Assessing Antibody Strength: Comparison of MFI,C1q,and Titer Information

The presence of donor‐specific HLA antibodies before or after transplantation may have different implications based on the antibody strength. Yet, current approaches do not provide information regarding the true antibody strength as defined by antigen–antibody dissociation rate. To assess currently available methods, we compared between neat mean fluorescence intensity (MFI) values, C1q MFI values, ethylenediaminetetraacetic acid (EDTA)‐treated samples, as well as titration studies and peak MFI values of over 7000 Luminex‐based single‐antigen HLA antibody data points. Our results indicate that neat MFI values do not always accurately depict antibody strength. We further showed that EDTA treatment (6%) does not always remove all inhibitory factors compared with C1q or titration studies. In this study of patients presenting with multiple antibody specificities, a prozone effect was observed in 71% of the cohort (usually not affecting all antibody specificities within a single serum sample, though). Similar to titration studies, the C1q assay was able to address the issue of potential inhibition; however, its limitation is its low sensitivity and inability to detect the presence of weak antibodies. Titration studies are the only method among the approaches used in this study to provide information suggesting antigen–antibody dissociation rates and are, therefore, likely to provide better indication of true antibody strength.     

Tissue-associated self-antigens containing exosomes: Role in allograft rejection

Exosomes are extracellular vesicles that express self-antigens (SAgs) and donor human leukocyte antigens. Tissue-specific exosomes can be detected in the circulation following lung, heart, kidney and islet cell transplantations. We collected serum samples from patients who had undergone lung (n?=?30), heart (n?=?8), or kidney (n?=?15) transplantations to isolate circulating exosomes. Exosome purity was analyzed by Western blot, using CD9 exosome-specific markers. Tissue-associated lung SAgs, collagen V (Col-V) and K-alpha 1 tubulin (Kα1T), heart SAgs, myosin and vimentin, and kidney SAgs, fibronectin and collagen IV (Col-IV), were identified using western blot. Lung transplant recipients diagnosed with bronchiolitis obliterans syndrome had exosomes with higher expression of Col-V (4.2-fold) and Kα1T (37.1-fold) than stable. Exosomes isolated from heart transplant recipients diagnosed with coronary artery vasculopathy had a 3.9-fold increase in myosin and a 4.7-fold increase in vimentin compared with stable. Further, Kidney transplant recipients diagnosed with transplant glomerulopathy had circulating exosomes with a 2-fold increased expression of fibronectin and 2.5-fold increase in Col-IV compared with stable. We conclude that circulating exosomes with tissue associated SAgs have the potential to be a noninvasive biomarker for allograft rejection.     

Preclinical and clinical studies for transplant tolerance via the mixed chimerism approach

Based upon observations in murine models, we have developed protocols to induce renal allograft tolerance by combined kidney and bone marrow transplantation (CKBMT) in non-human primates (NHP) and in humans. Induction of persistent mixed chimerism has proved to be extremely difficult in major histocompatibility complex (MHC)-mismatched primates, with detectable chimerism typically disappearing within 30–60?days. Nevertheless, in MHC mismatched NHP, long-term immunosuppression-free renal allograft survival has been achieved reproducibly, using a non-myeloablative conditioning approach that has also been successfully extended to human kidney transplant recipients. CKBMT has also been applied to the patients with end stage renal disease with hematologic malignancies. Renal allograft tolerance and long-term remission of myeloma have been achieved by transient mixed or persistent full chimerism. This review summarizes the current status of preclinical and clinical studies for renal and non-renal allograft tolerance induction by CKBMT. Improving the consistency of tolerance induction with less morbidity, extending this approach to deceased donor transplantation and inducing tolerance of non-renal transplants, are critical next steps for bringing this strategy to a wider range of clinical applications.     

Arterial stenosis in antiphospholipid syndrome: Update on the unrevealed mechanisms of an endothelial disease

First described in 1983, antiphospholipid syndrome (APS) is an autoimmune condition characterized by the occurrence of recurrent arterial and/or venous thrombosis, and/or pregnancy morbidity, in the setting of persistent presence of antiphospholipid antibodies (aPL). While thrombosis is the most well-known pathogenic mechanism in this disorder, the relevance of some other mechanisms such as arterial stenosis is being increasingly recognized. Arterial stenosis has been first described in the renal arteries in patients with APS, however intracranial and coeliac arteries can also be involved with various and treatable clinical manifestations. The underlying pathophysiology of this stenotic arterial vasculopathy is not fully understood but some recent studies revealed new insights into the molecular mechanism behind this endothelial cell activation in APS. In this review, we discuss these newly discovered mechanisms and highlight the diagnostic and therapeutic modalities of the APS related arterial stenosis.     

Tocilizumab and refractory Takayasu disease: Four case reports and systematic review

Background

Relapses upon corticosteroids tapering and immunosuppressive agents are frequent in Takayasu arteritis (TA). Interleukin-6 is highly involved in physiopathology of TA. Many reports showed efficacy of tocilizumab (TCZ) in refractory TA cases. We report four cases and an updated literature review on the TCZ efficacy and safety in patients with TA.

Children suspected of having intracranial infection with normal brain magnetic resonance imaging may be associated with the myelin oligodendrocyte glycoprotein antibody

PurposeTo confirm whether encephalitis due to unknown causes but with normal brain magnetic resonance imaging (MRI) may be associated with the myelin oligodendrocyte glycoprotein (MOG) antibody.MethodsWe retrospectively analyzed and summarized the characteristics of three patients initially suspected of having intracranial infections with normal brain MRI, and ultimately tested positive for anti-MOG antibody.ResultsThe three patients mainly presented with long-term fever accompanied by headaches and drowsiness. Auxiliary examinations showed obvious leukocytosis in peripheral blood and leukocytosis and increased protein expression in cerebrospinal fluid (CSF); furthermore, brain MRI was normal. These findings suggested intracranial infection, especially bacterial meningitis. No patient showed a response to prolonged anti-bacterial therapy; however, they recovered with glucocorticoid therapy, which was prescribed after anti-MOG antibodies were detected in the serum and CSF samples.ConclusionAnti-MOG antibody detection should be performed early for patients with suspected encephalitis due to unknown causes with normal brain MRI, to identify whether they have MOG antibody-associated diseases (MOGAD).     

Reduced specificity of Erns antibody ELISAs for samples from piglets with maternally derived antibodies induced by vaccination of sows with classical swine fever marker vaccine CP7_E2alf

Successful implementation of marker vaccines against classical swine fever virus is dependent on a reliable accompanying diagnostic assay that allows differentiation of infected from vaccinated animals (DIVA ) as well as the development of a testing scheme during emergency vaccination. In this context, special attention needs to be paid to breeding farms, because the offspring of marker vaccinated sows possess maternally derived antibodies (MDA s). So far, limited information is available on the influence of MDA s on serological testing in the context of a DIVA strategy. Therefore, two commercially available E^rns antibody ELISA s were compared, using serum samples of piglets with a high‐to‐moderate titre of MDA s against marker vaccine CP 7_E2alf. False‐positive results were detected by both E^rns antibody ELISA s for serum samples of piglets with an age of up to 4 weeks. Interestingly, most samples tested false‐positive in the first E^rns antibody ELISA were identified correctly by the other E^rns antibody ELISA and vice versa. In conclusion, in case of emergency vaccination of sows, the specificity of both ELISA s in newborn piglets younger than 4 weeks may be relatively low. This could be addressed in a testing strategy by either not sampling piglets up to the age of 4 weeks or using both ELISA s in a screening‐confirmation set‐up.     

A prospective,iterative, adaptive trial of carfilzomib‐based desensitization

Proteasome inhibitor–based strategies hold promise in transplant but have yielded varying results. Carfilzomib, a second‐generation proteasome inhibitor, may possess advantages over bortezomib, the first‐generation proteasome inhibitors. The purpose of this study was to evaluate the safety, toxicity, and preliminary efficacy of carfilzomib in highly HLA‐sensitized kidney transplant candidates. Renal transplant candidates received escalating doses of carfilzomib followed by plasmapheresis (group A) or an identical regimen with additional plasmapheresis once weekly before carfilzomib dosing. Thirteen participants received carfilzomib, which was well tolerated with most adverse events classified as low grade. The safety profile was similar to bortezomib desensitization; however, neurotoxicity was not observed with carfilzomib. Toxicity resulted in permanent dose reduction in 1 participant but caused no withdrawals or deaths. HLA antibodies were substantially reduced with carfilzomib alone, and median maximal immunodominant antibody reduction was 72.8% (69.8% for group A, P = .031, 80.1% for group B, P = .938). After depletion, rebound occurred rapidly and antibody levels returned to baseline between days 81 and 141. Bone marrow studies revealed that approximately 69.2% of plasma cells were depleted after carfilzomib monotherapy. Carfilzomib monotherapy–based desensitization provides an acceptable safety and toxicity profile while leading to significant bone marrow plasma cell depletion and anti‐HLA antibody reduction.