Post-kidney transplant cancers: Racial and ethnic differences in sun-exposed skin versus non-sun-exposed anogenital skin.

BACKGROUND: Transplant recipients have a 2- to 4-fold increased risk of developing malignancies over the general population. Cancer is the second most common cause of death for recipients. The magnitude of the risk depends on the cancer type and increases in viral-related malignancies. Skin cancer is the most common. However, data in most cancer registries is limited to cutaneous melanomas, thereby limiting the epidemiologic examination of cancer risk in non-melanoma skin cancer. Our goal was to evaluate post-kidney transplant cancer cases and sites in our population to guide screening recommendations. METHODS: Between 2009 and 2015, a retrospective study of adult kidney recipients transplanted at East Carolina University was conducted. The first cancer diagnosis after transplant through February 18, 2020, was captured and analyzed. Patient demographics, cancer sites, and histological diagnoses were analyzed and compared. p16 immunohistochemistry was used as a surrogate marker for high-risk human papillomavirus (HPV) infection. RESULTS: Retrospectively, kidney transplant recipients were analyzed (N = 439), the majority were non-Hispanic Black (NHB) individuals, 312 (71.1%), and 127 (28.9%) were non-Hispanic White (NHW) individuals. Of these, 59 (13.4%) developed a posttransplant malignancy, with the majority on sun-exposed skin found in NHW. NHB had all anogenital/mucosa skin cancers on non-sun-exposed skin. Of these detected in NHB, all were squamous cell carcinomas, with five out of six (83.3%) being positive for p16. CONCLUSIONS: Posttransplant malignancy differed significantly by race, site, and potential source of etiology. The majority of malignancies are likely explained by acceleration of precursor lesions from prior exposure to ultraviolet rays or HPV.

Donor-Derived Neuroendocrine Carcinoma Transmission to Two Kidney Transplant Recipients Demonstrated by Short Tandem Repeat Analysis: A Case Report.

Cancer transmission from a donor organ to a transplant recipient is a rare but not infrequently fatal event. We report a case of lung cancer transmission from a deceased donor to 2 kidney recipients. Approximately 1 year after uneventful kidney transplantation, both recipients developed acute kidney failure. Computed tomography imaging of abdomen and pelvis for both recipients showed masses in the transplanted kidneys along with innumerable masses in the livers. Pathologic examinations for both cases demonstrated high-grade neuroendocrine carcinoma with "mirror image" histologic findings in the transplant kidneys with liver metastases. Short tandem repeat (STR) analyses were performed to determine the origin of the tumors. STRs of both tumors were nearly identical to that of the donor, proving that both tumors were from the same donor. Immunohistochemical analyses showed that both tumors were positive for thyroid transcription factor 1, supporting a lung primary. One recipient died as a direct sequela to metastatic tumor, and the other required transplant nephrectomy and chemotherapy. Awareness of this largely nonpreventable complication and prompt molecular testing if cancer transmission is suspected are important.

Impact of CYP3A5 genomic variances on clinical outcomes among African American kidney transplant recipients.

Little is known about the impact of CYP3A5 polymorphisms on transplantation outcomes among African American (AA) kidney transplant recipients (KTRs). To assess this issue, clinical outcomes were compared between AA CYP3A5*1 expressers and nonexpressers. This retrospective cohort study analyzed AA KTRs. Biopsy-proven acute rejection (BPAR), delayed graft function (DGF), glomerular filtration rate (GFR), infections, and tacrolimus dosing requirements were examined in 106 immunologically high-risk AA kidney transplant patients over a 2-year follow-up period. In CYP3A5*1 expressers compared to nonexpressers, the incidence of BPAR was significantly higher in the first 6 months (13% vs 0%; P = .016) compared to 24 months (13% vs 7%; P = .521). Tacrolimus total daily dose at first therapeutic level was significantly higher in CYP3A5*1 expressers (12 mg/day) compared to nonexpressers (8 mg/day; P < .001). Compared to CYP3A5*1 nonexpressers, DGF incidence was significantly higher among CYP3A5*1 expressers (27.6% vs 6.7%; P = .006). By contrast, median GFR was significantly higher in CYP3A5*1 expressers compared to nonexpressers (54.5 mL/min vs 50.0 mL/min; P = .003) at 24 months. The findings from this retrospective study suggest that AAs with CYP3A5*1 expression require 50% more tacrolimus and have an increased incidence of DGF and acute rejection.

Prevalence of CYP3A5 Genomic Variances and Their Impact on Tacrolimus Dosing Requirements among Kidney Transplant Recipients in Eastern North Carolina.

To assess the prevalence of CYP3A5 genomic variances and their impact on tacrolimus (TAC) dosing requirements among kidney transplant recipients in eastern North Carolina, we conducted a single-center retrospective cohort study at a large tertiary care medical center. A total of 162 adults who received a kidney transplant between March 1, 2013, and February 28, 2015, and received oral TAC as part of their maintenance immunosuppression were enrolled. Of these patients, 85 patients expressed a genotype with a CYP3A5*1 variant (CYP3A5*1 group), and 77 patients expressed genotypes with other CYP3A5 variants (nonexpressor group). All patients were followed for 1 year posttransplantation. The primary end point was the TAC total daily dose (TDD) required to achieve the first therapeutic trough level based on the presence or absence of the CYP3A5*1 variant. The prevalence of different CYP3A5 variants across race/ethnicities in the study cohort was determined by CYP3A5 genotyping for each patient. The CYP3A5*1 and nonexpressor groups did not differ significantly with respect to sex, mean age, or mean weight. The CYP3A5*1 group was largely African American (93%, p≤0.0005) compared with other race/ethnicities. Among the CYP3A5*1 expressors compared with nonexpressors, the mean TAC TDD in milligrams at the first therapeutic TAC level was significantly higher (12 vs 8 mg/day, p≤0.001). Similarly, the mean TAC TDD in milligrams/kilogram was 50% greater among CYP3A5*1 expressors (0.15 vs 0.1 mg/kg/day, p≤0.0005). The predominant genotypic variants were CYP3A5*3/*3 (33%), CYP3A5*1/*3 (20%), and CYP3A5*1/*1 (19%). This study illustrates the prevalence of the CYP3A5*1 variant among African-American kidney transplant recipients and the effect of this gene expression on the TAC TDD. Patients with the CYP3A5*1 variant require higher TAC doses, on average, to achieve desirable drug levels. In addition, this study provides transplant clinicians with insight and support to dose TAC more aggressively in African-American kidney transplant recipients who may be at higher risk for both toxicities as well as poor clinical outcomes related to inadequate immunosuppression.

Racial differences in incident de novo donor-specific anti-HLA antibody among primary renal allograft recipients: results from a single center cohort study.

Controversy exists as to whether African American (AA) transplant recipients are at risk for developing de novo donor-specific anti-human leucocyte antigen (HLA) antibody (dnDSA). We studied 341 HLA-mismatched, primary renal allograft recipients who were consecutively transplanted between 3/1999 and 12/2010. Sera were collected sequentially pre- and post-transplant and tested for anti-HLA immunoglobulin G (IgG) via single antigen bead assay. Of the 341 transplant patients (225 AA and 116 non-AA), 107 developed dnDSA at a median of 9.2 months post-transplant. AA patients had a 5-year dnDSA incidence of 35%. This was significantly higher than the 5-year dnDSA incidence for non-AA patients (21%). DQ mismatch (risk) and receiving a living-related donor (LRD) transplant (protective) were transplant factors associated with dnDSA. Within the AA patient cohort, HLA-DQ mismatch, not-receiving a LRD transplant, nonadherence and BK viraemia were the most common factors associated with early dnDSA (occurring <24 months post-transplant). Nonadherence and pretransplant diabetes history were the strong precursors to late dnDSA. Despite the higher rates of dnDSA in the AA cohort, post-dnDSA survival was the same in AA and non-AA patients. This study suggests that DQ matching, increasing LRD transplantation in AA patients and minimizing under-immunosuppression will be key to preventing dnDSA.

Incidence and impact of anti-HLA-DP antibodies in renal transplantation.

BACKGROUND: The role of anti-HLA-DP antibodies in renal transplantation is poorly defined. This study describes the impact of donor (donor-specific antibody [DSA]) and non-donor-specific antibodies against HLA-DP antigens in renal transplant patients. METHODS: Of 195 consecutive patients transplanted between September 2009 and December 2011, 166 primary kidney recipients and their donors were typed (high-resolution) for DP antigens. Sera taken pre-transplant and at 1, 3, 6, 9, and 12 months, and annually post-transplant were retrospectively tested for anti-DP antibodies using single-antigen beads. RESULTS: In 81 (49%) patients, anti-DP antibodies were found; 64% (n=52) of patients were positive in the pre-transplant samples and 36% (n=29) were positive exclusively post-transplant. The median time from transplantation to antibody was 20.9 months. Fifty-five percent (n=16) of the de novo anti-DP antibodies were accompanied by another de novo DSA. Anti-DP antibody-positive patients had a higher rate of rejection (compared with anti-DP antibody-negative patients, P=.01). The estimated glomerular filtration rate declined more with anti-DP antibodies (-5.5% vs +26%). CONCLUSIONS: Antibodies against HLA-DP antigens are common. De novo anti-DP antibodies commonly appear after acute rejection and accompany DSA, which makes it difficult to determine whether anti-DP antibodies are the cause or the consequence of graft injury.

Risk Stratification of Human Leukocyte Antigen Class II Donor Specific Antibody Positive Patients by Immunoglobulin G Subclasses.

BACKGROUND: Human leukocyte antigen (HLA) antibodies are a major cause of graft loss in mismatched transplant recipients. However, the time to graft loss resulting from antibody induced injury is unpredictable. The unpredictable nature of antibodies may be related to the subclass of antibodies. In this study, HLA immunoglobulin G (IgG) subclasses were investigated to determine whether a unique IgG subclass composition could better identify those patients at eminent risk for graft loss. METHODS: The serial serum samples from the 57 patients with post-transplant HLA class II donor specific antibodies (DSA) were tested for the three IgG subclasses (IgG1, IgG3, and IgG4). RESULTS: IgG3 and IgG4 were highly prevalent in failed patients compared to functioning patients (82 % vs. 34%, 45% vs. 20%, respectively). IgG3 development showed a distinct subclass trend between failed and functioning patients with poor graft survival (log rank p=0.0006). IgG1 was almost equally abundant in both groups (100% and 97%, respectively). Of the 5 patterns of IgG subclass combinations observed, IgG1+3+ showed the strongest association with graft failure (hazard ratio 3.14, p=0.007). CONCLUSION: Patients with IgG3 subclass HLA DSA showed lower graft survival. Post-transplant monitoring for IgG subclasses rather than total IgG monitoring may identify patients at risk for graft failure.

Changes in successive measures of de novo donor-specific anti-human leukocyte antigen antibodies intensity and the development of allograft dysfunction.

BACKGROUND: Many patients develop de novo donor-specific anti-human leukocyte antigen antibodies (dnDSA) after transplantation. Despite development of dnDSA, not all patients will immediately fail. This study analyzes dnDSA intensity and longitudinal trends as prospective clinical parameters to assess subsequent allograft function. METHODS: Twenty-four patients with dnDSA onset in the first 2 years after transplantation received antibody monitoring by LABScreen single antigen beads. Estimated glomerular filtration rate (eGFR) was recorded at time of dnDSA onset and up to 24 months thereafter. The dnDSA mean fluorescence intensity (MFI) of the stable function patient group (n=8; eGFR decline ≤ 25%) was compared with the impaired function patient group (n=16; eGFR decline>25%) using first year peak MFI (pMFI), eight month MFI change (ΔMFI), and eighteen month MFI trend (MFI slope). RESULTS: Both groups showed similar dnDSA characteristics (time to onset after transplantation, class I/II distribution, and initial MFI). Between groups, MFI trends were analyzed. Impaired patients showed a higher pMFI during the first year (median pMFI, 13,055 vs. 2,397; P=0.007). Longitudinal analysis revealed that ΔMFI was strongly associated with dysfunction. Both a ΔMFI increase greater than 20% as well as a stronger increase (ΔMFI>50%) were followed by graft dysfunction in almost all patients and could significantly differentiate between stable and impaired function patients (P=0.001 and P=0.04, respectively). CONCLUSION: Our study suggests that tracking dnDSA intensity, particularly in the early period after onset, is important to estimate the impact of dnDSA on the allograft and could, therefore, determine help on how best to monitor patients with dnDSA.

Impact of IgM and IgG3 anti-HLA alloantibodies in primary renal allograft recipients.

BACKGROUND: With standard IgG donor-specific anti-HLA antibody (DSA) testing, it is unclear which immunoglobulin-G (IgG) DSA positive patients will fail. We looked further into the immune response by studying immunoglobulin-M (IgM) and IgG subclass 3 (IgG3) DSA to determine if these identify the IgG DSA patients at highest risk for allograft loss. METHODS: In 189 consecutively transplanted primary renal allograft recipients, sera were collected sequentially pre- and posttransplant. Of the 189, 179 patients had sera available to retrospectively test for anti-HLA IgG, IgM, and IgG3 antibodies via LABScreen single-antigen bead assay and were included in the study. All patients had a negative crossmatch. Per patient, all DSA (IgM, IgG3, and IgG) refers to the same serologic specificity. RESULTS: Overall, 100 (56%) patients developed an alloimmune response (IgM or IgG DSA positive, or both). Ninety-five patients developed IgM DSA and 47 patients developed IgG DSA. IgM DSA was detected in 42 of 47 patients with IgG DSA. IgM DSA alone did not increase the allograft loss risk, whereas IgG DSA did (P=0.002). Once IgG DSA appeared, IgM DSA persisted in 33 patients and an isotype switch to IgG3 positive DSA occurred in 25 patients. Patients with IgM persistent IgG3 positive DSA (n=19) were more likely to have allograft failure than those without (P=0.02). CONCLUSION: This study shows the evolution of the humoral immune response from IgM to IgG DSA posttransplant. We found that development of IgM persistent IgG3 positive DSA identifies the most dangerous IgG DSA subpopulation.

Improved Long-Term Survival in Kidney Transplant Recipients with Donor-Specific HLA Antibodies After Mycophenolic Acid Escalation.

The development of donor specific antibodies (DSA) post transplant has been associated with chronic rejection and graft failure. In a longitudinal study, we have shown that increases in DSA precede rejection by months, thus allowing time for intervention. We hypothesized that mycophenolic acid (MPA) dose increases may reduce and/or stabilize DSA strength and also preserve renal function. Thirty stable DSA positive kidney transplant recipients participated in this Institutional Review Board approved, exploratory, open-label, single center study to assess the efficacy of MPA dose escalation in patients with DSA. MPA escalation was well tolerated and most patients were able to take higher doses for at least two years (duration of the study). In addition, MPA escalation is safe and participants had no significant side effects such as cytomegalovirus and BK infections. Long-term allograft survival of the MPA escalation group was superior when compared with the control group (p = 0.018). This pilot study indicates that escalation of MPA is safe and may stabilize DSA. In addition, five-year follow up demonstrates improved long-term survival with MPA escalation compared with DSA positive recipients receiving the standard of care. Additional studies using larger cohorts are warranted.

Trends and characteristics in early glomerular filtration rate decline after posttransplantation alloantibody appearance.

BACKGROUND: Approximately 7% to 9% of patients with donor-specific anti-human leukocyte antigen (HLA) antibodies (DSA) fail within 1 year post-DSA onset. However, little is known as to how this DSA-associated failure temporally progresses. This longitudinal study investigates DSA's temporal relationship to allograft dysfunction and identifies predictors of allograft function's progressive deterioration post-DSA. METHODS: A cohort of 175 non-HLA identical patients receiving their first transplant between March 1999 and March 2006 were analyzed. Protocol testing for DSA via single antigen beads was done before transplantation and at 1, 3, 6, 9, and 12 months after transplantation then annually. Estimated glomerular filtration rate (eGFR) was analyzed before and after DSA onset. RESULTS: Forty-two patients developed DSA and had adequate eGFR information for analysis. Before DSA onset, the 42 patients had stable eGFR. By 1 year post-DSA, the cohort's eGFR was significantly lower (P<0.001); however, 30 of 42 had stable function. Twelve patients had failure or early allograft dysfunction (eGFR decline >25% from DSA onset). Those who failed early (by 1 year post-DSA) had more antibody-mediated rejection than stable patients (P=0.03). Late failures (after 1 year post-DSA) were predictable with evidence of early allograft dysfunction (eGFR decline >25% by 1 year post-DSA; P<0.001). Early allograft dysfunction preceded late failure by nearly 1 year. CONCLUSIONS: DSA is temporally related to allograft function deterioration. However, in many cases, late allograft failures are preceded by early allograft dysfunction. Therefore, monitoring for early allograft dysfunction provides treating physicians with a window of opportunity for treatment or continued monitoring.

The role of immunoglobulin-G subclasses and C1q in de novo HLA-DQ donor-specific antibody kidney transplantation outcomes.

BACKGROUND: Anti-HLA-DQ antibodies are the predominant HLA class II donor-specific antibodies (DSAs) after transplantation. Recently, de novo DQ DSA has been associated with worse allograft outcomes. The aim of this study was to determine the further complement-binding characteristics of the most harmful DQ DSA. METHODS: Single-antigen bead technology was used to screen 284 primary kidney transplant recipients for the presence of posttransplantation DQ DSA. Peak DSA sera of 34 recipients with only de novo DQ DSA and of 20 recipients with de novo DQ plus other DSAs were further analyzed by a modified single-antigen bead assay using immunoglobulin (Ig)-G subclass-specific reporter antibodies and a C1q-binding assay. RESULTS: Compared with recipients who did not have DSA, those with de novo persistent DQ-only DSA and with de novo DQ plus other DSAs had more acute rejection (AR) episodes (22%, P=0.005; and 36%, P=0.0009), increased risk of allograft loss (hazards ratio, 3.7, P=0.03; and hazards ratio, 11.4, P=0.001), and a lower 5-year allograft survival. De novo DQ-only recipients with AR had more IgG1/IgG3 combination and C1q-binding antibodies (51%, P=0.01; and 63%, P=0.001) than patients with no AR. Furthermore, the presence of C1q-binding de novo DQ DSA was associated with a 30% lower 5-year allograft survival (P=0.003). CONCLUSIONS: The presence of de novo persistent, complement-binding DQ DSA negatively impacts kidney allograft outcomes. Therefore, early posttransplantation detection, monitoring, and removal of complement-binding DQ might be crucial for improving long-term kidney transplantation outcomes.

Incidence and impact of de novo donor-specific alloantibody in primary renal allografts.

BACKGROUND: To date, limited information is available describing the incidence and impact of de novo donor-specific anti-human leukocyte antigen (HLA) antibodies (dnDSA) in the primary renal transplant patient. This report details the dnDSA incidence and actual 3-year post-dnDSA graft outcomes. METHODS: The study includes 189 consecutive nonsensitized, non-HLA-identical patients who received a primary kidney transplant between March 1999 and March 2006. Protocol testing for DSA via LABScreen single antigen beads (One Lambda) was done before transplantation and at 1, 3, 6, 9, and 12 months after transplantation then annually and when clinically indicated. RESULTS: Of 189 patients, 47 (25%) developed dnDSA within 10 years. The 5-year posttransplantation cumulative incidence was 20%, with the largest proportion of patients developing dnDSA in the first posttransplantation year (11%). Young patients (18-35 years old at transplantation), deceased-donor transplant recipients, pretransplantation HLA (non-DSA)-positive patients, and patients with a DQ mismatch were the most likely to develop dnDSA. From DSA appearance, 9% of patients lost their graft at 1 year. Actual 3-year death-censored post-dnDSA graft loss was 24%. CONCLUSION: We conclude that 11% of the patients without detectable DSA at transplantation will have detectable DSA at 1 year, and over the next 4 years, the incidence of dnDSA will increase to 20%. After dnDSA development, 24% of the patients will fail within 3 years. Given these findings, future trials are warranted to determine if treatment of dnDSA-positive patients can prevent allograft failure.

Novel biomarker combination predicts long-term allograft outcome.

Donor specific human leukocyte antigen (HLA) antibodies (DSA) are a significant cause of allograft failure. However, it has been reported that some DSA negative patients still experience allograft failure. In addition, some DSA positive patients maintain good graft function for >20 years. These findings suggest that while DSA is a cause of failure, it is not the sole risk factor for graft dysfunction and that the presence of DSA alone may not predict the time course of graft failure. Here, we report the predictive value of a proprietary panel of four biomarkers in long-term renal allograft outcome. A total of 310 consecutive patients, who received kidney transplants between 1999 and 2012, were included in this study. Recipient sera was tested for HLA antibodies and biomarkers at 3, 6, 12, 24, and 36 months post-transplant. HLA antibodies were identified using Labscreen single antigen beads. The biomarker combination (BMC) test consisted of a proprietary panel of 4 biomarkers and was performed using Luminex. Sera were defined as positive when any one of the 4 biomarkers became detectable. Sera of normal healthy people were used as negative controls. Graft survival analyses were performed and compared between different patient groups based on the positivity of DSA and BMC. Our results indicate that 57% of DSA negative patients and 54% of DSA positive patients had detectable biomarkers. There was no significant difference in BMC positive patients between the DSA positive and negative groups, which suggests that presence of BMC is not associated with HLA DSA. DSA positive patients had a 10% lower 10-year graft survival rate than patients without DSA, while BMC positive patients had a 25% lower 10-year graft survival rate than patients without detectable BMC. When DSA negative patients were divided into two groups based on the positivity of BMC, BMC positive patients had a 20% lower 10-year graft survival rate compared to BMC negative patients (p<0.05). Similarly, when DSA positive patients were divided into two groups based on the positivity of BMC, BMC positive patients had a 30% lower 10-year graft survival rate compared to BMC negative patients (p<0.01). When both DSA and BMC testing results were considered, DSA and BMC double positive patients had the lowest and double negative patients had the highest graft survival rates. The survival rates for the BMC alone and DSA alone positive groups were in between (p<0.001). Multivariate Cox models confirmed that BMC was an independent risk factor for graft failure, with a higher hazard ratio than DSA (BMC=2.60 versus DSA=1.64). In conclusion, serum BMC is an independent predictor of graft failure. BMC was more significantly associated with graft failure than DSA. In combination with DSA, BMC better predicted graft outcome than DSA or BMC alone.

A report of the epidemiology of de novo donor-specific anti-HLA antibodies (DSA) in "low-risk" renal transplant recipients.

The donor specific anti-HLA antibody (DSA) has been increasingly recognized as the major cause of allograft loss. Despite this, no published reports exist describing the true epidemiology of de novo DSA.Here we describe the epidemiology of DSA based on the results of one of the longest running antibody study in consecutive renal transplant recipients. The study includes 224 non-sensitized, non-HLA-identical patients who received a primary kidney transplant between 3/1999-3/2006. Protocol testing for DSA was done pre-transplant, at 1, 3, 6, 9, and 12 months, and then annually. DSA was tested using single antigen beads. Data from the East Carolina University transplant cohort indicate that the prevalence of DSA in the first year post-transplant is 12.1 cases per 100. The average annual incidence of DSA is 4.7 per 100 cases, per year. The highest incidence of DSA was in the first year post transplant. Although deceased donors and African-Americans have a higher incidence rate of DSA than the comparator living donors and non-African American groups, respectively, these factors were not associated with DSA onset. The one factor found to be predictive of DSA was DQ mismatch (p = 0.036). Based on these epidemiologic findings in combination with previous reports showing DSA is a cause of allograft failure, it seems reasonable that at least annual testing should be done even in "low-risk" transplant patients, because every year a new 5% of patients will develop DSA.

Beyond histology: lowering human leukocyte antigen antibody to improve renal allograft survival in acute rejection.

BACKGROUND: The common endpoint in the treatment of antibody-mediated rejection (AMR) is functional reversal (creatinine levels). Reduction of human leukocyte antigen (HLA) antibody strength is not commonly considered as an essential endpoint for AMR resolution. The purpose of this study was to determine whether reduction in HLA antibody intensity in patients with histologic AMR reversal influences long-term renal allograft survival. METHODS: Renal allograft recipients were included if he or she had a biopsy diagnosis of AMR (between August 2000 and October 2008) and serial evaluation for HLA antibodies prebiopsy and postbiopsy. Antibody reduction was defined as mean fluorescence intensity decrease more than 50% in highest intensity antibody after AMR therapy and the absence of new antibody formation. Patients were treated with plasmapheresis, thymoglobulin/OKT3, and corticosteroids. Survival analysis was performed using STATA/MP v10 (College Station, TX). RESULTS: Twenty-eight patients were analyzed. Antibody reduction failed to occur in 22 of 28 cases. Baseline characteristics were similar between groups. Antibody nonresponders had significantly shorter allograft survival time (61.4 months) compared with antibody responders (no failures) (P=0.04, log-rank test). CONCLUSIONS: In conclusion, failure to significantly reduce antibody levels and prevent new formation was strongly predictive of allograft loss. This observation suggests that the therapeutic intervention that reduces antibody production may prolong graft survival in transplantation.

Organ procurement and transplantation network/united network for organ sharing histocompatibility committee collaborative study to evaluate prediction of crossmatch results in highly sensitized patients.

BACKGROUND: The requirement for a prospective crossmatch limits some organ allocation to local areas. The delay necessitated by the crossmatch restricts the distance across which offers can be made without unduly increasing the ischemia time. A collaborative study involving 14 transplant centers was undertaken by the Organ Procurement and Transplantation Network/United Network for Organ Sharing (OPTN/UNOS) Histocompatibility Committee to evaluate the accuracy with which the detection of unacceptable human leukocyte antigen (HLA) antigens by most advanced solid phase immunoassays can predict crossmatch results. In addition, using actual patients' unacceptable HLA antigens, the number of compatible donors that would have been available from the OPTN deceased kidney donors during 2002 to 2004 were investigated. METHODS: Panel reactive antibodies were performed by conventional or solid phase assays, and crossmatches were performed by cytotoxicity or flow cytometry. Analyses were stratified for T and B cell and by method of identifying unacceptable HLA antigens and crossmatch techniques. RESULTS: Combination of solid phase immunoassays and flow cytometry crossmatches resulted in a higher prediction rates of positive T cell (86.1%-93.5%) and B-cell crossmatches (91%-97.8%). Prediction of negative crossmatches based on different combination of panel reactive antibodies and crossmatch techniques varied from 14.3% to 57.1%. Furthermore, numerous potential compatible donors were identified for each patient, regardless of their ethnicity, in the OPTN database, when predicted incompatible ones were excluded. CONCLUSIONS: The above results showed that with the advent of solid phase immunoassays, HLA antibodies can now be accurately detected resulting in prediction of crossmatch outcome. This should facilitate organ allocation and prevents shipment of organs to distant incompatible recipients.

Delayed skin allograft rejection following matrix membrane pretreatment.

INTRODUCTION: No solution has been offered to induce long-term skin allograft survival in burn patients. We investigated whether transplant acceptance could be improved by a nonsystemic pretreatment of the graft and recipient wound surfaces with a bioengineered interface consisting of an acellular matrix membrane. METHODS: Group 1 (n=30): Crosstransplants of untreated skin grafts between BALB/c and C57BL/6 mice. Group 2 (n=30): Crosstransplants of matrix-treated skin grafts between BALB/c and C57BL/6 mice. Group 3 (n=30): Retransplantation of skin grafts from the original donor on to the sensitised recipients. Sensitisation was accomplished by prior transplantation of an untreated skin allograft from the same donor (Group 1 mice). Two skin grafts were transplanted: one treated and one untreated. RESULTS: Rejection occurred in the untreated group after a mean of 6.8 days (+/-1.5 days). In contrast, treatment with the bioengineered matrix membrane was found to substantially prolong allograft survival with a mean of 28 days (+/-3.8 days). Graft survival between the two groups reached statistical significance (P<0.05). In the sensitised mice, the untreated skin regrafts were all rejected in an accelerated fashion with an onset of less than 4 days (mean+/-1 days). However, the matrix membrane-treated skin regrafts were maintained for a mean of 18 days (+/-3 days). CONCLUSION: These results show that treatment with the bioengineered matrix membrane greatly delays the onset of acute allograft rejection. The described topical application to the wound surfaces of both the graft and the recipient may offer a new and readily available source of wound coverage in patients with extensive burns.

Analysis of HLA class I specific antibodies in patients with failed allografts.

BACKGROUND: The goals of this study are first to determine the epitope specificity of donor specific antibody (DSA) in the serum of alloimmunized transplant patients with a failed renal graft; and second to understand the correlation between the development of DSA and nondonor specific antibody (NDSA). METHODS: The sera of 35 pretransplant panel reactive antibody (PRA)-negative patients with failed allografts were examined with single-antigen (SA) luminex beads to identify human leukocyte antigen (HLA)-A and -B antibodies. Potential HLA antibody epitopes were identified by using computer software and verified by absorption and elution from single-antigen cell lines. RESULTS: Twenty-seven patients developed donor-specific HLA-A and/or -B antibodies, while the remaining eight patients had only nondonor-specific HLA-A and/or -B antibodies. The DSA-positive patients also had a long list of NDSA. Sixty-eight percent of the reactions found in 27 recipients with DSA were attributable to 66 epitopes on the mismatched donor HLA molecule. All 39 NDSA in eight patients with only NDSA shared 17 epitopes within positive allele specificities. By absorption and elution using recombinant cell lines having a single HLA specificity, we confirmed the epitopes involved in three patients. CONCLUSION: Development of most NDSA in patients with failed allografts is likely due to sharing epitopes with DSA and/or other NDSA.

Clinical and anti-HLA antibody profile of nine renal transplant recipients with failed grafts: donor-specific and non-donor-specific antibody development.

This study applied the single antigen microsphere technology to the retrospective analysis of sequential post-transplant serum samples in the context of the patient's clinical course. Detailed information on nine of the study patients was presented as representative of the larger cohort and illustrative of different patterns of anti-HLA antibody development and different clinical scenarios that culminated in graft failure. Our major observations are summarized as follows: 1. These data confirm the high sensitivity of the single antigen bead method: In some patients, DSA and NDSA that were undetected by standard methods were found pre-transplant and in sequential post-transplant samples. 2. The precise role that anti-HLA antibody plays in a particular rejection are complicated in cases in which humoral rejection is not diagnosed in the biopsy: The possible involvement of ADCC and mechanisms involving an indirect role for antibody in the rejection process should be carefully investigated. 3. Although anti-HLA antibodies are associated with graft rejection, the time interval between detection and rejection can vary dramatically between patients. Both DSA and NDSA can be adsorbed by the graft and erratically detected in the circulation, in some cases remaining undetected until nephrectomy. 4. Anti-HLA antibody strengths often fluctuate widely over a patient's clinical course, with de novo DSA generally of greater strength than de novo NDSA. 5. In addition to DSA, we have observed the consistent induction of diverse, cross-reactive NDSA. This occurs not only during the post-transplant course but also after graft failure, when immunosuppression is tapered prior to nephrectomy. Our data support further studies to evaluate the value of prospective monitoring of anti-HLA antibodies to better understand the place of anti-HLA antibodies in acute rejection. This may improve our ability to reverse some acute rejection episodes. Since acute rejection has been considered a predictor of late graft loss via chronic allograft nephropathy, understanding and modifying the antibody response is critical to extending the longevity of transplanted organs. Finally, since the strong sensitization to NDSA will seriously hamper the ability to identify a compatible donor for a future transplant, these data reinforce the importance of minimizing HLA mismatches between the donor and the recipient.