Identification of 3 novel HLA-B alleles: B*08:173, B*18:72:03 and B*53:05:02.

A total of 3 novel human leukocyte antigen-B (HLA-B) alleles were detected by next generation sequencing and confirmed by monoallelic sequencing.

KIR-associated protection from CMV replication requires pre-existing immunity: a prospective study in solid organ transplant recipients.

Previous studies have associated activating Killer cell Immunoglobulin-like Receptor (KIR) genes with protection from cytomegalovirus (CMV) replication after organ transplantation. Whether KIR-associated protection is operating in the context of primary infection, re-activation, or both, remains unknown. Here we correlated KIR genotype and CMV serostatus at the time of transplantation with rates of CMV viremia in 517 heart (n=57), kidney (n=223), liver (n=165) or lung (n=72) allograft recipients reported to the Swiss Transplant Cohort Study. Across the entire cohort we found B haplotypes-which in contrast to A haplotypes may contain multiple activating KIR genes-to be protective in the most immunosuppressed patients (receiving anti-thymocyte globulin induction and intensive maintenance immunosuppression) (hazard ratio after adjustment for covariates 0.46, 95% confidence interval 0.29-0.75, P=0.002). Notably, a significant protection was detected only in recipients who were CMV-seropositive at the time of transplantation (HR 0.45, 95% CI 0.26-0.77, P=0.004), but not in CMV seronegative recipients (HR 0.59, 95% CI 0.22-1.53, P=0.28). These data indicate a prominent role for KIR-and presumably natural killer (NK) cells-in the control of CMV replication in CMV seropositive organ transplant recipients treated with intense immunosuppression.

[Genetic predispositions in drug allergy: the role of HLA]. / Predispositions génétiques dans l'allergie médicamenteuse: importance du HLA.

The pathophysiology of drug allergy is complex and relies on the interaction between the drug and the immune system in combination with environmental factors, in particular viruses. Genetic predisposition plays an important role in drug allergy. Recent publications have shown the importance of HLA genes, particularly in the delayed hypersensitivity reactions. In fact, particular HLA alleles were identified as risk factors in the development of severe allergic reactions to certain drugs, identifying people at risk of hypersensitivity before initiation of specific treatment. In the future, identification of other alleles in HLA genes will improve patients care by preventing hypersensitivity reactions associated with significant morbidity and mortality.

Smart instrumentation for determination of ligament stiffness and ligament balance in total knee arthroplasty.

Ligament balance is an important and subjective task performed during total knee arthroplasty (TKA) procedure. For this reason, it is desirable to develop instruments to quantitatively assess the soft-tissue balance since excessive imbalance can accelerate prosthesis wear and lead to early surgical revision. The instrumented distractor proposed in this study can assist surgeons on performing ligament balance by measuring the distraction gap and applied load. Also the device allows the determination of the ligament stiffness which can contribute a better understanding of the intrinsic mechanical behavior of the knee joint. Instrumentation of the device involved the use of hall-sensors for measuring the distractor displacement and strain gauges to transduce the force. The sensors were calibrated and tested to demonstrate their suitability for surgical use. Results show the distraction gap can be measured reliably with 0.1mm accuracy and the distractive loads could be assessed with an accuracy in the range of 4N. These characteristics are consistent with those have been proposed, in this work, for a device that could assist on performing ligament balance while permitting surgeons evaluation based on his experience. Preliminary results from in vitro tests were in accordance with expected stiffness values for medial collateral ligament (MCL) and lateral collateral ligament (LCL).

Design and test of a MEMS strain-sensing device for monitoring artificial knee implants.

This paper describes the development of a polyimide-based MEMS strain-sensing device. Finite element analysis was used to investigate an artificial knee implant and assist on device design and to optimize sensing characteristics. The sensing element of the device was fabricated using polyimide micromachining with embedded thin-metallic wires and placed into a knee prosthesis. The device was evaluated experimentally in a mechanical knee simulator using static and dynamic axial load conditions similar to those encountered in vivo. Results indicates the sensor is capable of measuring the strain associated to the total axial forces in the range of approximately 4 times body weight with a good sensitivity and accuracy for events happening within 1 s time window.

Transplanted human pancreatic islets after long-term insulin independence.

Long-term insulin independence after islets of Langerhans transplantation is rarely achieved. The aims of this study were to identify the histological and immunological features of islets transplanted in a type 1 diabetic patient who died of a cerebral hemorrhage after >13 years insulin independence. Islets were pooled from two donors with respectively one and five HLA mismatches. Insulin-positive islets were found throughout the right and left liver, and absent in the pancreas. Two- and three-dimensional analysis showed that islets lost their initial rounded and compact morphology, had a mean diameter of 136 µm and were constituted of an unfolded epithelial band of 39.1 µm. Leukocyte phenotyping showed no evidence of a tolerogenic environment in the islet-containing portal spaces. Finally, HLA typing of microdissected islets showed HLA from the best matched donor in all 23 microdissection samples, compared to 1/23 for the least matched donor. This case report demonstrates that allogeneic islets can survive over 13 years while maintaining insulin independence. Allogeneic islets had unique morphologic features and implanted in the liver regardless of their size. Finally, our results suggest that, in this case, rejection had been prevalent over autoimmunity, although this hypothesis warrants further investigation.

Detection of anti-HLA antibodies by solid-phase assay in kidney transplantation: friend or foe?

Pre-formed and de novo anti-human leukocyte antigen (HLA) antibodies induce antibody-mediated rejection and are also involved in mechanisms leading to chronic graft nephropathy. The detection of anti-HLA antibodies by solid-phase assay (SPA) has revolutionized the management of immunized patients before and after kidney transplantation. Characterized by high sensitivity and specificity, the clinical relevance of anti-HLA antibodies by SPA has to be clarified. The presence of donor-specific antibody at the epitope level, their titer, and the use of different crossmatch technologies could help to determine which of the anti-HLA antibodies are friends and which are foes in kidney transplantation. In this review, we summarize the current state of the art on this debated topic, and give clinical guidelines for the management of antibody detection pre- and post-transplantation, based on these evidences and our own clinical expertise.

Pretransplant HLA mistyping in diagnostic samples of acute myeloid leukemia patients due to acquired uniparental disomy.

Although acquired uniparental disomy (aUPD) has been reported in relapse acute myeloid leukemia (AML), pretransplant aUPD involving chromosome 6 is poorly documented. Such events could be of interest because loss of heterozygosity (LOH) resulting from aUPD in leukemic cells may lead to erroneous results if HLA typing for hematopoietic stem cell donor searches is performed on blood samples drawn during blastic crisis. We report here six AML patients whose HLA typing was performed on DNA extracted from peripheral blood obtained at diagnosis. We observed LOH involving the entire HLA region (three patients), HLA-A, B, C (two patients) and HLA-A only (one patient). An array-comparative genomic hybridization showed that copy number was neutral for all loci, thus revealing partial aUPD of chromosome 6p21. When HLA typing was performed on remission blood samples both haplotypes were detected. A 3-4% LOH incidence was estimated in AML patients with high blast counts. Based on DNA mixing experiments, we determined by PCR sequence-specific oligonucleotide hybridization on microbeads arrays a detection threshold for HLA-A, B, DRB1 heterozygosity in blood samples with <80% blasts. Because aUPD may be partial, any homozygous HLA result should be confirmed by a second typing performed on buccal swabs or on blood samples from the patient in remission.

Eculizumab in acute recurrence of thrombotic microangiopathy after renal transplantation.

Renal thrombotic microangiopathy (TMA) is a severe complication of systemic lupus erythematosus (SLE), which is associated with the presence of antiphospholipid (aPL) antibodies. In its most fulminant form, TMA leads to a rapid and irreversible end-stage renal failure. Eculizumab, an anti-C5 monoclonal antibody, is a novel therapy of choice for patients with paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome. Here, we report the case of a 27-year-old woman, known for SLE and end-stage renal disease due to fulminant TMA. Both aPL antibodies and antinucleosome antibodies were positive. The patient underwent a living-related kidney transplantation with immediate production of urine. Although serum creatinine was remaining high, a graft biopsy, performed on day 6, demonstrated a TMA recurrence. Despite a treatment with plasma exchange, the situation got worse and dialysis was started. Eculizumab treatment was subsequently administered and renal function improved rapidly. Three months after transplantation, serum creatinine was at 100 µmol/L, without proteinuria. This case illustrates the benefit of eculizumab therapy in a fulminant recurrence of TMA after kidney transplantation, resistant to classical therapy.

De novo anti-HLA antibody after pandemic H1N1 and seasonal influenza immunization in kidney transplant recipients.

In solid organ transplanted patients, annual influenza immunization is strongly recommended because of morbidity and mortality of influenza infections. In 2009, the rapid spread of a novel H1N1 influenza A virus led to the accelerated development of novel pandemic influenza vaccines. In Switzerland, the recipients received one dose of seasonal influenza and two doses of AS03-adjuvanted H1N1 vaccines. This situation provided a unique opportunity to analyze the influence of novel adjuvanted influenza vaccines on the production of de novo anti-HLA antibodies. We prospectively followed two independent cohorts including 92 and 59 kidney-transplanted patients, assessing their anti-HLA antibodies before, 6 weeks and 6 months after vaccination. Sixteen of 92 (17.3%) and 7 of 59 (11.9%) patients developed anti-HLA antibodies. These antibodies, detected using the single antigen beads technology, were mostly at low levels and included both donor-specific and non-donor-specific antibodies. In 2 of the 20 patients who were followed at 6 months, clinical events possibly related to de novo anti-HLA antibodies were observed. In conclusion, multiple doses of influenza vaccine may lead to the production of anti-HLA antibodies in a significant proportion of kidney transplant recipients. The long-term clinical significance of these results remains to be addressed.

Telomeric rather than centromeric activating KIR genes protect from cytomegalovirus infection after kidney transplantation.

Cytomegalovirus (CMV) infection is a common complication after organ transplantation. Previous studies have demonstrated that activating killer-cell immunoglobulin-like receptors (KIR) may reduce the rate of CMV infection. KIR genes can be divided into haplotype A (containing a fixed set of inhibitory receptors) and haplotype B (carrying additional activating KIR genes). The KIR locus is divided into a centromeric and a telomeric portion, both of which may carry A or B haplotype motifs. We studied a cohort of 339 kidney transplant recipients to elucidate which KIR genes protect from CMV infection. CMV infection occurred in 139 patients (41%). Possession of telomeric (hazard ratio 0.64, 95% confidence interval 0.44-0.94, p = 0.02) but not centromeric (HR 0.86, 95% CI 0.60-1.23, p = 0.41) B motifs was associated with statistically significant protection from CMV infection. Due to linkage disequilibrium, we were not able to identify a single protective gene within the telomeric B complex (which may contain the KIR2DS1, KIR3DS1, KIR2DL5A and KIR2DS5 genes). The presence of known or putative ligands to activating KIR did not significantly modify the influence of telomeric B group genes. We confirm that B haplotypes protect from CMV infection after kidney transplantation and show that this arises from telomeric B haplotype genes.

New measurement system for on line in core high-energy neutron flux monitoring in materials testing reactor conditions.

Flux monitoring is of great interest for experimental studies in material testing reactors. Nowadays, only the thermal neutron flux can be monitored on line, e.g., using fission chambers or self-powered neutron detectors. In the framework of the Joint Instrumentation Laboratory between SCK-CEN and CEA, we have developed a fast neutron detector system (FNDS) capable of measuring on line the local high-energy neutron flux in fission reactor core and reflector locations. FNDS is based on fission chambers measurements in Campbelling mode. The system consists of two detectors, one detector being mainly sensitive to fast neutrons and the other one to thermal neutrons. On line data processing uses the CEA depletion code DARWIN in order to disentangle fast and thermal neutrons components, taking into account the isotopic evolution of the fissile deposit. The first results of FNDS experimental test in the BR2 reactor are presented in this paper. Several fission chambers have been irradiated up to a fluence of about 7 × 10(20) n∕cm(2). A good agreement (less than 10% discrepancy) was observed between FNDS fast flux estimation and reference flux measurement.

Sequence of a novel HLA-A2 allele in a haematopoietic stem cell donor of the international registry.

We report here the sequence of a new human leucocyte antigen-A2 allele, A*9251, identified in a volunteer haematopoietic stem cell donor of the international registry. A*9251 differs from A*02010101 by two nucleotides at codons 113-114, resulting in a single His>Asp substitution at codon 114.

Long-term insulin-independence after allogeneic islet transplantation for type 1 diabetes: over the 10-year mark.

Results of islet of Langerhans transplantation have markedly improved in recent years, but most patients still lose insulin independence in the long-term. We report herein the longest (over 11 years) case of insulin independence after allogeneic islet transplantation. The subject had a 27-year history of type 1 diabetes and received a single islet-after-kidney graft of 8800 islet equivalents (IEQ)/kg, pooled from 2 donors. Insulin was discontinued by 3 months posttransplant and the patient has remained off insulin ever since. Yearly follow-up studies have revealed normal metabolic control, including normal oral glucose tolerance test (OGTT). Reasons for success may involve choice of immunosuppression, low metabolic demand and low immune responsiveness as suggested by an excellent HLA matching and a high count of circulating regulatory T cells. This observation is so far an exceptional case, but clearly demonstrates the validity of the concept that long-term insulin independence after allogeneic islet transplantation is an achievable target.

Natural killer cell receptor repertoire and their ligands, and the risk of CMV infection after kidney transplantation.

Cytomegalovirus (CMV) infection is the most common viral complication after solid organ transplantation (SOT). Whilst current immunosuppression is known to impair antiviral-specific T-cell immunity in SOT, a potential role for natural killer (NK) cells not affected by immunosuppressive therapy remains to be determined. To address this, we compared the genotype of the NK immunoglobulin-like receptor (KIR) genes and their HLA cognate ligands to the rate of CMV infection in 196 kidney transplant recipients. We have shown that the absence of the HLA-C ligand for inhibitory KIR and the presence of activating KIR genes in the recipients were both associated with a lower rate of CMV infection after transplantation. In a cohort of 17 recipients with acute CMV infection, NK cells were phenotyped over a period of time after diagnosis by their expression profile of C-type lectin receptors and capacity to secrete IFN-gamma. The increased expression of the activating C-type lectin receptors NKG2C and NKG2D was paralleled by the decreased IFN-gamma secretion during the early phase of CMV infection. In conclusion, our findings suggest that KIR/HLA genotype and expression of NKG2C and NKG2D might play a significant role in regulating NK cell function and anti-CMV immunity after kidney transplantation.

A new HLA-DR4 allele, DRB1*0474, with an unusual residue at position 77.

We report here a new DR4 allele, DRB1*0474, identified in a volunteer hematopoietic stem cell donor of the Swiss National Registry. DRB1*0474 differs from DRB1*040701 by two nucleotide residues resulting in a single Thr --> Asn substitution at codon 77.