen antibodies decreases the likelihood of transplantation for patients by restricting the available donor pool. New protocols that reduce antibody expression in these patients and allow for renal transplantation are needed. Bortezomib, as used in the patient reported here, represents a promising new medication for successful desensitization and transplantation.

A prospective iterative trial of proteasome inhibitor (PI)-based therapy for reducing HLA antibody (Ab) levels was conducted in five phases differing in bortezomib dosing density and plasmapheresis timing. Phases included 1 or 2 bortezomib cycles (1.3 mg/m(2) × 6-8 doses), one rituximab dose and plasmapheresis. HLA Abs were measured by solid phase and flow cytometry (FCM) assays. Immunodominant Ab (iAb) was defined as highest HLA Ab level. Forty-four patients received 52 desensitization courses (7 patients enrolled in multiple phases): Phase 1 (n = 20), Phase 2 (n = 12), Phase 3 (n = 10), Phase 4 (n = 5), Phase 5 (n = 5). iAb reductions were observed in 38 of 44 (86%) patients and persisted up to 10 months. In Phase 1, a 51.5% iAb reduction was observed at 28 days with bortezomib alone. iAb reductions increased with higher bortezomib dosing densities and included class I, II, and public antigens (HLA DRβ3, HLA DRβ4 and HLA DRβ5). FCM median channel shifts decreased in 11/11 (100%) patients by a mean of 103 ± 54 mean channel shifts (log scale). Nineteen out of 44 patients (43.2%) were transplanted with low acute rejection rates (18.8%) and de novo DSA formation (12.5%). In conclusion, PI-based desensitization consistently and durably reduces HLA Ab levels providing an alternative to intravenous immune globulin-based desensitization.

The cyclolignan picropodophyllin (PPP) efficiently blocks the activity of insulinlike growth factor-1 receptor (IGF-1R) and inhibits the growth of uveal melanoma cells in vitro and in vivo. In this study, the authors investigated the efficiency of orally administered PPP on the growth of uveal melanoma xenografts. In addition, they focused on the effect of PPP on vascular endothelial growth factor (VEGF) in vivo and evaluated its effects in combination with other established antitumor agents in vitro.Four different uveal melanoma cell lines (OCM-1, OCM-3, OCM-8, 92-1) were treated with PPP alone and in combination with imatinib mesylate, cisplatin, 5-fluorouracil, and doxorubicin. Cell viability was determined by XTT assay. SCID mice that underwent xenografting with uveal melanoma cells were used to determine antitumor efficacy of oral PPP in vivo. Five mice were used per group. Tumor samples obtained from the in vivo experiments were analyzed for VEGF and IGF-1R expression by Western blotting.PPP was found to be superior to the other antitumor agents in killing uveal melanoma cells in all four cell lines (IC500.05 microM). Oral PPP inhibited uveal melanoma growth in vivo in OCM-3 (P = 0.03) and OCM-8 (P = 0.01) xenografts and was well tolerated by the animals. PPP decreased VEGF expression in the OCM-1 (P = 0.006) and OCM-8 (P = 0.01) tumors.Oral PPP was well tolerated in vivo, caused total growth inhibition of uveal melanoma xenografts, and decreased VEGF levels in the tumors.

OBJECTIVE: The objective of this study was to determine the association between the genetic polymorphisms of proinflammatory and regulatory cytokines and long-term rates of repeat and late acute rejection episodes in pediatric heart transplant (PHTx) recipients. METHODS: Three hundred twenty-three PHTx recipients: 205 White non-Hispanic, 43 Black non-Hispanic, and 75 Hispanic were analyzed for time to first repeat and late acute rejection episodes by race, age at transplantation, and gene polymorphism (interleukin [IL]-6, -174 G/C, IL-10, -1082 G/A, -819 C/T, 592 C/A; vascular endothelial growth factor (VEGF) -2578 C/A, -460 C/T, +405 C/G; tumor necrosis factor alpha (TNF-alpha)-308 G/A). RESULTS: Recipient black race and older age at transplant were risk factors for both repeat and late rejections, though black race was more significantly related to late rejection (P=0.006). Individually, TNF-alpha high, IL-6 high, VEGF high, and IL-10 low phenotypes did not impact the risk of repeat or late rejection. However, the combination VEGF high/IL-6 high and IL-10 low was associated with increased estimated risk of late rejection (P=0.0004) and only marginally with repeat rejection (P=0.051). In a multivariate analysis, adjusting for age and race, VEGF high/IL-6 high and IL-10 low still remained an independent risk factor for late acute rejection (RR=1.91, P

AMR is being recognized with increasing efficiency, but continues to present a significant threat to renal allograft survival. Traditional therapies for AMR (IVIG, plasmapheresis, rituximab, and antilymphocyte preparations) in general have provided inconsistent results and do not deplete the source of antibody production, viz., the mature plasma cell. Recently, the first plasma cell-targeted therapy in humans has been developed using bortezomib (a first in class PI) for AMR treatment in kidney transplant recipients. Initial experience with bortezomib involved treatment of refractory AMR. Subsequently, the efficacy of bortezomib in primary therapy for AMR was demonstrated. In a multicenter collaborative effort, the initial results with bortezomib in AMR have been confirmed and expanded to pediatric and adult heart transplant recipients. More recently, results from a prospective, staged desensitization trial has shown that bortezomib alone can substantially reduce anti-HLA antibody levels. These results demonstrate the significant potential of proteasome inhibition in addressing humoral barriers. However, the major advantage of proteasome inhibition lies in the numerous potential strategies for achieving synergy.

Purpose of review Bortezomib is a first-in-class proteasome inhibitor that was originally Food and Drug Administration approved for the treatment of multiple myeloma. In the past few years, off-label use in solid organ transplant recipients has demonstrated its ability to provide plasma cell-targeted therapy in humans. The purpose of this review is to provide an update of recent basic science and clinical results with bortezomib in treating antibody-mediated rejection (AMR) that occurs in solid organ transplant recipients. Recent findings Proteasome inhibitor therapy for AMR in kidney transplant recipients is effective both as primary and as rescue therapy. Optimal responses with proteasome inhibitor therapy are obtained when AMR is diagnosed promptly and early in the posttransplant period. However, proteasome inhibitor therapy for late AMR (i.e., occurring 6 months or later posttransplant) provides less predictable results, likely due to the existence of a substantial bone marrow niche-resident long-lived plasma cell population. Proteasome inhibitor therapy has also recently been shown to provide effective therapy for AMR in heart, and also, transplant recipients. Summary Proteasome inhibitor therapy with bortezomib provides effective treatment for AMR in solid organ transplant recipients. As the first plasma cell-targeted therapy, proteasome inhibitor therapy provides the additional advantage of opening new possibilities for biologically defined plasma cell-targeted therapies.

Background Rejection with hemodynamic compromise (RHC) is associated with high mortality in heart recipients. This study investigates the association between genetic polymorphisms and RHC in pediatric heart recipients. Methods Data from 532 pediatric heart recipients from six centers in the Pediatric Heart Transplant Study were analyzed for time to RHC by recipient race, age at transplantation, and genotype at 13 genetic polymorphisms (TNF-α A-308G, IL-6 G-174C, INF-γ T+874A, IL-10 G-1082A, C-819T, and C-592A; FAS A-670G, FASL C-843T, and ACE I/D; and VEGF A-2578C, C-1451T, C+405G, and -2549 I/D). Results RHC occurred in 126 (23.7%) patients during the study period. Adjusting for age and race, IL-10 G-1082A, FAS A-670G, and ACE I/D genotypes were associated with RHC. IL-10 G-1082A GG genotype was associated with decreased risk of RHC with an adjusted hazard ratio (HR) of 0.49 (95% confidence interval [CI], 0.27-0.90; P=0.020). FAS A-670G AA genotype was associated with increased risk of RHC with an adjusted HR of 1.84 (95% CI, 1.25-2.69; P=0.002). ACE II genotype was associated with decreased risk of RHC with an adjusted HR of 0.58 (95% CI, 0.36-0.95; P=0.031). Conclusions Recipients with a high anti-inflammatory and immune-regulatory genetic profile (high interleukin-10) were protected from RHC. Conversely, recipients with a pro-apoptotic genetic profile (high Fas) or high angiotensin-1-converting enzyme producing genotype were at increased risk of RHC. This represents progress toward understanding the genetic risk factors of posttransplantation outcomes in pediatric heart recipients.

Background. The efficacy of plasma cell targeted therapies for antibody-mediated rejection (AMR) has not been defined in detail. The purpose of this study was to compare early and late acute AMR in terms of immunologic characteristics and responses with proteasome inhibitor (PI) therapy. Methods. Renal transplant recipients with acute AMR were treated with PI-based regimens. Early acute AMR was defined as occurring within 6 months posttransplant. Immunodominant donor-specific antibody (iDSA) was defined as the DSA with the highest level. Results. Results are expressed as early or late acute AMR. Thirty AMR episodes (13 early, 17 late) were treated in 12 and 16 patients. Early but not late AMR was associated with presensitization. Late AMR iDSA levels were higher, and specificities were primarily class II (DQ being most frequent). Early AMR patients demonstrated greater reduction in iDSA at 7, 14, and 30 days and at the posttreatment nadir (81.5%+21.2% vs. 51.4%+27.6%; P

Aim Heart transplant (HTX) candidates with pre-formed anti-HLA antibody (HLA-Ab) have lower transplantation rates and increased waiting time due to positive crossmatches. Anti-angiotensin II type 1 receptor antibody (AT1R-Ab) has recently been associated with allograft loss and antibody-mediated rejection. The aim of the present study was to evaluate: 1) the prevalence of anti-angiotensin receptor 1 antibody (AT1R-Ab) in HTX candidates and 2) the impact of AT1R-Ab on flow cytometry crossmatch (FXM). Methods 115 HTX candidates were tested by ELISA for the presence of AT1R-Ab (U/mL after 1:50 dilution, positive cut-off = 10 U/mL, strong-positive cut-off = 20 U/mL. 43/115 cases were identified with either positive (N = 15) or negative (N = 28) flow crossmatches in the absence of any donor-specific anti-HLA alloantibody (virtual negative crossmatches for HLA antibody). Mean channel shift (MCS) for flow cytometry crossmatches was measured on a 1024 scale. Finally, two index HTX cases with pre-formed AT1R-Ab and positive flow crossmatches are discussed. Results A high proportion of HTX candidates with HLA-Ab exhibited AT1R-Ab (Strongly reactive AT1R-Ab 46/115, 40%; weakly reactive AT1R-Ab 25/115, 21.7%; no AT1R-Ab 44/115, 38.2%). Furthermore, AT1R-Ab levels were significantly higher in patients with a positive versus a negative flow crossmatch (54.81 ± 54.92 versus 9.04 ± 7.36, p = 0.00001, Fig. 1). In addition, MCS was significantly higher in patients with AT1R-Ab versus patients without antibodies (73.95 ± 94.21 versus −51.45 ± 52.07, p = 000003, Fig. 2). In the 15 cases with positive flow crossmatch without HLA-specific antibody, all 15 patients exhibited AT1R-Ab, 11/15 had strong AT1R-Ab, while only 5/25 patients with negative FXM exhibited AT1R-Ab, Chi-square = 24, p = 0.00001). Conclusions More than half of HTX candidates exhibit AT1R-Ab, which can interfere with flow crossmatch interpretation even in the absence of HLA-specific antibodies.

Anti-HLA DSAs are associated with ABMR and graft loss in KT recipients, yet the influence of DSA IgG subclass on outcomes in pediatric KT recipients is not completely understood. We performed a single-center retrospective chart review of pediatric KT recipients with anti-HLA DSAs, aiming to study the association between specific DSA IgG subclasses and graft outcomes, including ABMR and significant graft dysfunction (graft loss or 50% decrease in eGFR). Thirty-six patients (mean age 15.4y) with DSAs initially detected 1 month-14.3 years post-transplantation were followed for a median of 2.8 years. Rates of IgG1, 2, 3, and 4 subclass detection were 92%, 33%, 58%, and 25%, respectively. Twenty-two patients (61%) had clinical ABMR, whereas 19% had subclinical ABMR, and 13 (36%) experienced significant graft dysfunction. Patients with IgG3+ DSAs had a higher risk of graft dysfunction compared with IgG3- patients (52% vs 13%, P = .03). In a multiple Cox proportional regression analysis, the presence of IgG3+ DSA was independently associated with significant graft dysfunction (HR 10.45, 95% CI 1.97-55.55, P = .006). In conclusion, IgG3 subclass DSAs are associated with graft dysfunction and may be useful for risk stratification and treatment decisions in DSA-positive pediatric KT recipients.

Peritubular capillary C4d staining in allograft kidney is an important criterion for antibody-mediated rejection. Whether BK virus infection can result in complement activation is not known. We studied 113 renal allograft biopsies from 52 recipients with a history of BK virus activation. The samples were classified into four groups according to the concurrent detection of BK virus DNA in urine, plasma, and/or biopsy: BK-negative (n=37), viruria (n=53), viremia (n=7), and nephropathy (n=16) groups. The histological semiquantitative peritubular capillary C4d scores in the viremia (0.3+/-0.8) and BK nephropathy (0.6+/-0.9) groups were lower than those in the BK-negative group (1.2+/-1.1, P=0.05 and P=0.06, respectively) and the viruria group (1.2+/-1.1, P=0.04 and P=0.06, respectively). Diffuse or focal peritubular capillary C4d staining was present in 9/76 (12%) and 14/76 (19%) of all samples with concurrent BK virus reactivation (viruria, viremia, and nephropathy). The diagnosis of antibody-mediated rejection could be established in 7/9 (78%) and 5/14 (36%) of these samples, respectively. Diffuse tubular basement membrane C4d staining was restricted to BK nephropathy cases (4/16, 25%). Semiquantitative tubular basement membrane C4d scores were higher in BK nephropathy (1.2+/-1.3) compared with BK-negative (0.05+/-0.3, P=0.017) and viruria (0.0+/-0.0, P=0.008) groups. Bowman's capsule C4d staining was more frequent in BK nephropathy (5/16) compared with the aforementioned groups (2/36 (P=0.023) and 4/51 (P=0.03), respectively). Within the BK nephropathy group, samples with tubular basement membrane stain had more infected tubular epithelial cells (12.1+/-7.6% vs 4.4+/-5.0%, P=0.03) and a trend toward higher interstitial inflammation scores. In conclusion, peritubular capillary C4d staining remains a valid marker for the diagnosis of antibody-mediated rejection in the presence of concurrent BK virus infection. A subset of biopsies with BK nephropathy shows tubular basement membrane C4d staining, which correlates with marked viral cytopathic effect.

Background. Neutrophilic tubulitis accompanied by intratubular neutrophil clusters in the renal allograft is a surrogate marker for urinary tract infection (UTI). Overlapping histologic findings can occur in antibody-mediated rejection, which is characterized by peritubular capillary (PTC) deposition of C4d. This study evaluated the incidence of UTI in biopsies with concurrent neutrophilic tubulitis and PTC C4d staining. Methods. Thirty-three allograft biopsies from 27 patients selected for the presence of simultaneous C4d staining and neutrophilic tubulitis were correlated with urine culture (U/C) results. Results. U/C obtained on the same day as the biopsy confirmed UTI in 13 of 33 (39%) biopsies. Among 20 patients with negative U/C; prior culture results within 10 days of the biopsy were available for nine patients, and 5 of 9 (55%) were positive. Thus, UTI was confirmed in 18 of 33 (54%) biopsies. Biopsy interpretation and clinical management was confounded by changes of concurrent acute cellular rejection and antibody-mediated rejection confirmed by demonstration of donor-specific antibodies. Combined therapy with antibiotics and antirejection medications (ART) was administered to 12 of 18 (67%) patients. Conclusions. Neutrophilic tubulitis accompanied by neutrophil clusters in the tubular lumen is a useful marker of UTI, even in the presence of PTC C4d deposition. Therapeutic response to antibiotics is limited by co-existent T-cell or antibody-mediated rejection and underlying chronic allograft nephropathy.

Background Intestinal retransplantation (Re-ITx) has historically been associated with high morbidity and mortality. Methods The outcomes of all children receiving Re-ITx between 1990 and 2007 at our center were reviewed. Results One hundred seventy-two children received primary intestinal grafts. Fourteen children (8.1%) were retransplanted with 15 grafts. Causes of graft failure were acute cellular rejection (ACR, n=4), liver failure (n=2), chronic rejection (n=3), posttransplant lymphoproliferative disorder (n=1), graft dysmotility or dysfunction (n=3), ACR with severe infection (n=1), and arterial graft aneurysm (n=1). Initial transplants were isolated bowel in nine, liver-bowel in five, and one multivisceral. The mean time of initial graft survival was 34.2 months. Re-ITx was with isolated bowel in two, liver-bowel in four, and multivisceral in nine (four with kidney). Initial immunosuppression was Tac-Pred based in nine and rabbit antithymocyte globulin-Tac based in six cases. Re-ITx was carried out under Tac-Pred in six, rabbit antithymocyte globulin-Tac in eight, and alemtuzumab monoclonal anti-CD52 antibody in one. Ten (71.4%) patients are alive with functioning grafts at a mean current follow-up time of 55.9 months. Four patients died from posttransplant lymphoproliferative disorder, severe ACR, fungal sepsis, and bleeding from pseudoaneurysm, respectively, at a mean time of 5.7 months post-Re-ITx. All surviving patients weaned-off total parenteral nutrition at a median time of 32 days and 90% are off intravenous fluids. Conclusions Improved long-term survival and outcome in pediatric Re-ITx may be attributed to improvements in initial immunosuppression protocols, technical modifications, proper timing, and improved infectious disease monitoring. Careful patient selection and posttransplant management are essential for successful long-term outcome.

Consolidating the information that we have on pharmacogenetics and on cytokine genetics to produce patient-oriented individualized drug regimens is an important challenge in transplantation medicine. Using a multi-variant approach based on genetic profile and other relevant clinical factors a score system may be developed to predict the severity of rejection, infection, or other complications associated with transplantation. The ultimate goal of these studies is to improve patient outcome through individualized drug regimens.

The hallmark of humoral rejection is the presence of subendothelial C4d in the allograft. A simultaneous determination of vascular C4d with soluble C4d in broncho-alveolar lavage fluid (BAL) and circulating anti-human leukocyte antigen (HLA) antibodies (HLA-Ab) has not been reported in lung transplantation.Forty-two consecutive lung-transplant patients were included in this cross-sectional study. The presence and specificity of HLA-Ab was determined at the same frequency with transbronchial biopsies. Soluble C4d levels were measured by enzyme-linked immunosorbent assay in all 42 patients. In a subgroup of 32 patients with available timely matched paraffin-embedded tissue sections, the vascular C4d deposition was also assessed.The presence of HLA-Ab in 16 patients was associated with biopsy-proven acute rejection (10/16 vs. 3/16, P0.01) and increased immunosuppression (13/16 vs. 4/16, P0.005). Pulmonary function was also decreased in patients with HLA-Ab (mean forced expiratory volume in 1 second=49%) when compared with the control group (mean forced expiratory volume in 1 second=66%, P0.05). Nine patients exhibited specific vascular C4d deposition and in eight of nine (89%) cases HLA-Ab were detected, versus 8 of 23 (35%) in C4d-negative patients (P0.05). Soluble C4d in BAL was highly (0.5 microg/mL) elevated in patients with HLA-Ab and vascular C4d and was moderately (0.2 microg/mL) increased in patients with antibodies but C4d-negative. In contrast, only a slight elevation of soluble C4d (0.1 microg/mL) was detected in patients without HLA-specific antibodies.The association of HLA-specific antibodies with vascular C4d deposition and soluble C4d in BAL, in addition to the reduced pulmonary function, might constitute a diagnostic triad for antibody-mediated rejection in lung transplant patients.

Background Little is known about the effect of pre-transplant alloantibody in the pediatric cardiac transplant population. Methods All cardiac listings ( n = 298) at Children's Hospital of Pittsburgh from January 1990 through February 2006 were reviewed to determine the impact of allosensitization on transplantation outcomes. Analysis focused on: (1) wait list outcomes; (2) survival from the time of listing, regardless of subsequent transplantation; (3) post-transplant graft and patient survival; and (4) post-transplant freedom from graft vasculopathy. Institutional policy required a negative, prospective crossmatch for candidates with panel-reactive antibody >20%. Results Alloantibody data were available for 252 (85%) listings. Median time to transplantation was greater for sensitized vs non-sensitized subjects (2.7 months vs 1.3 months; p = 0.02). At 1 year after listing, sensitized subjects had a higher incidence of death (22% vs 8.4%; p = 0.055). Survival at all time-points after listing (regardless of transplantation) was worse for sensitized subjects ( p = 0.04). Although no statistically significant differences in post-transplant graft or patient survival were noted, pre-transplant allosensitization was associated with decreased freedom from graft vasculopathy (hazard ratio [HR] 2.76, 95% confidence interval [CI] 1.18 to 6.45; p = 0.019). Conclusions A policy requiring a negative, prospective crossmatch for highly sensitized candidates is associated with longer wait list time and higher mortality after listing. The development of graft vasculopathy appears to be influenced by the presence of pre-transplant alloantibody.

Objectives Acute and chronic rejection remain unresolved problems after lung transplantation, despite heavy multidrug immunosuppression. In turn, the strong immunosuppression has been responsible for mortality and pervasive morbidity. It also has been postulated to interdict potential mechanisms of alloengraftment. Methods In 48 lung recipients we applied 2 therapeutic principles: (1) recipient pretreatment with antilymphoid antibody preparations (Thymoglobulin [SangStat, Fremont, Calif] or Campath [alemtuzumab; manufactured by ILEX Pharmaceuticals, LP, San Antonio, Tex; distributed by Berlex Laboratories, Richmond, Calif]) and (2) minimal posttransplant immunosuppression with tacrolimus monotherapy or near-monotherapy. Our principal analysis was of the events during the critical first 6 posttransplant months of highest immunologic and infectious disease risk. Results were compared with those of 28 historical lung recipients treated with daclizumab induction and triple immunosuppression (tacrolimus-prednisone-azathioprine). Results Recipient pretreatment with both antilymphoid preparations allowed the use of postoperative tacrolimus monotherapy with prevention or control of acute rejection. Freedom from rejection was significantly greater with Campath than with Thymoglobulin ( P = .03) or daclizumab ( P = .05). After lymphoid depletion with Thymoglobulin or Campath, patient and graft survival at 6 months was 90% or greater. Patient and graft survival after 9 to 24 months is 84.2% in the Thymoglobulin cohort, and after 10 to 12 months, it is 90% in the Campath cohort. There has been a subjective improvement in quality of life relative to our historical experience. Conclusion Our results suggest that improvements in lung transplantation can be accomplished by altering the timing, dosage, and approach to immunosuppression in ways that might allow natural mechanisms of alloengraftment and diminish the magnitude of required maintenance immunosuppression.

Background Multiple drug immunosuppression has allowed the near elimination of rejection, but without commensurate improvements in longterm graft survival and at the cost of quality of life. We have suggested that transplantation outcomes can be improved by modifying the timing and dosage of immunosuppression to facilitate natural mechanisms of alloengraftment and acquired tolerance. Study design Two therapeutic principles were applied for kidney transplantation: pretransplant recipient conditioning with antilymphoid antibody preparations (Thymoglobulin [Sangstat] or Campath [ILEX Pharmaceuticals]), and minimal posttransplant immunosuppression with tacrolimus monotherapy including "spaced weaning" of maintenance doses when possible. The results in Thymoglobulin- (n = 101) and Campath-pretreated renal transplantation recipients (n = 90) were compared with those in 152 conventionally immunosuppressed recipients in the immediately preceding era. Results Spaced weaning was attempted in more than 90% of the kidney transplant recipients after pretreatment with both lymphoid-depleting agents, and is currently in effect in two-thirds of the survivors. Although there was a much higher rate of acute rejection in the Thymoglobulin-pretreated recipients than in either the Campath-pretreated or historic control recipients, patient and graft survival in both lymphoid depletion groups is at least equivalent to that of historic control patients. In the Thymoglobulin-conditioned patients for whom followups are now 24 to 40 months, chronic allograft nephropathy (CAN) progressed at the same rate as in historic control patients. Selected patients on weaning developed donor-specific nonreactivity. Conclusions After lymphoid depletion, kidney transplantation can be readily accomplished under minimal immunosuppression with less dependence on late maintenance immunosuppression and a better quality of life. Campath was the more effective agent for pretreatment. Guidelines for spaced weaning need additional refinement.

This study deals with HLA-mismatched kidney transplants that have been removed following rejection. Sera from 27 patients were screened for HLA-specific antibodies by direct complement-dependent lymphocytotoxicity with HLA-typed cell panels. Circulating donor-specific antibodies were detected in 3 cases (11%) before and in 26 cases (97%) after allograft nephrectomy. These findings demonstrate the production of donor-specific antibodies in patients with rejected transplants, but in most cases, they were undetectable before nephrectomy, because the graft had adsorbed them. With an HLAMatchmaker-based serum analysis program, we observed restricted antibody specificity patterns against amino acid triplet-defined epitopes on donor HLA-A,B antigens. Many donor triplets were non-reactive while others were apparently recognized by antibodies. In some patients, the donor triplet specific antibodies persisted for a long time whereas in many other patients, they became undetectable after a few months. The characterization of the antibody specificity profiles of post-allograft nephrectomy sera is clinically useful in defining criteria of HLA mismatch acceptability for sensitized patients awaiting another transplant. It provides also opportunities for determining the relative immunogenicity of mismatched triplets.

The impact of HLA-specific antibodies is not well established in the acute rejection of lung allografts. Acute rejection represents the most important risk factor for the development of chronic lung allograft dysfunction.We analyzed the pattern of HLA antibodies before and after transplantation in 54 patients, and correlated our data with the presence and frequency of high-grade and persistent-recurrent acute rejection, during the first 18 post-operative months. The diagnosis of acute rejection was based on histologic International Society for Heart and Lung Transplantation (ISHLT)-published criteria.Ten of 54 patients had a positive enzyme-linked immunoassay (ELISA) post-transplantation. In 90% of ELISA-positive patients, the presence of HLA antibodies was associated with persistent-recurrent acute rejections, compared with 34% in the ELISA-negative group (p0.005). There were 28 high-grade acute rejection episodes in the ELISA-positive group, compared with 36 in the ELISA-negative group (p0.0001). The ELISA-positive patients required a greater intensity of immunosuppressive therapy. The patients with ELISA-detected anti-HLA antibodies were at least 3-fold more likely to develop high-grade acute rejection and persistent-recurrent acute rejection, and 7-fold more likely to develop multiple episodes of persistent-recurrent acute rejection, compared with ELISA-negative patients.ELISA-based screening for the development of HLA antibodies is a reliable method that can identify lung transplant recipients at increased risk for high-grade and persistent-recurrent acute rejection. Although bronchiolitis obliterans appears as a point of no return in the evolution of lung-transplanted patients, early detection of risk factors for acute rejection could indirectly decrease the incidence of bronchiolitis obliterans. These lung-transplanted patients may benefit from an altered strategy of immunosuppression.

Antibody-mediated rejection is well established for renal allografts but remains controversial for lung allografts. Cardinal features of antibody-mediated rejection in renal allografts include antibodies to donor human leukocyte antigen (HLA) and evidence for antibody action, such as complement activation demonstrated by C4d deposition. We report a lung allograft recipient with circulating antibodies to donor HLA who failed treatment for acute cellular rejection but responded to therapy for humoral rejection. To address the second criteria for antibody-mediated rejection, we determined whether complement activation could be detected by measuring C4d in bronchoalveolar lavage fluid (BALF) by ELISA. Airway allergen challenge of asthmatics activates the complement pathway; therefore, we used BALF from asthmatics pre- and post-allergen challenge to measure C4d. These controls demonstrated that ELISA could detect increases in C4d after allergen challenge. BALF from the index patient had elevated C4d concomitant with graft dysfunction and anti-donor HLA in the absence of infection. Analysis of BALF from 25 additional lung allograft recipients showed that C4d concentrations >100 ng/mL were correlated with anti-HLA antibodies (p = 0.006), but were also observed with infection and in asyptomatic patients. The findings support the occurrence of anti-HLA-mediated lung allograft rejection and suggest that C4d measurement in BALF may be useful in diagnosis.

Aims Renal transplant (RTX) candidates with pre-formed anti-HLA antibody (HLA-Ab) have lower transplantation rates and increased mortality. Anti-angiotensin II type 1 receptor antibody (AT1R-Ab) has recently been associated with allograft loss and antibody-mediated rejection. The aim of the present study was to evaluate: (1) the prevalence of anti-angiotensin receptor 1 antibody (AT1R-Ab) in RTX candidates with circulating HLA-Ab and (2) AT1R-Ab response to VDS. Methods Thirty-nine patients receiving desensitization therapy had HLA-Ab levels determined by single-antigen bead array (Luminex). Mean fluorescence intensity (MFI) of the strongest HLA-Ab (immunodominant antibody -iDSA) was measured before and after therapy. A successful response was considered when iDSA decreased >50% at nadir versus pre-desensitization. Serum samples were also tested by ELISA for the presence of AT1R-Ab (U/mL after 1:50 dilution), before and after desensitization. Results A high proportion of candidates with HLA-Ab exhibited AT1R-Ab (20/39, 51%). A good response of AT1R-Ab to therapy was observed in 18/20 patients [Figure 1]: 17.4 ± 12.3 pre versus 10.9 ± 13.1 U/mL post therapy, p = 0.0009). iDSA reduction with desensitization was observed in 13/20 patients – 7996 ± 2580 pre versus 4410 ± 2695 MFI post therapy, p = 0.0001). 12/20 patients had both iDSA and AT1R-Ab reduction by therapy, 6/20 responded to AT1R-Ab only, 1/20 responded to iDSA only, and 1/20 was a non-responder. AT1R-Ab levels were more elevated in Caucasians then in African-Americans both before (20.7 ± 14.9 versus 12.3 ± 3.7 U/mL, p = 0.1), and after desensitization (14.7 ± 15.9 versus 5.2 ± 2.9 U/mL, p = 0.1). Conclusions More than half of HLA-sensitized candidates exhibit AT1R-Ab. This initial desensitization experience consistently provided substantial reductions both in HLA-Ab and AT1R-Ab levels in an unselected, highly sensitized kidney transplant candidate population. Download : Download high-res image (380KB) Download : Download full-size image

Aim We have previously reported that more than half of HLA-sensitized renal transplant candidates also exhibit anti-angiotensin II type 1 receptor antibody (AT1R-Ab). AT1R-Ab has been associated with antibody-mediated rejection and worse allograft survival. The aim of the present study was to prospectively compare the natural evolution of AT1R-Ab levels with response to desensitization therapy. Methods Ninety-three patients receiving desensitization therapy (VDS group, N = 23) or without desensitization therapy (non-VDS group, N = 70) had AT1R-Ab levels determined ELISA (U/mL after 1:50 dilution), before and after desensitization (VDS group) or before and after transplantation (non-VDS group). Results Initial AT1R-Ab levels were higher in VDS (17.64 ± 10.62 U/mL) then in non-VDS group (13.01 ± 9.14 U/mL, p Conclusions More than half of HLA-sensitized candidates exhibit AT1R-Ab. This initial desensitization experience consistently provided substantial reductions of AT1R-Ab levels in an unselected, highly sensitized kidney transplant candidate population, reduction that is more pronounced that post-transplant natural antibody dynamics. Download : Download high-res image (104KB) Download : Download full-size image

Background. Granzyme B has been associated with allograft rejection in solid organ transplantation. Single nucleotide polymorphisms (SNPs) in the granzyme B gene might impact its expression. The aims of this study were (1) to establish the frequency of two granzyme B SNPs (A-295G; Q-55R) in pediatric heart transplant (PHTx) recipients and (2) to determine their phenotypic expression in healthy individuals. Methods. Three hundred ninety-six PHTx patients (245 white non-Hispanic, 49 black non-Hispanic, 82 Hispanics, and 20 others) and 52 healthy controls were screened for Q-55R and A-295G. For the control samples, we assessed the frequency of granzyme B positive cells by ELISPOT assay after mitogen stimulation. Results. Among the PHTx recipients, 57% percent of the population carried the Q/Q genotype, whereas 6% were R/R homozygotes. Seven of 49 (14%) black non-Hispanics were R/R homozygotes, whereas 13 of 245 (5%) of white non-Hispanics and 5 of 82 (6%) Hispanics carried the R/R genotype (P=0.02). The A allele frequency of granzyme B A-295G (49.6%) was similar to that of the G allele (50.4%). However, 80% of Black non-Hispanics were A allele carriers compared with 68% of White non-Hispanics (P

Optimal induction regimens for patients at high risk for antibody and/or cell-mediated rejection have not been established. This pilot, prospective, randomized study evaluated addition of B cell/plasma cell-targeting agents to T cell-based induction with rabbit antithymocyte globulin (rATG) in high immunologic risk renal transplant recipients. Patients were randomized to induction with rATG, rATG + rituximab, rATG + bortezomib or rATG + rituximab + bortezomib. Inclusion criteria were: (1) current cytotoxic panel reactive antibody (PRA) ≥20% or peak cytotoxic PRA ≥50% or (2) T or B cell positive flow crossmatch with donor-specific antibody (DSA) or (3) historical positive serologic or cytotoxic crossmatch or DSA to donor or (4) prior allograft loss with more than one acute rejection. Median overall follow-up was 496 days: 1-year and overall acute rejection were 25% and 27.5%, and 25% of patients developed de novo DSA within 1 year. One-year and overall patient survival were 97.5% and 92.5%, and 1-year and overall death-censored allograft survival were 97.5% and 95%. Renal allograft function posttransplant was similar among all arms. Eight of nine cases of peripheral neuropathy were mild, whereas one case was moderate and required a narcotic prescription. In conclusion, addition of rituximab and/or bortezomib to rATG induction has an acceptable safety/toxicity profile in a high immunologic risk renal transplant population.

The results of simultaneous liver-kidney transplants in highly sensitized recipients have been controversial in terms of antibody-mediated rejection and kidney allograft outcomes. This case report provides a detailed and sophisticated documentation of histocompatibility and pathologic data in a simultaneous liver-kidney transplant performed in a recipient with multiple high-titered class I and II antidonor HLA antibodies and a strongly positive cytotoxic crossmatch. Patient received induction with steroids, rituximab, and eculizumab without lymphocyte depleting agents. The kidney transplant was delayed by 6 hours after the liver transplant to allow more time to the liver allograft to “absorb” donor-specific antibodies (DSA). Interestingly, the liver allograft did not prevent immediate antibody-mediated injury to the kidney allograft in this highly sensitized recipient. Anti-HLA single antigen bead analysis of liver and kidney allograft biopsy eluates revealed deposition of both class I and II DSA in both liver and kidney transplants during the first 2 weeks after transplant. Afterward, both liver and kidney allograft functions improved and remained normal after a year with progressive reduction in serum DSA values.

Background A prospective intermediate-term evaluation of toxicities associated with bortezomib therapy for antibody-mediated rejection (AMR) and desensitization was conducted. Methods Patients were graded for bortezomib-related toxicities: hematologic and gastrointestinal toxicities by Common Terminology Criteria for Adverse Events and peripheral neuropathy by modified Functional Assessment of Cancer Therapy questionnaire and Common Terminology Criteria for Adverse Events. Results Fifty-one patients treated for AMR and 19 patients treated for desensitization received 96 bortezomib cycles (1.3 mg/m(2) ×4 doses); mean (SD) follow-up was 16.3 (9.0) months. Patients treated for AMR and patients treated for desensitization were similar in age, gender, ethnicity, and baseline peripheral neuropathy. Patients treated for AMR received a mean (SD) of 4.9 (2.0) bortezomib doses in 1.3 (0.5) cycles; and patients treated for desensitization, a mean of 7.3 (1.6) doses in 1.8 (0.4) cycles. Prevalence of diabetes and anemia were higher at baseline in patients treated for AMR. In the AMR cohort, two cases of cytomegalovirus infection, two cases of BK virus infection, and one case of Epstein-Barr virus infection were observed. No cases of viral infection were observed in the desensitization cohort. Malignancies were not observed. Significant bortezomib toxicities included anemia and peripheral neuropathy, which were manageable. Anemia was more common in patients treated for AMR; and peripheral neuropathy, more common in patients treated for desensitization. Conclusions Bortezomib-related toxicities in kidney transplant candidates and recipients are low in incidence and severity and vary based on treatment population.

Background Single-nucleotide polymorphisms (SNPs) associated with active cytomegalovirus (CMV) infections after lung transplantation have not been identified. Methods SNPs associated with varying levels of interferon (IFN)-γ (+874T/A), tumor necrosis factor-α (−308G/A), interleukin-10 (−1082G/A, −819C/T, −592C/A) and interleukin-6 (−174G/C) were characterized for 170 Caucasian lung transplant recipients who received alemtuzumab induction and valganciclovir prophylaxis against CMV. Results Patients were followed for a median of 34 months post-transplant, and 66% (113 of 170), 24% (40 of 170) and 10% (17 of 170) had no CMV infection, CMV viremia and CMV disease, respectively. Median times to CMV viremia and disease were 7 and 10 months, respectively. For each gene, there was no significant deviation from Hardy–Weinberg equilibrium. Independent risk factors for the development of CMV disease were IFN-γ +874 T/T genotype (associated with high levels of IFN-γ production), CMV donor-positive/recipient-negative (D + /R − ) serostatus and acute cellular rejection requiring augmented immunosuppression ( p = 0.001, 0.003 and 0.049, respectively). The association between IFN-γ +874 T/T genotype and CMV disease was most striking among R + patients ( p = 0.02). D + /R − serostatus was also a significant risk factor for CMV viremia ( p = 0.0005). IFN-γ +874 T/T genotype was associated with significantly lower peak CMV viral loads ( p = 0.03). There were no associations between tumor necrosis factor-α, interleukin-10 or interleukin-6 SNPs and CMV infections. Conclusion A genetic predisposition to elevated IFN-γ levels may play a dual role in controlling active CMV infection among lung transplant recipients receiving alemtuzumab induction and valganciclovir prophylaxis, limiting the extent of viral replication in serum but increasing the risk of CMV disease.

Late infections are common causes of morbidity and mortality after pediatric heart transplantation. In this multicenter study from 6 centers, we investigated the association between genetic polymorphisms (GPs) in immune response genes and late post-transplantation infections in 524 patients.Late infection was defined as a clinical infectious process occurring60 days after transplantation and requiring hospitalization, intravenous antimicrobial therapy, or a life-threatening infection requiring oral therapy. All patients provided a blood sample for GP analyses of 18 GPs in cytokine, growth factor, and effector molecule genes by single specific primer-polymerase chain reaction and/or sequencing. Significant associations in univariable analyses were tested in multivariable Cox regression models.Late infection was common, with 48.7% of patients experiencing ≥ 1 late infection, 25.2% had ≥ 1 late bacterial infection, and 30.5% had ≥ 1 late viral infection. Older age at transplantation was a protective factor for late infection, both bacterial and viral (hazard ratio [HR] 0.89-0.92 per 1-year age increase, p0.001). Adjusting for age, race, and transplant etiology, late bacterial infection was associated with HMOX1 A+326G AG and GG genotypes (HR, 2.41, 95% confidence interval [CI] 1.35-4.30; p = 0.003) and GZMB A-295G AA genotype (HR, 1.47; 95% CI; 1.03-2.1; p = 0.036). Late viral infection was associated with FAS A-670G GG genotype (HR, 1.42; 95% CI, 1.00-2.00; p = 0.050) in the adjusted model and with CTLA4 A+49G AA and AG genotypes (HR, 1.49; 95% CI, 1.02-2.19; p = 0.041) in univariable analysis.We found an association between late bacterial infection and GP of HMOX1, which may control macrophage activation. A weaker association was also found between late viral infection and GP of CTLA4, a regulator of T-cell activation. This represents progress toward understanding the clinical and genetic risk factors of outcomes after transplantation.

Background Mycophenolate mofetil (MMF) is an effective and commonly used immunosuppressant but has frequent adverse events. Genetic polymorphisms may contribute to variability in MMF efficacy and related complications. In this study we explore the distribution frequencies of common single nucleotide polymorphisms (SNPs) of IMPDH1, IMPDH2 and ABCC2 and investigate whether these SNPs influence MMF adverse events in 59 pediatric heart recipients. Methods Genotypes were assessed by TaqMan analysis of: ABCC2 rs717620; IMPDH2 rs11706052; and IMPDH1 rs2288553, rs2288549, rs2278293, rs2278294 and rs2228075. Gastrointestinal (GI) intolerance was defined as diarrhea, vomiting, nausea or abdominal pain requiring dose-holding for >48 hours or MMF discontinuation. Bone marrow toxicity was evaluated using Common Terminology Criteria for Adverse Events Version 3 (CTCAE). Results GI intolerance occurred in 21 patients, and 21 had bone marrow toxicity. The ABCC2 rs717620 A variant was significantly associated with GI intolerance leading to drug discontinuation ( p IMPDH1 rs2278294 A variant and rs2228075 A variant were also associated with greater GI intolerance ( p = 0.029 and p = 0.002, respectively). The IMPDH2 rs11706052 G variant was associated with more frequent neutropenia requiring dose-holding ( p = 0.046). Conclusions In this small sample of pediatric heart transplant patients receiving MMF, ABCC2 , IMPDH1 and IMPDH2 SNPs were associated with MMF GI intolerance and bone marrow toxicity. Thus, genetic polymorphisms may directly influence MMF adverse events.

Demographic and clinical risk factors may only partially predict short- and long-term outcomes after thoracic transplantation. The interindividual variability seen in rejection profiles could be related to the recipient's or donor's genetic background. Rejection, either acute or chronic, elicits an alloimmune response that involves a complex network of cytokines, growth factors, adhesion molecules, and other molecules, which may modulate the immune response toward rejection or, conversely, mediate graft acceptance. Herein, the authors discuss the current evidence regarding the importance of genetic polymorphisms as independent predictors of allograft outcome. They believe that pretransplant genotype profiling of patients, in combination with other relevant clinical information, might be useful to predict the risk for posttransplant adverse events and also to facilitate the implementation of individualized immunosuppression.

Diffuse C4d deposition in peritubular capillaries is a well-recognized marker of antibody-mediated rejection. The significance of staining patterns that are focal or affect non-peritubular capillary compartments is less well defined. Paired frozen section and paraffin-embedded tissue stains were performed in 52 kidney allograft biopsies, and correlated with clinicopathologic parameters. Diffuse peritubular capillary C4d deposits were more often seen in frozen sections (22/52, 43% frozen tissue vs 10/52, 19% paraffin-embedded tissue), whereas focal staining was observed more frequently within paraffin sections (13/52, 25% paraffin-embedded tissue vs 7/52, 14% frozen tissue). In biopsies taken from patients with a history of donor-specific antibodies, diffuse, focal and negative peritubular capillary C4d staining patterns were seen in 11/14 (79%), 1/14 (7%) and 2/14 (14%) of frozen biopsies vs 5/14 (36%), 6/14 (43%) and 3/14 (21%) of paraffin-embedded biopsies. Transplant glomerulopathy score in paraffin-embedded biopsies was higher in specimens with vs without glomerular basement membrane C4d staining (1.5+/-0.8 vs 1.0+/-0.6, P=0.03). Tubular basement membrane staining was present in 4% paraffin-embedded and 48% frozen specimens independent of tubular atrophy. Arteriolar hyalinosis score in paraffin-embedded specimens was higher in biopsies with vs those without arteriolar C4d deposits (1.3+/-0.9 vs 0.9+/-0.8, P=0.04). Arterial staining was unrelated to the degree of intimal thickening. In conclusion, peritubular capillary deposits correlate well with circulating donor-specific antibody. For paraffin-embedded tissue, combining the results of focal and diffuse staining allows a diagnostic sensitivity comparable to diffuse staining in frozen tissue. Finally, C4d deposits preferentially in lesions of chronic transplant glomerulopathy and arteriolar hyalinosis.

BACKGROUND. Antibody preconditioning with tacrolimus monotherapy has allowed many renal allograft recipients to be maintained on spaced weaning. METHODS. Of 279 renal allograft recipients transplanted between March 2003 and December 2004, 222 (80%) had spaced weaning (i.e., reduction of tacrolimus monotherapy dosing to every other day, three times a week, twice a week, or once a week) attempted. Routine monitoring for donor-specific antibody (DSA) was begun in September 2004. Mean follow-up is 34±6.5 months after transplantation and 26±8.1 months after the initiation of spaced weaning. RESULTS. One hundred and twenty-two (44%) patients remained on spaced weaning. One- and 2-year actual patient/graft survival was 99%/99%, and 97%/96%. Fifty-six (20%) patients experienced acute rejection after initiation of spaced weaning. One- and 2-year actual patient/graft survival was 100%/98%, and 94%/78%. Forty-two (15%) patients with stable renal function had spaced weaning stopped because of the development of DSA, which disappeared in 17 (40%). One- and 2-year actual patient and graft survival was 100% and 100%. CONCLUSION. Adult renal transplant recipients who are able to be maintained on spaced weaning have excellent outcomes. Patients with stable renal function who have reversal of weaning because of the development of DSA also have excellent outcomes. Routine monitoring for DSA may allow patients to avoid late rejection after spaced weaning. © 2008 Lippincott Williams & Wilkins, Inc.

BACKGROUND Focal PTC C4d staining in acute renal allograft rejection has not been studied extensively. METHODS Renal allograft biopsies performed after October 2003, representing the first episode of acute rejection (AR) in recipients with > or = 12 months follow-up postbiopsy, were assessed for extent of C4d and correlated with morphology, ELISA screen, donor-specific antibodies (DSA), response to treatment, and outcome. RESULTS In 106 biopsies (16 C4d-diffuse; 24 C4d-focal; 66 C4d-negative), there were no differences among the three groups in terms of timing or grade of AR, creatinine level, tacrolimus level, and grade of interstitial fibrosis/tubular atrophy or graft loss. The C4d-diffuse group was significantly associated with less tubulitis (P=0.0021), and more chronic allograft arteriopathy (P=0.0527). Incomplete response to steroid therapy was more frequent in C4d-diffuse/focal compared with negative cases (P=0.0492). DSA frequency within 1 year of AR was highest in the C4d-diffuse (94%), followed by C4d-focal (38%), and C4d-negative (17%) groups (P