Strength of Donor-Specific Antibodies With the Use of Luminex Single-Antigen Beads Is a Reliable Predictor of Acute Rejection in Living-Relative Kidney Recipients

Can the Toll-like receptors 4 expression in peripheral blood mononuclear cells help assess the effectiveness of immunosuppression and the chance of a future good renal transplant function?

BACKGROUND

A small percentage of peripheral blood mononuclear cells (PBMCs) circulating during the kidney transplantation (KT) period remain in the blood long after transplantation. A part of the PBMCs penetrates the graft.

AIM

To examine if the choice of immunosuppression may change TLR4ex and how TLR4ex affects the transplant function in the future.

MATERIAL

The study population-143 transplanted patients (pts) (55 females, 88 males), mean age on recruitment day 50.33 ± 12.8 years old, mean BMI 25.04 ± 4.18. 41 pts. experienced delayed graft function (DGF+). 55 pts. were treated with cyclosporine A (CsA) and 88 with tacrolimus (Tac). All were treated with mofetil mycophenolate (MMF). The PBMCs acquisition and starting point of the follow-up (TLR-day) was at least one month after KT.

METHOD

We investigated averaged mRNA expression of Toll-like receptors 4 (TLR4ex) in non-stimulated peripheral blood mononuclear cells with the use of real-time polymerase chain reaction. The KT pts. (All, Tac, CsA, DGF+) were divided by the respective median of their TLR4ex (lower: L-TLR4ex, higher: H-TLR4ex). Main clinical parameters and transplant biopsy files (if available) were assessed on TLR-day and post follow-up.

RESULTS

We found that TLR4ex was reduced for a long time in patients who experienced delayed graft function. L-TLR4ex had a higher proportion of DGF+ patients, and patients treated with CsA but lower of those treated with Tac than in H-TLR4ex. The amplitude of changes in renal function parameters (ΔEGFR%/ΔsCr/ΔsCr%) was clearly less favorable for L-TLR4ex. Tacrolimus expressed a stabilizing effect. Both the positive vasculitis score and chronic graft nephropathy were more frequent in the L-TLR4ex group. On TLR-day an association of renal function and Tac concentration with TLR4ex was clear only in the tacrolimus population. The TLR4ex was lower in patients with a future deterioration of the graft function.

CONCLUSION

In kidney transplant recipients the occurrence of DGF results in a long-term reduction of the averaged TLR4ex in PBMC. Tacrolimus exerts a clear, stabilizing, positive and dose-dependent effect on TLR4ex. An improvement in renal transplant function may be expected in KT patients with high TLR4ex. Evaluation of the averaged TLR4ex can be used to assess the efficacy of immunosuppression in the treatment with tacrolimus and to estimate the likelihood of deterioration in renal function.

New DQA1 allele specific antibody against epitope 2D (an exon 1 encoded amino acid). Considerations for alleles under the same P-group designation

The majority of polymorphisms of the Human Leukocyte Antigen (HLA) proteins are clustered at the peptide binding domain (PBD), defined as the area coded by exon 2 and 3 for class I and exon 2 for class II. HLA alleles with the same amino acid (AA) sequence at the PBD are considered functionally equivalent and can be grouped under the same P-group designation. Here we present a case of a kidney recipient, typed as DQA1*01:04, 01:05 and DQB1*05:01P, 05:03, who developed antibodies against all DQ antigens on our Luminex Single Antigen (LSA) panel. Our LSA panel does not include DQA1*01:05 or 01:04, but both alleles belong to the DQA1*01:01P group and beads carrying DQA1*01:01 tested positive. Mature protein sequence alignment demonstrated a single AA mismatch between DQA1*01:04/01:05 and DQA1*01:01 located at position 2 (G vs D), which is encoded by exon 1. Luminex assay by another manufacturer which include a bead carrying patient's own DQA1* type and crossmatch studies with surrogate donors confirmed the presence of an antibody against mismatched epitope 2D. This case illustrates that alleles included in the same P-group may have polymorphisms able to trigger immunological responses and brings attention to the fact that some mature HLA proteins express AA encoded by exon 1, which is structurally part of the PBD.

Expression of PBMC TLR4 in Renal Graft Recipients Who Experienced Delayed Graft Function Reflects Dynamic Balance Between Blood and Tissue Compartments and Helps Select a Problematic Patient

Both Toll-like receptor 4 (TLR4) and monocytes focus stimuli, causing them to contribute differently to chronic injury of a transplanted kidney.

AIM

The aim of our study was to determine if TLR4 monocyte is a diagnostic tool and possibly a target for therapeutic intervention.

MATERIALS

We studied 143 kidney transplant (KT) patients (88 male, 55 female; 50.3 ± 12.8 years); median was 10.4 post KT, follow-up was 11.4 months, and 46 patients had delayed graft function (DGF+) history. Control group (38 healthy volunteers) had monocyte mRNA-TLR4 expression (TLR4ex). DGF+ were divided by median of TLR4ex (-0.1034) into 2 groups: low-TLR4 expression (L-TLR4ex) and high-TLR4 expression (H-TLR4ex).

RESULTS

We showed that in comparison with DGF-, the DGF+ had much lower TLR4ex, and worse KT function both currently (TLR-day) (serum creatinine [sCr] P = .002; estimated glomerular filtration rate [eGFR] P = .001) and post follow-up (sCr P = .006; eGFR P = .005). The DGF+ with L/H-TLR4ex comparison showed no differences in TLR-day KT function but did show differences in post follow-up (sCr P = .01; eGFR P = .02; ΔeGFR% P = .001). Regression analysis showed an association between recipient age, tacrolimus concentration, and uremic milieu (ie, TLR-day sCr and GFR with TLR4ex). Reverse regression analysis indicated an association of TLR4ex (especially L/H-TLR4ex) with post follow-up parameters of KT function and numeric/qualitative measures of change.

CONCLUSION

DGF affects the fate of a graft. Within a several months after transplantation, TLR4ex of peripheral blood mononuclear cells declines in DGF patients. Low LR4ex in patients with DGF+ is associated with poor prognosis for the efficiency of the KT. In patients with DGF+, the proper selection of immunosuppression (tacrolimus dosing) is very important. Higher concentrations of tacrolimus may improve prognosis. The analysis of TLR4ex change may be a useful parameter for the real assessment of immunosuppression efficacy. It is important for transplanted organ function that peripheral blood mononuclear cells effectively leave circulation and remain in the graft.

Human Leukocyte Antigen Sensitization in Solid Organ Transplantation: A Primer on Terminology, Testing, and Clinical Significance for the Apheresis Practitioner

The human leukocyte antigen (HLA) system is an important immunologic barrier that must be considered for successful solid organ transplantation. Formation of donor-specific HLA antibodies in solid organ transplantation is an important cause of allograft injury and may contribute to recipient morbidity and mortality. Therapeutic plasma exchange is often requested to lower HLA antibody levels prior to or after transplantation and for management of HLA antibodies in the context of organ rejection. In this review, we summarize the current terminology, laboratory testing, and clinical significance of HLA sensitization in the solid organ transplant population. Furthermore, to illustrate applications of HLA testing in clinical practice, we summarize our own lung and kidney institutional protocols for managing HLA antibodies in the peri-transplant setting.

Disparate rates of acute rejection and donor-specific antibodies among high-immunologic risk renal transplant subgroups receiving antithymocyte globulin induction

Lymphocyte-depleting induction lowers acute rejection (AR) rates among high-immunologic risk (HIR) renal transplant recipients, including African Americans (AAs), retransplants, and the sensitized. It is unclear whether different HIR subgroups experience similarly low rates of AR. We aimed to describe the incidence of AR and de novo donor-specific antibody (dnDSA) among HIR recipients categorized by age, race, or donor type. All received antithymocyte globulin (ATG) induction and triple maintenance immunosuppression. A total of 464 HIR recipients from 2007 to 2014 were reviewed. AR and dnDSA rates at 1 year for the entire population were 14% and 27%, respectively. AR ranged from 6.7% among living donor (LD) recipients to 30% in younger AA deceased donor (DD) recipients. De novo donor-specific antibody at 1 year ranged from 7% in older non-AA LD recipients to 32% in AAs. AA race remained as an independent risk factor for AR among DD recipients and for dnDSA among all HIR recipients. Development of both AR and dnDSA within the first year was associated with a 54% graft survival at 5 years and was an independent risk factor for graft loss. Despite utilization of recommended immunosuppression for HIR recipients, substantial disparities exist among subgroups, warranting further consideration of individualized immunosuppression in certain HIR subgroups.