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Introduction: Ex vivo and in vitro diagnostics, such as interferon-γ (IFN-γ) release enzyme linked ImmunoSpot (ELISpot) and flow cytometry, are increasingly employed in the research and diagnostic setting for severe T-cell mediated hypersensitivity. Despite an increasing use of IFN-γ release ELISpot for drug causality assessment and utilization of a range of antimicrobial concentrations ex vivo , data regarding antimicrobial-associated cellular cytotoxicity and implications for assay performance remain scarcely described in the literature. Using the measurement of lactate dehydrogenase (LDH) and the 7-AAD cell viability staining, we aimed via an exploratory study, to determine the maximal antimicrobial concentrations required to preserve cell viability for commonly implicated antimicrobials in severe T-cell mediated hypersensitivity. Method: After an 18-h incubation of patient peripheral blood monocytes (PBMCs) and antimicrobials at varying drug concentrations, the cell cytotoxicity was measured in two ways. A colorimetric based assay that detects LDH activity and by flow cytometry using the 7-AAD cell viability staining. We used the PBMCs collected from three healthy control participants with no known history of adverse drug reaction and two patients with a rifampicin-associated drug reaction with eosinophilia and systemic symptoms (DRESS), confirmed on IFN-γ ELISpot assay. The PBMCs were stimulated for the investigated drugs at the previously published drug maximum concentration ( Cmax ), and concentrations 10- and 100-fold above. Results: In a human immunodeficiency virus (HIV) negative and a positive rifampicin-associated DRESS with positive ex vivo IFN-γ ELISpot assay, use of 10- and 100-fold Cmax drug concentrations decreased spot forming units/million cells by 32–100%, and this corresponded to cell cytotoxicity of more than 40 and 20% using an LDH assay and 7-AAD cell viability staining, respectively. The other antimicrobials (ceftriaxone, flucloxacillin, piperacillin/tazobactam, and isoniazid) tested in healthy controls showed similar dose-dependent increased cytotoxicity using the LDH assay, but cytotoxicity remained lower than 40% for all Cmax and 10-fold Cmax drug concentrations except flucloxacillin. All 100-fold Cmax concentrations resulted in cell death >40% (median 57%), except for isoniazid. 7-AAD cell viability staining also confirmed an increase in lymphocyte death in PBMCs incubated with 10-fold and 100-fold above Cmax for ceftriaxone, and flucloxacillin; however, piperacillin/tazobactam and isoniazid indicated no differences in percentages of viable lymphocytes across concentrations tested. Conclusion: The LDH cytotoxicity and 7-AAD cell viability staining techniques both demonstrate increased cell death corresponding to a loss in ELISpot sensitivity, with use of higher antimicrobial drug concentrations for ex vivo diagnostic IFN-γ ELISpot assays. For all the antimicrobials evaluated, the use of Cmax and 10-fold Cmax concentrations impacts cell viability and potentially affects ELISpot performance. These findings inform future approaches for ex vivo diagnostics such as IFN-γ release ELISpot.

The association of pro-inflammatory markers such as interleukin-6 (IL-6) and other biomarkers with severe coronavirus disease 2019 (COVID-19) is of increasing interest, however their kinetics, response to current COVID-related treatments, association with disease severity and comparison with other disease states associated with potential cytokine storm (CS) such as Staphylococcus aureus bacteraemia (SAB) are ill-defined. A cohort of 55 hospitalized SARS-CoV-2 positive patients was prospectively recruited - blood sampling was performed at baseline, post-treatment and hospital discharge. Serum IL-6, C-reactive protein (CRP) and other laboratory investigations were compared between treatment groups and across timepoints. Acute serum IL-6 and CRP levels were then compared to those with suspected COVID-19 (SCOVID) and age and sex matched patients with SAB and patients hospitalized for any non-infectious condition (NIC). IL-6 was elevated at admission in the SARS-CoV-2 cohort but at lower levels compared to matched SAB patients. Median (IQR) IL-6 at admission was 73.89 pg/mL (30.9, 126.39) in SARS-CoV-2 compared to 92.76 pg/mL (21.75, 246.55) in SAB (p=0.017); 12.50 pg/mL (3.06, 35.77) in patients with NIC; and 95.51 pg/mL (52.17, 756.67) in SCOVID. Median IL-6 and CRP levels decreased between admission and discharge timepoints. This reduction was amplified in patients treated with remdesivir and/or dexamethasone. CRP and bedside vital signs were the strongest predictors of COVID-19 severity. Knowledge of the kinetics of IL-6 did not offer enhanced predictive value for disease severity in COVID-19 over common investigations such as CRP and vital signs.

Background The use of in vivo and ex vivo diagnostic tools for delayed hypersensitivity reactions (DHRs) associated with iodinated contrast media (ICM) is currently ill-defined. Objective To evaluate the role of in vivo and ex vivo diagnostic tools for DHRs occurring >6 h following intravenous low-osmolality ICM. Methods We conducted a prospective, multicenter, international cohort study. The patients were recruited from two tertiary care adult allergy clinics, Austin Health, Australia and the McGill University Health Centre, Canada. Eligible participants were adults who reported a DHR after receiving ICM. In vivo testing (skin testing and intravenous challenge) was performed to identify an alternative agent. Ex vivo testing using interferon-γ enzyme-linked ImmunoSpot assay was performed in four Australian patients to explore its diagnostic performance. Results The culprit ICM was identified by dIDT in 17/20 (85%) while in 3/20 (15%) a challenge was necessary to confirm delayed hypersensitivity. All patients with a positive dIDT to iohexol were positive to iodixanol (15/15; 100%) while 3/4 (75%), 3/4 (75%), 4/6 (67%), and 3/5 (60%) were positive to iopromide, ioversol, iopamidol, and iobitridol, respectively. Overall, 7/20 (35%) patients tolerated a challenge with an alternative ICM. The IFN-γ release assay was negative for the implicated ICM in 4 patients with confirmed DHR through a positive dIDT. Conclusion dIDT allowed confirmation of T cell-mediated allergy to the implicated ICM in 85% of patients with a strong clinical suspicion of DHR and identification of non-cross-reactive ICM in 35% of patients. The IFN-y ELISpot was not useful in the four patients tested.

[This corrects the article DOI: 10.3389/fphar.2021.640012.].[This corrects the article DOI: 10.3389/fphar.2021.640012.].

The glycosphingolipid isoglobotrihexosylceramide, or isogloboside 3 (iGb3), is believed to be critical for natural killer T (NKT) cell development and self-recognition in mice and humans. Furthermore, iGb3 may represent an important obstacle in xenotransplantation, in which this lipid represents the only other form of the major xenoepitope Galalpha(1,3)Gal. The role of iGb3 in NKT cell development is controversial, particularly with one study that suggested that NKT cell development is normal in mice that were rendered deficient for the enzyme iGb3 synthase (iGb3S). We demonstrate that spliced iGb3S mRNA was not detected after extensive analysis of human tissues, and furthermore, the iGb3S gene contains several mutations that render this product nonfunctional. We directly tested the potential functional activity of human iGb3S by expressing chimeric molecules containing the catalytic domain of human iGb3S. These hybrid molecules were unable to synthesize iGb3, due to at least one amino acid substitution. We also demonstrate that purified normal human anti-Gal immunoglobulin G can bind iGb3 lipid and mediate complement lysis of transfected human cells expressing iGb3. Collectively, our data suggest that iGb3S is not expressed in humans, and even if it were expressed, this enzyme would be inactive. Consequently, iGb3 is unlikely to represent a primary natural ligand for NKT cells in humans. Furthermore, the absence of iGb3 in humans implies that it is another source of foreign Galalpha(1,3)Gal xenoantigen, with obvious significance in the field of xenotransplantation.

IntroductionSevere cutaneous adverse reactions (SCAR) are a group of T cell-mediated hypersensitivities associated with significant morbidity, mortality and hospital costs. Clinical phenotypes include Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalised exanthematous pustulosis (AGEP). In this Australasian, multicentre, prospective registry, we plan to examine the clinical presentation, drug causality, genomic predictors, potential diagnostic approaches, treatments and long-term outcomes of SCAR in Australia and New Zealand.Methods and analysisAdult and adolescent patients with SCAR including SJS, TEN, DRESS, AGEP and another T cell-mediated hypersensitivity, generalised bullous fixed drug eruption, will be prospectively recruited. A waiver of consent has been granted for some sites to retrospectively include cases which result in early mortality. DNA will be collected for all prospective cases. Blood, blister fluid and skin biopsy sampling is optional and subject to patient consent and site capacity. To develop culprit drug identification and prevention, genomic testing will be performed to confirm human leukocyte antigen (HLA) type and ex vivo testing will be performed via interferon-γ release enzyme linked immunospot assay using collected peripheral blood mononuclear cells. The long-term outcomes of SCAR will be investigated with a 12-month quality of life survey and examination of prescribing and mortality data.Ethics and disseminationThis study was reviewed and approved by the Austin Health Human Research Ethics Committee (HREC/50791/Austin-19). Results will be published in peer-reviewed journals and presented at relevant conferences.Trial registration numberAustralian New Zealand Clinical Trials Registry (ACTRN12619000241134).

Background The use of in vivo and ex vivo diagnostic tools for delayed hypersensitivity reactions (DHRs) associated with iodinated contrast media (ICM) is currently ill-defined. Objective To evaluate the role of in vivo and ex vivo diagnostic tools for DHRs occurring >6 h following intravenous low-osmolality ICM. Methods We conducted a prospective, multicenter, international cohort study. The patients were recruited from two tertiary care adult allergy clinics, Austin Health, Australia and the McGill University Health Centre, Canada. Eligible participants were adults who reported a DHR after receiving ICM. In vivo testing (skin testing and intravenous challenge) was performed to identify an alternative agent. Ex vivo testing using interferon-[gamma] enzyme-linked ImmunoSpot assay was performed in four Australian patients to explore its diagnostic performance. Results The culprit ICM was identified by dIDT in 17/20 (85%) while in 3/20 (15%) a challenge was necessary to confirm delayed hypersensitivity. All patients with a positive dIDT to iohexol were positive to iodixanol (15/15; 100%) while 3/4 (75%), 3/4 (75%), 4/6 (67%), and 3/5 (60%) were positive to iopromide, ioversol, iopamidol, and iobitridol, respectively. Overall, 7/20 (35%) patients tolerated a challenge with an alternative ICM. The IFN-[gamma] release assay was negative for the implicated ICM in 4 patients with confirmed DHR through a positive dIDT. Conclusion dIDT allowed confirmation of T cell-mediated allergy to the implicated ICM in 85% of patients with a strong clinical suspicion of DHR and identification of non-cross-reactive ICM in 35% of patients. The IFN-y ELISpot was not useful in the four patients tested. Keywords: Delayed hypersensitivity reactions, Maculopapular exanthema, Drug reaction with eosinophilia and systemic symptoms, Iodinated contrast media, In vivo diagnostic tools, Ex vivo diagnostic tools

The spine is the commonest site of skeletal metastatic disease and uncontrolled growth of cancer in the spine will inevitably cause pain and neurologic compromise. Improved understanding of the pathobiology behind this devastating condition is urgently needed. For this reason, the aim of this study was to establish a clinically relevant, animal model of spinal cancer. A percutaneous orthotopic injection of human breast (MDA-MB-231) or human prostate (PC-3) cancer cells was administered into the upper lumbar spine of nude mice ( n  = 6). Animals were monitored twice daily for general welfare, gait asymmetry or disturbance, and hindlimb weakness. After sacrifice, plain radiographs, micro-CT imaging and histological analysis of the spines were performed on each mouse. All mice recovered fully from the inoculation procedure and displayed normal gait and behaviour patterns for at least 3 weeks post-inoculation. Subsequently, between 3 and 5 weeks post-inoculation, each mouse developed evolving paralysis in their hindlimbs over 48–72 h. All followed the same pattern of decline following onset of neurological dysfunction; from gait asymmetry and unilateral hindlimb weakness, to complete unilateral hindlimb paralysis and finally to complete bilateral hindlimb paralysis. Plain radiographs, micro-CT scanning and histological analysis confirmed local tumour growth and destruction of the spine in all six mice. An in vivo mouse model of human intraosseous spinal cancer has been established forming cancers that grow within the spine and cause epidural spinal cord compression, resulting in a reproducible, evolving neurological deficit and paralysis that closely resembles the human condition.

Naturally occurring anti‐carbohydrate antibodies play a major role in both the innate and adaptive immune responses. To elicit an anti‐carbohydrate immune response, glycoproteins can be processed to glycopeptides and presented by the classical antigen‐presenting molecules, major histocompatibility complex (MHC) Class I and II. In contrast, much less is known about the mechanism(s) for anti‐carbohydrate responses to glycolipids, although it is generally considered that the CD1 family of cell surface proteins presents glycolipids to T cells or natural killer T (NKT) cells. Using model carbohydrate systems (isogloboside 3 and B blood group antigen), we examined the anti‐carbohydrate response on glycolipids using both antibody neutralisation and knockout mouse‐based experiments. These studies showed that CD4+ T cells were required to generate antibodies to the carbohydrates expressed on glycolipids, and unexpectedly, these antibody responses were CD1d and NKT cell independent. They also did not require peptide help. These data provide new insight into glycolipid antigen recognition by the immune system and indicate the existence of a previously unrecognised population of glycolipid antigen‐specific, CD1‐independent, CD4+ T cells.