Poor kidney allograft survival associated with positive B cell - Only flow cytometry cross matches: a ten year single center study

Antibodies to cryptic epitopes on HLA class I and class II heavy chains bound to single antigen beads: Clinically relevant?

Cell surface HLA class I consists of trimers, i.e., alpha - heavy chain, beta - 2 - microglobulin, and a peptide, termed closed conformers (CC) on non-activated lymphocytes. HLA class I and class II may also exist, respectively, as alpha-chain only or alpha and beta - chain only on activated cells termed open conformers (OC). We extend previous studies using an OC-specific monoclonal antibody that demonstrate LABScreen HLA class I and II single antigen beads (SABs) contain a mixture of open and closed conformers. LIFECODES SABs have bound CC only. More HLA class I and class II LABScreen SABs were reactive than LIFECODES SABs due to the presence of OC on LABScreen SABs. We hypothesized that antibody against OC on HLA B antigens would not be detected in cell based cross matches (XMs) with typical lymphocyte targets since anti-HLA OC antibodies would not react with native HLA CC on the cell surface. To test this hypothesis, we performed flow cytometry XM (FCXM) assays with sera of sufficient strength that most laboratories would likely predict positive FCXMs. Sera that reacted strongly with LABScreen SABs (>13,000 MFI) but weakly or not at all with LIFECODES SABs (<1000 MFI) gave negative T and B cell FCXMs. In contrast, sera that reacted with LIFECODES SABs (>13,000 MFI) but weakly with LABScreen SABs (<2100 MFI) exhibited positive FCXMs. Detection of antibodies directed against OC in SAB assays, may lead to inappropriate listing of unacceptable antigens, a decision not to XM or pre-or post - transplant desensitization procedures.

HLA B53 is associated with a poor outcome in black COVID-19 patients

A disproportionate incidence of death has occurred in African Americans (Blacks) in the United States due to COVID-19. The reason for this disparity is likely to be multi-factorial and may involve genetic predisposition. The association of human leukocyte antigens (HLA) with severe COVID-19 was examined in a hospitalized population (89% Black, n = 36) and compared to HLA typed non-hospitalized individuals (20% Black, n = 40) who had recovered from mild disease. For additional comparison, HLA typing data was available from kidney transplant recipients and deceased donors. Hospitalized patients were followed for 45 days after admission to our medical center with death as the primary end-point. One HLA allele, B53, appeared to be more prevalent in the hospitalized COVID-19 patients (percent of positive subjects, 30.5) compared to national data in US Black populations (percent of positive subjects, 24.5). The percent B53 positive in non-hospitalized COVID-19 patients was 2.6, significantly less than the percent positive in the hospitalized COVID-19 patients (p = 0.001, Fisher’s exact test) and less than the 8 percent positive listed in national data bases for US Caucasian populations. Significantly greater deaths (73 percent) were observed in HLA B53 positive hospitalized COVID-19 patients compared to hospitalized COVID-19 patients who were B53 negative (40 percent). Multi-variate analysis indicated that HLA B53 positive Black hospitalized COVID-19 patients were at a 7.4 fold greater risk of death than Black COVID-19 patients who were B53 negative. Consideration for accelerated vaccination and treatment should be given to HLA B53 positive Black COVID19 patients.

Phasing out the pre-transplant cytotoxicity crossmatch: Are we missing something?

Introduction:

The anti-human globulin-enhanced complement-dependent cytotoxicity crossmatch (AHG-CDCXM) assay has been used to assess the presence of donor-specific antibodies (DSA) in recipient’s serum before kidney transplantation. The flow cytometric crossmatch (FCXM) assay was first introduced as an additional test. The aim of this study was to clinically validate the single use of the FCXM assay.

Methods:

This study compared the outcomes of a cohort of kidney transplant patients that underwent FCXM only (FCXM group) versus a cohort of kidney transplant patients that underwent AHG-CDCXM (control group).

Results:

Ninety-seven patients in the FCXM group and 98 controls were included. All crossmatches in the control group were negative. One patient in the FCXM group had a positive B cell crossmatch. One year after transplantation, there were no significant differences in patient survival (p = 0.591) and graft survival (p = 0.692) between the groups. Also, no significant difference was found in the incidence of Banff ≥ 1A acute cellular rejection episodes (p = 0.289). However, acute antibody-mediated rejections occurred in 3 controls (p = 0.028).

Conclusion:

The results showed that discontinuing the AHG-CDCXM assay does not modify the clinical outcomes in a 1-year follow-up.

DEĞER M, KÖPRÜ B, DERİCİ Ü, ARINSOY T. High neutrophil to lymphocyte ratio predicts acute allograft rejection in kidney transplantation; a retrospective study

Background/aim

Our research focused on the identification of easily available and sensitive markers for early prediction of acute kidney allograft rejection (AR). We aimed to investigate the association between neutrophil-to-lymphocyte ratio (NLR) and AR in kidney transplant patients.

Materials and methods

The medical records of 51 kidney transplant patients [12 female/39 male; median age of 32 (IQR: 24–44) years] were evaluated retrospectively. We considered a cut-off value of >2.5 as high NLR.

Results

A total of 22 biopsy-proven AR patients and 29 controls were evaluated. The AR group had a higher NLR compared to the controls (P < 0.001). NLR levels over 2.5 [95% CI: 54.88 (9.96–302.3), P < 0.001] were significantly associated with AR in univariate analysis. The NLR levels were the only significant factor associated with AR in multivariate models, in model 1 (adjusted by age and sex) [95% CI: 114 (11.1–1175), P < 0.001], and in model 2 (adjusted by steroid dosage, uric acid, and NLR) [95% CI: 4.60 (1.59–29.3), P = 0.004].

Conclusions

Our data showed that higher NLR values (>2.5) are associated with AR in kidney transplant patients, leading to the conclusion that NLR might be an easily available and useful marker option for detection of AR in this patient population.

Preformed Donor-specific Antibodies Against HLA Class II and Graft Outcomes in Deceased-donor Kidney Transplantation

Background

Many kidney transplant centers in the United States report both HLA class I and II antibodies detected by sensitive solid-phase assays (SPAs) to United Network for Organ Sharing as unacceptable antigens, significantly reducing the compatible donor organ pool and prolonging waiting time for highly sensitized patients. However, the clinical relevance of all detected donor-specific antibodies (DSAs) by SPA is not unequivocal, because fluorescence intensity does not always accurately reflect antibody pathogenicity. Our center does not exclude patients from transplantation based on DSA class II.

Methods

We performed a retrospective analysis in 179 deceased-donor kidney transplant recipients with solely DSA class II before transplant and patients without DSA and compared graft survival, rejection, and clinical outcomes. Patient survival was also compared with matched controls on the waiting list.

Results

Patients transplanted with DSA class II showed a clear survival benefit compared with matched patients who remained on dialysis or were waitlisted on dialysis/transplanted at 5 years (100%, 34%, and 73%, respectively). After a mean follow-up of 5.5 years, there was no significant difference in death-censored graft survival between transplanted patients without DSA and those with preformed DSA class II (adjusted HR 1.10; 95% confidence interval, 0.41-2.97), although the incidence of rejection was higher in recipients with DSA class II (adjusted HR 5.84; 95% confidence interval, 2.58-13.23; P < 0.001). Serum creatinine levels at 1, 3, and 5 years posttransplant did not differ between groups. No predictors of rejection were found, although patients who received basiliximab induction therapy had higher incidence of rejection (100%) compared with those who received antithymocyte globulin (52%).

Conclusions

We conclude that for highly sensitized patients, deceased-donor kidney transplantation with DSA class II yields a survival benefit over prolonged waiting time on dialysis. Instead of listing DSA class II as unacceptable antigens, an individual approach with further immunologic risk assessment is recommended.

The results of HLA-incompatible kidney transplantation according to pre-transplant crossmatch tests: Donor-specific antibody as a prominent predictor of acute rejection

BACKGROUND

Crossmatching (XM) between organ donors and recipients is correlated with clinical outcomes. This study evaluates the results of HLA-incompatible kidney transplant (HLA-i KT) according to pre-transplant XM modalities.

METHODS

This study included 731 consecutive patients. HLA-i KT was defined as a transplant under conditions of complement-dependent cytotoxicity (CDC) XM positivity, flow-cytometric XM (FCXM) positivity, and/or maximal donor-specific antibody (DSA) mean fluorescence intensity (MFI) ≥5000.

RESULTS

The incidence of antibody-mediated rejection (AMR) within 1 year after transplant was significantly higher in the HLA-i group than in the HLA compatible (HLA-c) group (15 vs 9 patients, 14.2% vs 1.4%; P < 0.01). Multivariate analysis indicated that a DSA MFI ≥5000 (odds ratio [OR] = 2.63; 95% confidence interval [CI], 1.00-6.98; P = 0.05) was significantly associated with acute rejection (AR), whereas CDC (OR = 2.09; 95% CI, 0.55-7.99; P = 0.28) and FCXM positivity (OR = 2.07; 95% CI, 0.73-5.87; P = 0.17) were not. Similarly, DSA MFI ≥ 5000 (OR = 4.14; P = 0.02) was the only significant factor affecting the risk of AMR.

CONCLUSIONS

Of the various XM tests, DSA MFI ≥5000 was the most prominent predictor of AR in patients undergoing HLA-i KT.

Successful kidney transplantation after desensitization in a patient with positive flow crossmatching and donor-specific anti-HLA-DP antibody: A Case report

BACKGROUND

Traditionally, the presence of antibodies against human leukocyte antigen (HLA)-C and DP was considered to be associated with only a low risk of antibody-mediated rejection (ABMR) in kidney transplantation (KT), because the antigenicities of these proteins are weak. However, the clinical effects of HLA-C and -DP donor-specific HLA antibodies (DSHAs) have recently been reevaluated.

METHODS

Here, we report the case of a retransplant patient with positive flow cytometry crossmatch (FCXM) and high level of HLA-DP DSHA who was desensitized using rituximab, plasmapheresis, and intravenous immunoglobulin.

RESULTS

The epitope-based antibody reactivity was identified that the positive B-cell FCXM in our patient was attributable to the specific epitope. The patient underwent a successful retransplantation and has continued to do well for 10 month after KT.

CONCLUSION

If an HLA-DP DSHA is present, it is important to detect any mismatched HLA-DP epitope pretransplantation and to monitor HLA-DP levels carefully. According to previous reports, anti-HLA-DP DSHA can induce ABMR soon after transplantation, but such ABMR can be prevented by pretransplantation desensitization and careful monitoring of DSHA levels.

Effect of delayed graft function, acute rejection and chronic allograft dysfunction on kidney allograft telomere length in patients after transplantation: a prospective cohort study

BACKGROUND

The outcome of kidney allograft transplantation is associated with numerous donor-dependent and recipient-dependent immunological and non-immunological factors. Studies on genetic factors affecting the non-immunological aspects, like ageing of the kidney allograft and patient outcome are still lacking. The aim of this study was the analysis of relative telomere length (RTL; T/S ratio) in the biopsy specimens of the transplanted kidney allograft and its correlation with the delayed graft function (DGF), acute rejection (AR) and chronic allograft dysfunction (CAD).

METHODS

The study enrolled 119 Caucasian kidney allograft recipients (64 M/55 F, mean age 47.32 ± 14.03; transplantation performed between 2001 and 2012). Organs were harvested from cadaveric donors (59.8 M/40.2 F, mean age 45.99 ± 14.62).

RESULTS

There were significant differences in RTL assessed in kidney allograft biopsy specimens collected 3-6 months after transplantation between patients with DGF and without DGF (181.8 ± 82.0 vs. 284.6 ± 149.6; p < 0.05) and in RTL of kidney allograft biopsy specimens collected 18-60 months after transplantation between patients with AR and without AR (188.1 ± 162.1 vs. 263.3 ± 134.7; p = 0.047). There were significant differences in RTL assessed in kidney allograft biopsy specimens collected 12-24 months after transplantation between patients with CAD and without CAD (168.0 ± 120.0 vs. 282.1 ± 158.4; p = 0.038).

CONCLUSIONS

Duration of dialysis before transplantation and PRA influence the kidney allograft ageing. Telomere length assessed in biopsy specimens collected in the peri-transplant period predicts the long-term kidney allograft function. Complications of kidney transplantation, like DGF, AR and CAD are linked with the telomere length and thus, graft ageing.