HLA gene dosage effect on renal allograft survival

The impact of pretransplant suspected HLA antibody on the long-term outcome of the graft kidney: A retrospective cohort study

INTRODUCTION

The preoperative examination of kidney transplantation includes HLA antibody screening to initially determine the presence of preexisting donor-specific antibody (DSA) that mediates hyperacute rejection. Recipients with positive HLA antibodies require further HLA specificity analysis to type the antigen and determine the antigen mismatches between the donor and recipient. However, recipients with suspected antibodies would have no further HLA specificity analysis. It is unclear whether suspected HLA antibodies would affect renal graft function. This study aimed to explore the impact of pretransplant suspected HLA antibody on the long-term outcome of the graft kidney and thus determine the necessity of routinely performing the HLA specificity analysis in recipients with suspected HLA antibodies preoperatively.

METHODS

This is a single-center retrospective cohort study. 179 kidney transplant recipients (KTRs) were included and further divided into HLA antibody-negative group (Group 1) and HLA antibody-suspected groups (Group 2) based on the result of the pretransplant HLA antibody screen test. And the antibody-suspected group was further divided into a low-mismatched group (Group A) and a high-mismatched group (Group B) according to the HLA specificity analysis. We tracked the renal function indexes, biochemical indexes, and posttransplant adverse events within 5 years after transplantation and explored the necessity of further HLA specificity analysis in recipients with pretransplant suspected HLA antibodies.

RESULTS

There was no statistically significant difference in demographics between HLA antibody-negative group and HLA antibody-suspected groups. At 5 years of follow-up, the KTRs in HLA antibody-negative group had significantly higher eGFR levels, lower serum creatinine levels, and less urinary protein compared to those in antibody-suspected group. Meanwhile, the KTRs in low-mismatched group also had significantly higher eGFR levels, lower serum creatinine levels, and less proteinuria compared to those in high-mismatched group. Correlation analysis showed that the age of KTRs, urinary protein levels and the load capacity of HLA mismatches were associated with eGFR levels of KTRs at 5 year posttransplant.

CONCLUSION

KTRs with suspected HLA antibodies before kidney transplantation have worse graft function than the preoperative HLA antibody-negative recipients in the long-term posttransplant follow-up. The specific load capacity of HLA mismatches, the age of the recipient and the urinary protein was found to be negatively correlated with long-term posttransplant renal outcomes. It is necessary to undergo further HLA specificity analysis for recipients with suspected HLA antibodies in HLA antibody screen test to explicit HLA mismatches and improve long-term posttransplant outcomes.

Seeking Standardized Definitions for HLA-incompatible Kidney Transplants: A Systematic Review

BACKGROUND

There is no standard definition for "HLA incompatible" transplants. For the first time, we systematically assessed how HLA incompatibility was defined in contemporary peer-reviewed publications and its prognostic implication to transplant outcomes.

METHODS

We combined 2 independent searches of MEDLINE, EMBASE, and the Cochrane Library from 2015 to 2019. Content-expert reviewers screened for original research on outcomes of HLA-incompatible transplants (defined as allele or molecular mismatch and solid-phase or cell-based assays). We ascertained the completeness of reporting on a predefined set of variables assessing HLA incompatibility, therapies, and outcomes. Given significant heterogeneity, we conducted narrative synthesis and assessed risk of bias in studies examining the association between death-censored graft failure and HLA incompatibility.

RESULTS

Of 6656 screened articles, 163 evaluated transplant outcomes by HLA incompatibility. Most articles reported on cytotoxic/flow T-cell crossmatches (n = 98). Molecular genotypes were reported for selected loci at the allele-group level. Sixteen articles reported on epitope compatibility. Pretransplant donor-specific HLA antibodies were often considered (n = 143); yet there was heterogeneity in sample handling, assay procedure, and incomplete reporting on donor-specific HLA antibodies assignment. Induction (n = 129) and maintenance immunosuppression (n = 140) were frequently mentioned but less so rejection treatment (n = 72) and desensitization (n = 70). Studies assessing death-censored graft failure risk by HLA incompatibility were vulnerable to bias in the participant, predictor, and analysis domains.

CONCLUSIONS

Optimization of transplant outcomes and personalized care depends on accurate HLA compatibility assessment. Reporting on a standard set of variables will help assess generalizability of research, allow knowledge synthesis, and facilitate international collaboration in clinical trials.

Clinical Outcomes in Pediatric Renal Transplant Recipients Who Received Steroid-Based Immunosuppressive Regimen

BACKGROUND

Although the clinical outcomes of pediatric renal transplantation (RT) in developed countries have improved significantly, the data on clinical outcomes in developing countries are wildly different.

METHODS

Children and adolescents who had undergone RT at Ramathibodi Hospital between March 2001 and August 2014 were included.

RESULTS

Patients were divided into 2 groups: living related donor (LRD) group (n = 13) and deceased donor (DD) group (n = 30). Prolonged cold ischemic time over 13 hours was significantly associated with delayed graft function (P = .029). The prevalence of infection was 90.7%, in which urinary tract infection (UTI) was the most common infection. Although almost none of the patients in the LRD group received induction therapy, the prevalence of rejection was not significantly different between the 2 groups (P = .817). The comparison of graft survivals between LRD and DD groups were 100% vs 100%, 92.3% vs 100%, and 85.7% vs 81.8% at 1, 3, and 5 years, respectively (P = .938). Recurrent UTI and cytomegalovirus (CMV) infection had a negative effect on graft function at 1-year follow-up (P < .05). Rejections, bladder dysfunction, and donors aged ≥50 years were associated with graft deterioration at 3 years after RT (P < .01). None of these patients died with functioning graft.

CONCLUSION

This study demonstrated good graft and patient survival in Thai pediatric RT recipients. Although recurrent UTI and CMV infection were related to graft dysfunction at 1-year follow-up, infections had no effect on graft and patient survival in long-term follow-up.

HLA Mismatching Strategies for Solid Organ Transplantation - A Balancing Act

HLA matching provides numerous benefits in organ transplantation including better graft function, fewer rejection episodes, longer graft survival, and the possibility of reduced immunosuppression. Mismatches are attended by more frequent rejection episodes that require increased immunosuppression that, in turn, can increase the risk of infection and malignancy. HLA mismatches also incur the risk of sensitization, which can reduce the opportunity and increase waiting time for a subsequent transplant. However, other factors such as donor age, donor type, and immunosuppression protocol, can affect the benefit derived from matching. Furthermore, finding a well-matched donor may not be possible for all patients and usually prolongs waiting time. Strategies to optimize transplantation for patients without a well-matched donor should take into account the immunologic barrier represented by different mismatches: what are the least immunogenic mismatches considering the patient’s HLA phenotype; should repeated mismatches be avoided; is the patient sensitized to HLA and, if so, what are the strengths of the patient’s antibodies? This information can then be used to define the HLA type of an immunologically optimal donor and the probability of such a donor occurring. A probability that is considered to be too low may require expanding the donor population through paired donation or modifying what is acceptable, which may require employing treatment to overcome immunologic barriers such as increased immunosuppression or desensitization. Thus, transplantation must strike a balance between the risk associated with waiting for the optimal donor and the risk associated with a less than optimal donor.