Correlation of Donor-derived Cell-free DNA With Histology and Molecular Diagnoses of Kidney Transplant Biopsies.

BACKGROUND: Circulating donor-derived cell-free DNA (cfDNA), a minimally invasive diagnostic tool for kidney transplant rejection, was validated using traditional histology. The molecular microscope diagnostic system (MMDx) tissue gene expression platform may provide increased precision to traditional histology. METHODS: In this single-center prospective study of 208 biopsies (median = 5.8 mo) posttransplant, we report on the calibration of cfDNA with simultaneous biopsy assessments using MMDx and histology by area under the curve (AUC) analyses for optimal criterion, as well as for, previously published cfDNA cutoffs ≤ 0.21% to "rule-out" rejection and ≥1% to "rule-in" rejection. RESULTS: There were significant discrepancies between histology and MMDx, with MMDx identifying more antibody-mediated rejection (65; 31%) than histology (43; 21%); the opposite was true for T cell-mediated rejection [TCMR; histology: 27 (13%) versus MMDx: 13 (6%)]. Most of the TCMR discrepancies were seen for histologic borderline/1A TCMR. AUC for cfDNA and prediction of rejection were slightly better with MMDx (AUC = 0.80; 95% CI: 0.74-0.86) versus histology (AUC = 0.75; 95% CI: 0.69-0.81). A cfDNA ≤ 0.21% had similar sensitivity (~91%) to "rule-out" rejection by histology and MMDx. Specificity was slightly higher with MMDx (92%) compared with histology (85%) to "rule-in" rejection using cfDNA criterion ≥1%. Strong positive quantitative correlations were observed between cfDNA scores and molecular acute kidney injury for both "rejection" and "nonrejection" biopsies. CONCLUSIONS: Molecular diagnostics using tissue gene expression and blood-based donor-derived cell-free DNA may add precision to some cases of traditional histology. The positive correlation of cfDNA with molecular acute kidney injury suggests a dose-dependent association with tissue injury irrespective of rejection characteristics.

Outcomes of short-duration antiviral prophylaxis for hepatitis C positive donor kidney transplants.

Trials describing 4- to 12-week courses of direct-acting antiviral drugs (DAAs) to treat hepatitis C virus (HCV) transmission from infected donors to uninfected kidney transplant recipients (D+/R- transplants) may be limited in "real-world" application by costs and delayed access to DAAs. We previously reported HCV transmission of 13% among D+/R- transplants with 2- to 4-day pangenotypic sofosbuvir/velpatasvir (SOF/VEL) perioperative prophylaxis, where one patient with HCV transmission was a nonresponder to first-line full-course DAA. Here, we report new data with a 7-day prophylaxis protocol (N = 50), as well as cumulative treatment and outcome data on all HCV D+/R- transplants (N = 102). Overall, nine patients (9/102; 9%; 95% CI: 5%-16%) developed HCV transmission, with a significant decline noted in the 7-day group (2/50; 4%; 95% CI: 0%-13%) compared with 2- to 4-day prophylaxis (7/52; 13%; 95% CI: 5%-25%). All patients with HCV transmission achieved sustained virologic response post full-course therapy (including one nonresponder from initial trial). A 1:1 matched analysis (N = 102) with contemporary HCV D-/R- transplants (controls) showed that although the pretransplant wait time was significantly shorter for D+/R- compared with D-/R- (mean: 1.8 vs. 4.4 years; p < .001), there were no differences in infections, rejection, development of de novo donor-specific antibody, or transplant outcomes up to 6 months of transplant.

Impact of Belatacept Conversion on Renal Function, Histology, and Gene Expression in Kidney Transplant Patients With Chronic Active Antibody-mediated Rejection.

BACKGROUND: Here, we present our initial experience with a prospective protocol of belatacept conversion in patients with chronic active antibody-mediated rejection (caAMR) and a high degree of chronicity at the time of diagnosis. METHODS: We converted 19 patients (mean age, 45 ± 12 y) with biopsy-proven caAMR from tacrolimus to belatacept at a median of 44 months post-kidney transplant. RESULTS: At a median of 29 months (interquartile range, 16-46 mo) postconversion, death-censored graft and patient survivals were 89% and 95%, respectively. When compared to a 1:2 propensity-matched control cohort from the INSERM U970 registry maintained on calcineurin inhibitor, the belatacept group had progressive improvement (P = 0.02) in estimated glomerular filtration rate from a mean of 33.9 ± 10 at baseline to 37.8 ± 13 at 6 months and 38.5 ± 12 mL/min/1.73 m2 at 12 months postconversion, as compared to a steady decline noted in the controls (36.2 [baseline] → 33.1 [6 mo] → 32.7 mL/min/1.73 m2 [12 mo] of follow-up). A paired histologic comparison of preconversion and postconversion (performed at median 9.5 mo postconversion) biopsies showed no worsening in microvascular inflammation or chronicity. The paired tissue gene expression analysis showed improved mean total rejection score (0.68 ± 0.26-0.56 ± 0.33; P = 0.02) and a trend toward improved antibody-mediated rejection score (0.64 ± 0.34-0.56 ± 0.39; P = 0.06). CONCLUSIONS: Here, we report that in patients diagnosed with caAMR who were not subjected to intensive salvage immunosuppressive therapies, isolated belatacept conversion alone was associated with stabilization in renal function. These results are bolstered by molecular evidence of improved inflammation.

Coronavirus Disease 2019 Viremia, Serologies, and Clinical Course in a Case Series of Transplant Recipients.

Here we report a single-center cohort of 6 patients (4 kidney only, and 2 simultaneous liver/kidney transplants) diagnosed with COVID-19 at a median of 1.9 years (range = 0.2-9.3 years) post transplant. Five (of 6) patients required inpatient admission, 2 patients (mortality = 33%) died. Among those with mortality, an increased concentration of inflammatory biomarkers (interleukin-6 and C-reactive protein) was noted with a lack of response to interleukin-6 blockade, remdesivir, and/or convalescent plasma. None of the kidney-only transplants (4/6; 67%) had elevation in plasma donor-derived cell-free DNA above the previously published cut-off of 1%, suggesting absence of significant allo-immune injury. Four (of 5) admitted patients had detectable SARS-CoV-2 (severe acute respiratory syndrome-coronavirus 2) in blood on samples obtained at/during hospitalization. Of the 4 discharged patients, 2 patients with undetectable virus on repeat nasopharyngeal swabs had seroconversion with positive SARS-CoV-2 IgG formation at 30 to 48 days post infection. One patient had prolonged shedding of virus on nasopharyngeal swab at 28 days post discharge despite lack of symptoms. In this preliminary report, we find that immunocompromised transplant patients had higher rates of RNAemia (67%) than reported in the general population (15%), seeming absence of allo-immune injury despite systemic inflammation, and formation of IgG overtime after recovery from infection.

Elevated AT1R Antibody and Morbidity in Patients Bridged to Heart Transplant Using Continuous Flow Left Ventricular Assist Devices.

BACKGROUND: We studied longitudinal levels of angiotensin-II type 1 receptor antibody (AT1R-Ab) and their effects on adverse events (death, treated rejection and cardiac allograft vasculopathy) in patients who were bridged to heart transplant using a continuous flow left ventricular assist device (LVAD). METHODS AND RESULTS: Sera of 77 patients bridged to heart transplant (from 2009 to 2017) were tested for AT1R-Ab and CRP before and after LVAD. Elevated AT1R-Ab was defined as >10.0 U/mL. The median follow-up after transplant was 3.6 years (interquartile range, 2.2-5.6 years). After LVAD, AT1R-Ab levels increased from baseline and remained elevated until transplant. Freedom from adverse events at 5 years was lower in those with elevated AT1R-Ab levels at time of transplant. In an adjusted, multivariable Cox analysis, an AT1R-Ab level of >10 U/mL was associated with developing the primary end point (adjusted hazard ratio 3.4, 95% confidence interval 1.2-9.2, P = .017). Although C-reactive protein levels were high before and after LVAD placement, C-reactive protein did not correlate with AT1R-Ab. CONCLUSIONS: In LVAD patients bridged to heart transplant, an increased AT1R-Ab level at time of transplant was associated with poor outcomes after heart transplant. Post-LVAD AT1R-Ab elevations were not correlated with serum markers of systemic inflammation. Larger studies are needed to examine the pathologic role of AT1R-Ab in heart transplant.

Lack of Histological and Molecular Signature Response to Tocilizumab in Kidney Transplants with Chronic Active Antibody Mediated Rejection: A Case Series.

Background: Traditional therapies for caAbMR have unclear efficacy with significant side effects in recipients of kidney transplants (KTs). A recent single-center case series suggested tocilizumab (TCZ) could stabilize renal function and improve microvascular inflammation. Here we report our findings of the use of TCZ in patients with caAbMR. Methods: Ten adult recipients of KTs with biopsy-proven caAbMR were treated with TCZ at 8 mg/kg per month. Patients were monitored for adverse events, and therapy was interrupted in the setting of serious infections. Six patients (60%) underwent post-treatment biopsies. Results: Patients (mean age of 43 years) were initiated on TCZ at a median of 36 months post-KT. A majority of patients were black (70%), underwent regrafts (40%), and were sensitized (mean cPRA=41%). Patients received a median of six doses of TCZ (range=3-10). At a median follow-up of 12 months (range=8-24 months), renal function did not show improvement (mean eGFR, 42±18 ml/min per 1.73 m2 to 37±24 ml/min per 1.73 m2; P=0.27). The slope of decline in eGFR remained unchanged (-0.14±0.9 to -0.33±1.1; P=0.25). There was no improvement in mean MVI (g+ptc) (4.8±1.4 to 4.2±2.0; P=0.39) scores or Molecular Microscope Diagnostic System (MMDx) AbMR scores (0.79±0.17 to 0.78±0.26; P=0.86). There was a numeric worsening of chronicity (ci+ct) scores (2.5±0.8 to 3.3±1.7; P=0.38) and MMDx atrophy fibrosis scores (0.36±0.24 to 0.58±0.15; P=0.21). Patient survival was 90%, with one patient death due to complications from a hip infection. Overall death-censored graft survival was 80%, with two graft losses in patients who had recurrent infections requiring hospitalization. Conclusions: In this early experience, we report a lack of efficacy and toxicity with the use of TCZ for caAbMR. Prospective clinical trials are needed to clarify the role of IL-6 blockade and the possibility of increased incidence of infections in patients with caAbMR who are treated with TCZ.

Killer Immunoglobulin-Like Receptor-Ligand Interactions Predict Clinical Outcomes following Unrelated Donor Transplantations.

Killer immunoglobulin-like receptor (KIR) and KIR ligand (KIRL) interactions play an important role in natural killer (NK) cell-mediated graft-versus-leukemia effect following hematopoietic cell transplantation (HCT). However, there is considerable heterogeneity in the KIR gene and KIRL content in individuals, making it difficult to estimate the full clinical impact of NK cell reconstitution following HCT. Here we present a novel adaptive mathematical model designed to quantify these interactions to better assess the influence of NK cell-mediated alloreactivity on transplant outcomes. Ninety-eight HLA- matched unrelated donor (URD) HCT recipients were studied retrospectively. The KIR-KIRL interactions were quantified using a system of matrix equations. Unit values were ascribed to each KIR-KIRL interaction, and the directionality of interactions was denoted by either a positive (activating) or negative (inhibition) symbol; these interactions were then summed. The absolute values of both the missing KIRL and inhibitory KIR-KIRL interactions were significantly associated with overall survival and relapse. These score components were initially used to develop a weighted score (w-KIR score) and subsequently a simplified, nonweighted KIR-KIRL interaction score (IM-KIR score). Increased w-KIR score and IM-KIR score were predictive of all-cause mortality and relapse (w-KIR score: hazard ratio [HR], .37 [P = .001] and .44 [P = .044], respectively; IM-KIR score: HR, .5 [P = .049] and .44 [P = .002], respectively). IM-KIR score was also associated with NK cell reconstitution post-HCT. KIR-KIRL interactions as reflected by the w-KIR and IM-KIR scores influence both relapse risk and survival in recipients of HLA-matched URD HCT with hematologic malignancies.

Ultra-short duration direct acting antiviral prophylaxis to prevent virus transmission from hepatitis C viremic donors to hepatitis C negative kidney transplant recipients.

We conducted an adaptive design single-center pilot trial between October 2017 and November 2018 to determine the safety and efficacy of ultra-short-term perioperative pangenotypic direct acting antiviral (DAA) prophylaxis for deceased hepatitis C virus (HCV)-nucleic acid test (NAT) positive donors to HCV negative kidney recipients (D+/R-). In Group 1, 10 patients received one dose of SOF/VEL (sofusbuvir/velpatasvir) pretransplant and one dose on posttransplant Day 1. In Group 2A (N = 15) and the posttrial validation (Group 2B; N = 25) phase, patients received two additional SOF/VEL doses (total 4) on Days 2 and 3 posttransplant. Development of posttransplant HCV transmission triggered 12-week DAA therapy. For available donor samples (N = 27), median donor viral load was 1.37E + 06 IU/mL (genotype [GT]1a: 70%; GT2: 7%; GT3: 23%). Overall viral transmission rate was 12% (6/50; Group 1:30% [3/10]; Group 2A:13% [2/15]; Group 2B:4% [1/25]). For the 6 viremic patients, 5 (83%) achieved sustained virologic response (3 with first-line DAA therapy; and two after retreatment with second-line DAA). At a median follow-up of 8 months posttransplant, overall patient and allograft survivals were 98%, respectively. The 4-day strategy reduced viral transmission to 7.5% (3/40; 95% confidence interval [CI]: 1.8%-20.5%) and could result in avoidance of prolonged posttransplant DAA therapy for most D+/R - transplants.

Antibody mediated rejection due to de-novo DSA causing venous thrombosis of pancreas allograft - A case report.

This case describes a 34year old female who underwent an HLA identical living donor kidney transplant with a positive flow cytometric crossmatch (FCXM), but without any donor specific antibody (DSA). Tests to detect non-HLA antibody and autoantibody were negative. Allograft functioned well without rejection. She later received a pancreas allograft, again with a weakly positive FCXM, without DSA. After good initial graft function, she developed hyperglycemia six weeks posttransplant. Cross-sectional imaging demonstrated non-enhancing pancreas allograft with new vein thrombosis. She underwent transplant pancreatectomy, the explant pathology demonstrated changes consistent with severe acute antibody mediated rejection (AMR) causing thrombosis of the pancreas allograft. She had also developed several de-novo class-I DSAs at this time. Despite extensive testing, we could not identify a causative antibody for the initial positive FCXMs or its role in the eventual rejection of the pancreas allograft.

Circulating angiotensin type II receptor: Possible marker for antibody mediated rejection after renal transplantation?

BACKGROUND: Presence of antibody [Ab] against angiotensin receptor [AT1R] indicates heightened risk for antibody mediated rejection [AMR] after transplantation but is insufficient as a marker. We speculated AT1R might be released systemically because of AMR and might be a useful biomarker. METHODS: AT1R was measured in blood from 73 Normals and 72 renal patients pre- and post-transplantation. Patients were stratified as AMR-free [Gp1], AMR<1yr [Gp2] and AMR>1yr [Gp3]. RESULTS: AT1R was higher [13±26vs.367±537, p<0.01)] and more prevalent [20% vs. 92%, p<0.01] among renal patients than Normals. Pretransplant levels were similar [p=ns] between groups. One-year posttransplant levels approached [p<0.01] normalcy for Gps1+3 but spiked during AMR and remained elevated [155±58, p<0.01] for 50% Gp2 patients. One-year AT1R levels were higher among subsequent graft failures than surviving grafts [171±267vs. 38±50, p<0.01]. CONCLUSIONS: Pretransplant AT1R was abnormally elevated: possibly indicating ongoing tissue injury. Pretransplant AT1R didn't predict risk for AMR. However, AT1R spiked during early AMR and sustained elevations were associated with poorer outcomes.

Perioperative Desensitization Improves Outcomes Among Crossmatch Positive Recipients of Deceased Donor Renal Transplants.

CONTEXT: Graft failure due to chronic rejection is greater among renal transplant patients with donor-specific antibody (DSA) than among DSA-free patients. For patients dependent on deceased donor transplantation, preoperative desensitization to eliminate DSAs may be impractical. We speculated that perioperative desensitization might eliminate preexisting DSAs and prevent de novo DSAs and improve graft outcomes. We report that brief perioperative desensitization using either intravenous immunoglobulin (IVIG) or plasmapheresis/IVIG (PP/IVIG) treatment improves clinical outcomes among patients with positive crossmatches. DESIGN: Immediately following deceased donor transplantation, 235 renal recipients were assigned points for PRA and flow crossmatches (FCXM): delayed graft function (DGF) ≤ 1 point received standard therapy; 2 points received high-dose IVIG; and ≥3 points received PP/IVIG. The DSAs were serially monitored by single antigen bead luminex for 1 year. Five-year clinical outcomes were determined from the chart review. RESULTS: All desensitized patients had preoperatively positive FCXM with DSA. Rejection was more common (P < .05) among desensitized than nonsensitized groups. However, overall graft survivals were similar between the groups (P = not significant) and superior to historic untreated patients (P < .05). Treatment with PP/IVIG more effectively eliminated preexisting DSAs (67% vs 33%, P < 0.05) than IVIG, but neither regimen prevented de novo formation of DSA (20%, P = not significant). Graft survival was >90% in all desensitizated patients with DSA elimination as well as PP/IVIG patients with residual DSA. In contrast, IVIG patients with persistent DSA had poorer graft survival (45%, P < .05). CONCLUSION: Preemptive perioperative desensitization improved overall graft survival of sensitized patients compared to historic untreated patients. Plasmapheresis/IVIG had greater impact on DSA eradication and graft survival than IVIG alone.

Pre-transplant phospholipase A2 receptor autoantibody concentration is associated with clinically significant recurrence of membranous nephropathy post-kidney transplantation.

Previous studies that have assessed the association of pre-transplant antiphospholipase A2 receptor autoantibody (PLA2R-Ab) concentration with a recurrence of membranous nephropathy (rMN) post-kidney transplant have yielded variable results. We tested 16 consecutive transplant patients with a history of iMN for pre-transplant PLA2R-Ab. Enzyme-linked immunosorbent assay titers (Euroimmun, NJ, USA) >14 RU/mL were considered positive. A receiver operating characteristic (ROC) analysis was performed after combining data from Quintana et al. (n = 21; Transplantation February 2015) to determine a PLA2R-Ab concentration which could predict rMN. Six of 16 (37%) patients had biopsy-proven rMN at a median of 3.2 yr post-transplant. Of these, five of six (83%) had a positive PLA2R-Ab pre-transplant with a median of 82 RU/mL (range = 31-1500). The only patient who had rMN with negative PLA2R-Ab was later diagnosed with B-cell lymphoma. One hundred percent (n = 10) of patients with no evidence of rMN (median follow-up = five yr) had negative pre-transplant PLA2R-Ab. In a combined ROC analysis (n = 37), a pre-transplant PLA2R-Ab > 29 RU/mL predicted rMN with a sensitivity of 85% and a specificity of 92%. Pre-transplant PLA2R-Ab could be a useful tool for the prediction of rMN. Patients with rMN in the absence of PLA2R-Ab should be screened for occult malignancy and/or alternate antigens.

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.

Pregnancy-related allograft rejection following heart transplant.

Current recommendations do not discourage pregnancy in stable, orthotopic heart transplant (OHT) recipients who are more than 1 year posttransplant, although a highly specialized level of care with a multidisciplinary team is recommended. These patients may incur significant risk to themselves, their allograft, and/or their fetuses. Recognition and treatment of posttransplant complications in pregnancy also may be difficult. Although the risk of recurrent pregnancies in patients with peripartum cardiomyopathy (PPCM) is well defined, the risk of pregnancy after a PPCM patient has undergone OHT is unknown. A case of severe allograft rejection in a woman with a history of PPCM who became pregnant nearly 3 years after OHT is presented and her subsequent management is described. The data available on pregnancy after transplant are based on case reports, registry data, and reviews. The decision to become pregnant should be preceded by an extensive discussion including the patient, her partner, her obstetrician, and the transplant team, reviewing potential risks to her health as well as to her allograft and the fetus. Providers should be clear that many questions pertaining to pregnancy after transplant remain unanswered, and the patient should be comfortable going forward in this situation.

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.

Graft-versus-host disease after solid organ transplantation: a single center experience and review of literature.

BACKGROUND: Graft-versus-host disease (GVHD) is an uncommon cause of morbidity and mortality after solid organ transplantation that is most likely under-diagnosed. We describe our single center experience with three cases of GVHD diagnosed over a period of 15 years in a total of 2,271 solid organ transplant recipients. CASE REPORTS: We describe three case reports: (1) a 3-week old neonate who developed GVHD 16 months after living-related liver transplant, (2) a 14-year old adolescent who developed GVHD 4 months following an unrelated cadaveric pancreas transplant and; (3) a 27-year old male who developed GVHD 18 days after simultaneous kidney-pancreas transplant from an unrelated donor. GVHD was confirmed through skin biopsies, engraftment profile from bone marrow biopsy and variable number tandem repeat analysis. Treatment strategies included use of corticosteroids and sirolimus monotherapy, corticosteroids and mesenchymal stromal cell therapy and reduction of immunosuppression. We observed that African-American race, sexual and HLA mismatching and cytomegalovirus infection may be high risk factors for development of GVHD following solid organ transplant. CONCLUSIONS: GVHD continues to be a rare but fatal complication following solid organ transplantation that demands a high index of clinical suspicion for diagnosis and management. Future approaches may focus on early recognition of risk factors and improving treatment protocols using a combination of mesenchymal stromal cell transplantation with pharmacotherapy.

Surveillance of alloantibodies after transplantation identifies the risk of chronic rejection.

The monitoring of the levels of alloantibodies following transplantation might facilitate early diagnosis of chronic rejection (CR), the leading cause of renal allograft failure. Here, we used serial alloantibody surveillance to monitor patients with preoperative positive flow cytometric crossmatch (FCXM). Sixty-nine of 308 renal transplant patients in our center had preoperative positive FCXM. Blood was collected quarterly during the first postoperative year and tested by FCXM and single antigen bead luminometry, more sensitive techniques than complement-dependent cytotoxic crossmatching. Distinct post-transplant profiles emerged and were associated with different clinical outcomes. Two-thirds of patients showed complete elimination of FCXM and solid-phase assay reactions within 1 year, had few adverse events, and a 95% 3-year graft survival. In contrast, the remaining third failed to eliminate flow FCXM or solid-phase reactions directed against HLA class I or II antibodies. The inferior graft survival (67%) with loss in this latter group was primarily due to CR. Thus, systematic assessment of longitudinal changes in alloantibody levels, either by FCXM or solid-phase assay, can help identify patients at greater risk of developing CR.

A novel post-transplant alloantibody surveillance and intervention strategy that improves graft outcomes in sensitized renal transplant recipients.

Chronic rejection, the leading cause of renal graft failure, is mediated by alloantibody graft destruction. Monitoring alloantibodies posttransplant might facilitate early diagnosis of alloantibody mediated graft destruction and provide an opportunity for intervention. Herein, we describe our alloantibody surveillance and intervention protocol that has improved graft survival. Patients (n = 69) with preoperatively positive FCXM and DSA were transplanted. Patient compatibility with donors was assessed by FCXM and donor specific antibody using single antigen bead Luminex. FCXM and DSA levels were monitored quarterly posttransplant. We identified a posttransplant profile strongly associated with chronic rejection. We then implemented a point-based formula that indicated when to initiate preemptive treatment with IVIG and plasmapheresis. The results of posttransplant antibody surveillance revealed 2 profiles. Most patients (65%) showed complete elimination of FCXM reactivity and DSA levels within 12 months of transplant. Three-year graft survival exceeded 95% and patients were chronic rejection-free. In contrast, the remaining patients failed to eliminate antibody as assessed by FCXM and DSA levels. Graft survival was inferior and chronic rejection was diagnosed in 43% of the group. Subsequent inclusion of preemptive treatment using the point-based system improved 3-year graft survival from 50% to 90%. In conclusion, the data show that implementation of an evidence based antibody surveillance protocol and an intervention protocol successfully improved graft survival.

Quantitation of alloantibody concentration can predict patient sensitivity to intravenous immunoglobulin desensitization.

Despite the success of intravenous immunoglobulin (IVIg) desensitization to reduce anti-human leukocyte antigen antibodies, its high failure rate and expense limit its usefulness. We speculated that quantitation of alloantibody concentration could allow early identification of IVIg resistant patients. Patients were described as nonresponders (n=3) or responders (n=8). Panel reactive antibodies (PRA) were determined using Flowbeads and concentration calculated as molecules of equivalent soluble fluorochrome (MESF). PRA was equivalent between nonresponders and responders before (97+/-3% vs. 76+/-20%, P=NS) and after 3 IVIg/plasmapheresis (PP) treatments but lower among responders at end-of-treatment (76+/-20% vs. 44+/-15%, P<0.01). In contrast, pretreatment MESFs were higher (333,640+/-241,352 vs. 38,741+/-5,133, P=0.006) among nonresponders than responders. During treatment, MESFs decreased (P<0.05) in 0 of 3 nonresponders vs. 8 of 8 responders. Final MESFs were higher among nonresponders than responders. We report that quantitation of MESFs allows early identification of IVIg/PP resistant patients. This sensitive and inexpensive technique should allow more effective patient selection and reduce the costs associated with desensitization.