Optimizing Outcomes in Pediatric Renal Transplantation Through the Australian Paired Kidney Exchange Program.

Kidney paired donation (KPD) programs offer the opportunity to enable living kidney donation when immunological and other barriers prevent safe directed donation. Children are likely to require multiple transplants during their lifetime; therefore, high-level histocompatibility and organ quality matching are key priorities. Details are given for a cohort of seven pediatric renal transplantations performed through the Australian Kidney Exchange (AKX), including barriers to alternative transplantation and outcomes after KPD. Reasons for entering the KPD program were preformed donor-specific antibodies to their registered donor in five cases, ABO mismatch, and avoidance of the risk of exposure to hepatitis B virus. Four recipients were highly sensitized. All patients received transplants with organs of lower immunological risk compared with their registered donors. HLA eplet mismatch scores were calculated for donor-recipient pairs; three patients had improved eplet mismatch load with AKX donor compared with their registered donor. All grafts are functioning, with a mean estimated glomerular filtration rate of 77 mL/min/1.73 m2 (range 46-94 mL) and a follow-up range of 8-54 months, and no patient experienced clinical or histological rejection. KPD is a viable strategy to overcome many barriers to living donation for pediatric patients who have an otherwise suitable donor and provides an opportunity to minimize immunological risks.

HLA Matching at the Eplet Level Protects Against Chronic Lung Allograft Dysfunction.

Donor selection in lung transplantation (LTx) is historically based upon clinical urgency, ABO compatibility, and donor size. HLA matching is not routinely considered; however, the presence or later development of anti-HLA antibodies is associated with poorer outcomes, particularly chronic lung allograft dysfunction (CLAD). Using eplet mismatches, we aimed to determine whether donor/recipient HLA incompatibility was a significant predictor of CLAD. One hundred seventy-five LTx undertaken at the Alfred Hospital between 2008 and 2012 met criteria. Post-LTx monitoring was continued for at least 12 months, or until patient death. HLA typing was performed by sequence-based typing and Luminex sequence-specific oligonucleotide. Using HLAMatchmaker, eplet mismatches between each donor/recipient pairing were analyzed and correlated against incidences of CLAD. HLA-DRB1/3/4/5+DQA/B eplet mismatch was a significant predictor of CLAD (hazard ratio [HR] 3.77, 95% confidence interval [CI]: 1.71-8.29 p < 0.001). When bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS) were analyzed independently, HLA-DRB1/3/4/5 + DQA/B eplet mismatch was shown to significantly predict RAS (HR 8.3, 95% CI: 2.46-27.97 p < 0.001) but not BOS (HR 1.92, 95% CI: 0.64-5.72, p = 0.237). HLA-A/B eplet mismatch was shown not to be a significant predictor when analyzed independently but did provide additional stratification of results. This study illustrates the importance of epitope immunogenicity in defining donor-recipient immune compatibility in LTx.

Comparative analysis of how immune sensitization is defined prior to lung transplantation.

BACKGROUND: Immune sensitization prior to lung transplantation may be associated with worse survival. Using solid phase assays to define sensitization, we assessed the relationship between PRA status, donor specific anti-HLA antibodies (DSA) pre-transplant, cytotoxic cross match results and the clinical outcomes following lung transplantation. METHODS: Luminex assays determined the presence of antibodies to class I and class II MHC molecules prior to lung transplantation. At the time of transplant, the PRA status, the presence of DSA and prospective cytotoxic cross match result were analysed in 195 patients undergoing lung transplantation between June 2008 and June 2012. Clinical outcomes analysed included acute cellular and antibody-mediated rejection, chronic lung allograft dysfunction (CLAD) and mortality. RESULTS: At the time of transplant, 45% of patients had a positive PRA and 29% had DSA. On univariate analysis, the presence of pre-transplant class I or II anti-HLA donor-specific antibodies was not associated with the development of chronic lung allograft dysfunction (CLAD) despite significant associations with PRA status and B-cell crossmatch. CONCLUSION: Defining sensitization using solid phase assays provide additional details regarding donor-specific sensitization but did not provide additional prognostic information to that provided by historically available cell-based cross-match assays.

Solid phase HLA antibody detection technology--challenges in interpretation.

The introduction into routine diagnostic laboratories of solid phase assays for human leukocyte antigen (HLA) antibody detection has resulted in the application of new laboratory matching algorithms in clinical organ transplantation which have improved pre-transplant detection of immunization, in turn resulting in avoidance of rejection in many cases which until their introduction would not have been possible using the historical complement dependent serological techniques. There have been two generations of solid phase assays introduced into routine practice, namely, the enzyme-linked immunosorbent assay (ELISA) technique and the use of fluorescent beads with HLA molecules bound to their surface which can either be used in conventional flow cytometry or in conjunction with Luminex instrumentation, the latter having become the most popular approach. The use of the fluorescent bead techniques has raised interesting questions both with respect to technical performance and the interpretation of the results obtained. The advantages of bead technology for HLA antibody determination and the technical issues requiring resolution are the subject of this review.

A new rat model of thrombotic focal cerebral ischemia.

We developed a fibrin-rich thrombotic focal cerebral ischemic model with reproducible and predictable infarct volume in rats. In male Wistar rats (n = 77), a thrombus was induced at the origin of the middle cerebral artery (MCA) by injection of thrombin via an intraluminal catheter placed in the intracranial segment of the internal carotid artery (ICA). Thrombus induction and consequent ischemic cell damage were examined by histopathological analysis and neurological deficit scoring, and by measuring changes in cerebral blood flow (CBF) using laser-Doppler flowmetery (LDF), perfusion-weighted imaging (PWI), and by diffusion weighted imaging (DWI). Histopathology revealed that a fibrin-rich thrombus localized to the origin of the right MCA. Regional cerebral blood flow (rCBF) in the right parietal cortex was reduced by 34-58% of preinjection levels after injection of thrombin in rats administered 30 U of thrombin (n = 10). Magnetic resonance imaging (MRI) showed a reduction in CBF and a hyperintensity DWI encompassing the territory supplied by the right MCA. The infarct volume in rats administered 80 U of thrombin was 31.29 +/- 12.9% of the contralateral hemisphere at 24 h (n = 13), and 34.7 +/- 16.4% of the contralateral hemisphere at 168 h (n = 6). Rats administered 30 U of thrombin exhibited a hemispheric infarct volume of 34.0 +/- 14.5% (n = 9) at 24 h and 29.7 +/- 13.9% (n = 8) at 168 h. In addition, thrombotic rats (n = 3) treated with recombinant tissue plasminogen activator (rt-PA) (10 mg/kg) 2 h after thrombosis showed that CBF rapidly returned towards preischemic values as measured by PWI. This model of thrombotic ischemia is relevant to thromboembolic stroke in humans and may be useful in documenting the safety and efficacy of thrombolytic intervention as well as for investigating therapies complementary to antithrombotic therapy.

Characteristics of coagulase-negative Staphylococci isolated from bovine intramammary infections.

Coagulase-negative Staphylococci (CNS) isolated from 86 different bovine intramammary infections (IMI) were investigated for their plasmid content, antimicrobial resistance, and infection characteristics. Plasmids were isolated from 30.2% of CNS. Number of plasmid bands ranged from 1 to 5. With the exception of tetracycline resistance, the presence of plasmids was not related to antibiotic resistance. Staphylococcus chromogenes was the CNS most frequently isolated from bovine IMI. Intramammary infections were of long duration (mean = 222 days) and resulted in a low incidence of clinical mastitis (8.1% of IMI). The greatest percentage of IMI (55%) were detected in heifers with 57% of these IMI first detected at calving. A total of 56% of IMI originated during the dry period in second lactation or older cows. The number of plasmid-positive CNS IMI was greater (P < 0.05) in multilactational cows when compared to heifers. The presence of a plasmid-positive CNS had no influence on duration of IMI, origin of IMI, clinical status of the infection, and elimination of IMI.

HLA-DR2 negative narcolepsy in Australian Caucasians: clinical features, serology and sequence specific oligonucleotide typing.

An almost invariable association with HLA-DR2 and DQw1 has previously been reported in Japanese and caucasian narcoleptics. We performed HLA typing in 18 Australian narcoleptics using serological techniques and sequence specific oligonucleotide probes. HLA-DQw1 was present in 15 patients and DR2 in 12; 3 patients with cataplectic narcolepsy were DR2-negative. The serological haplotype most strongly associated with narcolepsy was DRw15 (a subtype of DR2), DQw1. DRw15-positive patients were positive for the alleles DRB1*1501 and DQB1*0602 defined with oligonucleotide probes. We conclude that the association of narcolepsy with DR2 and DQw1 is not as strong as previously reported and the absence of DR2 or DQw1 does not preclude the diagnosis of classical narcolepsy, at least in caucasians. Secondly, DR2-positive narcoleptics possess characteristic serological subtypes and alleles defined with oligonucleotide probes that are also found in normals. Thirdly, the occurrence of DR2-negative cataplectic narcoleptics points to the existence of more than one narcolepsy susceptibility gene.