Identification of a 17 kDa protein that is a potentially novel antigen of lettuce-associated respiratory allergy in farmers

BACKGROUND

We have identified and reported a novel antigen, nonprotein-specific secreted EP1-like glycoprotein (51 kDa), for lettuce-related respiratory allergy.

OBJECTIVE

We aimed to identify a novel antigen for lettuce-related respiratory allergy that is different from epidermis-specific secreted EP1-like glycoprotein.

METHODS

Immunoblotting was performed using an immunoglobulin E-specific antibody. The antigen-antibody reaction was confirmed by means of enzyme-linked immunosorbent assaying. LC-MS/MS analysis was carried out to detect a novel protein found in sera from 3 of 13 patients with lettuce-related respiratory allergy. Finally, we purified a novel protein from Escherichia coli.

RESULTS

Immunoblotting assays showed common bands of 17 kDa in the sera of 3 of 13 patients. An enzyme-linked immunosorbent assay confirmed that the patient sera reacted with lettuce latex juice. A 17 kDa protein band that showed antigenic reactivity in 3 of 13 patient sera was identified as a kirola-like protein by LC-MS/MS. In addition, although we purified this protein, we failed to show the inhibitory effect.

CONCLUSION

A 17 kDa protein that is a potentially novel antigen of lettuce-associated respiratory allergy was identified. In further studies, we will focus on purifying this novel protein to diagnose lettuce allergy.

Fast and cost-effective protocol to produce Paracoccidioides spp. antigens

INTRODUCTION

The existing methods for Paracoccidioides spp. antigen production are problematic in terms of standardization, specificity, stability, repeatability, and reproducibility.

OBJECTIVE

To optimize the methodology for Paracoccidioides spp. antigen production and evaluate its applicability in paracoccidioidomycosis immunodiagnosis.

MATERIALS AND METHODS

The antigens were obtained from Paracoccidioides lutzii isolates (01, 66, and 8334), Paracoccidioides brasiliensis sensu stricto (113), and Paracoccidioides restripiensis (B-339). These fungi were grown at 36 °C ± 1 °C, on modified Fava-Netto agar, according to Freitas et al. (2018). Paracoccidioides lutzii antigens were obtained after , 10, and 20 days of culture, whereas P. brasiliensis and P. restripiensis antigens were obtained after 10 days. Antigens were evaluated in natura, 10 and 20 times concentrated. Antigenic capacity was evaluated using a double immunodiffusion assay against serum samples from patients with paracoccidioidomycosis, histoplasmosis, and aspergillosis, and random blood donors.

RESULTS

Cross-reactivity between Paracoccidioides spp. antigens was observed when P. brasiliensis, P. restrepiensis antigens, and P. lutzii antigens were evaluated with the polyclonal antibodies against P. lutzii and P. brasiliensis, respectively. No cross-reactivity was obtained for polyclonal antibodies against Histoplasma capsulatum, Aspergillus fumigatus, and random blood donors. The proposed protocol allowed stable, repeatable, and reproducible genus-specific antigen production at a low cost and in a short cultivation time.

CONCLUSION

The proposed protocol allowed us to obtain genus-specific antigens that can be developed and reproduced in all laboratories in Brazil and South America, where paracoccidioidomycosis is a neglected disease, contributing to an early diagnosis, especially in endemic regions, regardless of the species.

Long COVID following mild SARS-CoV-2 infection: characteristic T cell alterations and response to antihistamines

Long COVID is characterized by the emergence of multiple debilitating symptoms following SARS-CoV-2 infection. Its etiology is unclear and it often follows a mild acute illness. Anecdotal reports of gradual clinical responses to histamine receptor antagonists (HRAs) suggest a histamine-dependent mechanism that is distinct from anaphylaxis, possibly mediated by T cells, which are also regulated by histamine. T cell perturbations have been previously reported in post-viral syndromes, but the T cell landscape in patients who have recovered from mild COVID-19 and its relationship to both long COVID symptoms and any symptomatic response to HRA remain underexplored. We addressed these questions in an observational study of 65 individuals who had recovered from mild COVID-19. Participants were surveyed between 87 and 408 days after the onset of acute symptoms; none had required hospitalization, 16 had recovered uneventfully, and 49 had developed long COVID. Symptoms were quantified using a structured questionnaire and T cell subsets enumerated in a standard diagnostic assay. Patients with long-COVID had reduced CD4+ and CD8+ effector memory (EM) cell numbers and increased PD-1 (programmed cell death protein 1) expression on central memory (CM) cells, whereas the asymptomatic participants had reduced CD8+ EM cells only and increased CD28 expression on CM cells. 72% of patients with long COVID who received HRA reported clinical improvement, although T cell profiling did not clearly distinguish those who responded to HRA. This study demonstrates that T cell perturbations persist for several months after mild COVID-19 and are associated with long COVID symptoms.

Performance of Antigen-Based Testing as Frontline Diagnosis of Symptomatic COVID-19

Background and Objectives: To evaluate the performance of antigen-based detection tests as the frontline diagnosis of coronavirus disease 2019 (COVID-19). Materials and Methods: We conducted a nationwide retrospective cohort study in Mexico. A cross-sectional analysis of a cohort study was conducted in Mexico and data from 15,408 suspected (all of them symptomatic) cases of COVID-19 were analyzed. The results of antigen-based tests were compared with those obtained by molecular (polymerase chain reaction-based) assays. Results: The antigen-based tests showed sensitivity below 50% and high specificity in all the analyzed age groups. The highest Youden index (J) was observed among adults aged 25-44 years old (45.5, 95% CI 43.7-47.3). Conclusions: We documented the poor performance of serologic techniques as frontline diagnosis of symptomatic COVID-19 and inaccurate results may impact negatively on pandemic progression.

Flipped Quick-Response Code Enables Reliable Blood Grouping

Accurate and rapid blood typing plays a vital role in a variety of biomedical and forensic scenarios, but recognizing weak agglutination remains challenging. Herein, we demonstrated a flipping identification with a prompt error-discrimination (FLIPPED) platform for automatic blood group readouts. Bromocresol green dye was exploited as a characteristic chromatography indicator for the differentiation of plasma from whole blood by presenting a teal color against a brown color. After integrating these color changes into a quick-response (QR) code, prompt typing of ABO and Rhesus groups was automatically achieved and data could be uploaded wirelessly within 30 s using a commercially available smartphone to facilitate blood cross-matching. We further designed a color correction model and algorithm to remove potential errors from scanning angles and ambient light intensities, by which weak agglutination could be accurately recognized. With comparable accuracy and repeatability to classical column assay in grouping 450 blood samples, the proposed approach further demonstrates to be a versatile sample-to-result platform for clinical diagnostics, food safety, and environmental monitoring.

Severe cutaneous adverse drug reactions: diagnostic approach and genetic study in a Brazilian case series

Summary

Background. Severe cutaneous adverse reactions (SCAR) are potentially fatal reactions. Genetic predisposition is involved in their pathogenesis related to drugs and ethnicities, however in a mixed population these relationships are still unknown. The aim of this study was to describe phenotypes, suspect drugs and HLA-alleles related to SCAR, identified by a systematized approach in a Brazilian case series. Methods. Patients who were diagnosed with SCAR between March 2011 and July 2019 at our university hospital were included. European Network for Drug Allergy (ENDA) questionnaire was used to collect clinical and laboratory data and algorithms for assessment of drug causality were applied. Socio-demographic variables included age, gender and skin color/ethnicity. Drug patch tests (DPT) and HLA-A, -B, -DRB1 typing were carried out. Results. A total of 74 patients were included: 36 (48.64%) with SJS/TEN, 32 (43.24%) DRESS/DIHS, 3 (4.05%) AGEP, 2 (2.70%) overlap(DRESS/SJS and DRESS/AGEP) and 1 (1.35%) GBFDE. The median age was31.5 years (IQR = 14-52.25), most were female (n = 44/59.46%) and brown (n = 38/51.35%). Anticonvulsants (n = 32/43.24%) were the largest group involved and antibiotics (n = 26/35.13%) were the second most common. Two patients with DRESS died during the acute phase. Positive DPT were shown only in anticonvulsant associated DRESS. HLA related to abacavir, allopurinol and carbamazepine were identified. Conclusions. A systematized approach allowed the phenotypic characterization of SCAR. The HLA-A*31:01, B*57:01 and B*58:01 alleles were identified, reinforcing the causality in SCAR by CBZ, ABC and ALLO in the Brazilian population.

Agreement Between Predictive, Allergen-Specific IgE Values Assessed by ImmunoCAP and IMMULITE 2000 3gAllergy™ Assay Systems for Milk and Wheat Allergies

Purpose

ImmunoCAP^® (ImmunoCAP) and IMMULITE^® 2000 3gAllergy™ (3gAllergy) systems are major quantitative allergen-specific immunoglobulin E (sIgE) assay methods. Due to the heterogeneous nature of allergenic extracts and differences in the assay format, quantitation of allergen-sIgEs is not expected to correlate well between different methods. However, we have recently reported good agreement between the methods in the diagnosis of egg allergy. This study aimed to determine and correlate the predictive values of sIgE by the two systems in the diagnosis of milk and wheat allergies.

Methods

Children who had undergone oral food challenge (OFC) for the diagnosis of milk and wheat allergies were enrolled. The OFCs were performed to diagnose either true allergy in the 1-year-old group (A) or tolerance in the 2- to 6-year-old group (B). Milk, casein and β-lactoglobulin, and wheat and ω-5 gliadin sIgE values were measured using the 2 systems. The predictive accuracy of each sIgE for the OFC outcome was assessed using receiver operating characteristic (ROC) curves. The probability of a positive OFC outcome was estimated by logistic regression analysis.

Results

A total of 395 patients were recruited from 7 primary care clinics and 19 hospitals in Japan. Milk and wheat OFCs were performed for 87 and 102 group A patients, and 124 and 82 group B patients, respectively. ROC analysis yielded similar areas under the curve for the 2 assays (0.7–0.9). The log-transformed sIgE data showed a strong linear correlation with the estimated probabilities (R > 0.9).

Conclusions

The 2 systems may be interchangeable for diagnosis of milk and wheat allergies in young children.

Graft survival effect of HLA-A allele matching parathyroid allotransplantation

Permanent hypoparathyroidism is an endocrine disease that is mostly associated with the disruption of the parathyroid glands during surgery. Allotransplantation is the most promising approach for treatment particularly for its cost-effective and exact curative potential. Herein our aim was to evaluate human leukocyte antigen (HLA)-A allele matching effect on clinical improvement and graft survival after parathyroid transplantation. We performed parathyroid transplantation between ABO/Rh compatible recipient and an unrelated donor who has chronic kidney disease. Preoperative immunological tests include panel reactive antibody, T-flow cytometry crossmatch, B-flow cytometry crossmatch, autoflow cytometry crossmatch, and complement-dependent cytotoxicity crossmatch tests were performed. After histopathological evaluation, half of the resected parathyroid gland cells were isolated and transplanted to the omentum surface by laparoscopy. The transplantation outcome was followed up throughout 382 days. The recipient discharged 2 days after transplantation without any complication. During follow-up, calcium and vitamin D supplementation reduced to a one-third dose; even the intact PTH levels remained low. However, clinical improvement was observed by serum calcium levels. The recipient still continues with low-dose supplementation after 382 days of post-transplantation. Parathyroid cell transplantation to the omental tissue is the most promising option even with only one allele matching for patients with using lifelong high-dose supplementation. Clinical improvements and long-term effect of HLA-A allele matching should be evaluated with more studies and in larger cohorts as well.

Occupational respiratory allergy to lettuce in lettuce farmers

BACKGROUND

Lettuce-associated respiratory allergy has never been reported before. The aim of this study was to clarify the clinical condition of lettuce-associated respiratory allergy and to identify the lettuce antigen which induces allergic symptoms.

METHODS

We distributed questionnaires to 1168 lettuce farmers and performed medical examinations in those who exhibited respiratory symptoms related to occupational exposure to lettuce. We analysed specific IgE-binding proteins in the sera of patients through immunoblotting analysis and determined molecular characterization of the IgE-binding bands using liquid chromatography-mass spectrometry.

RESULTS

A total of 932 farmers (80%) responded to the questionnaire. Of those, 7% exhibited lettuce-associated respiratory symptoms, during harvesting and packaging. Thirteen patients were diagnosed with allergy to lettuce and agreed to undergo further examinations. The percentage of activated basophils in these patients was significantly higher compared with that reported in negative controls (P < .05). Lettuce-specific IgE (ImmunoCAP® ) and skin prick testing was positive in 46% and 62% of patients, respectively. Notably, occupational lettuce-allergic asthma was detected in one patient through specific bronchial provocation testing. The IgE-binding bands recognized in the sera of >50% of patients were identified as epidermis-specific secreted glycoprotein EP1-like (51 kDa).

CONCLUSION

The present analysis identified a novel lettuce allergen. This allergen may have clinically useful applications, such as specific IgE testing and allergen-specific immunotherapy.

Immune response to SARS-CoV-2 and mechanisms of immunopathological changes in COVID-19

As a zoonotic disease that has already spread globally to several million human beings and possibly to domestic and wild animals, eradication of coronavirus disease 2019 (COVID-19) appears practically impossible. There is a pressing need to improve our understanding of the immunology of this disease to contain the pandemic by developing vaccines and medicines for the prevention and treatment of patients. In this review, we aim to improve our understanding on the immune response and immunopathological changes in patients linked to deteriorating clinical conditions such as cytokine storm, acute respiratory distress syndrome, autopsy findings and changes in acute-phase reactants, and serum biochemistry in COVID-19. Similar to many other viral infections, asymptomatic disease is present in a significant but currently unknown fraction of the affected individuals. In the majority of the patients, a 1-week, self-limiting viral respiratory disease typically occurs, which ends with the development of neutralizing antiviral T cell and antibody immunity. The IgM-, IgA-, and IgG-type virus-specific antibodies levels are important measurements to predict population immunity against this disease and whether cross-reactivity with other coronaviruses is taking place. High viral load during the first infection and repeated exposure to virus especially in healthcare workers can be an important factor for severity of disease. It should be noted that many aspects of severe patients are unique to COVID-19 and are rarely observed in other respiratory viral infections, such as severe lymphopenia and eosinopenia, extensive pneumonia and lung tissue damage, a cytokine storm leading to acute respiratory distress syndrome, and multiorgan failure. Lymphopenia causes a defect in antiviral and immune regulatory immunity. At the same time, a cytokine storm starts with extensive activation of cytokine-secreting cells with innate and adaptive immune mechanisms both of which contribute to a poor prognosis. Elevated levels of acute-phase reactants and lymphopenia are early predictors of high disease severity. Prevention of development to severe disease, cytokine storm, acute respiratory distress syndrome, and novel approaches to prevent their development will be main routes for future research areas. As we learn to live amidst the virus, understanding the immunology of the disease can assist in containing the pandemic and in developing vaccines and medicines to prevent and treat individual patients.

Diagnostic accuracy and safety of inhalation challenge tests for bird fancier's lung-Systematic review and meta-analysis

OBJECTIVE

To assess the diagnostic accuracy of inhalation challenge tests for bird fancier's lung and related adverse reactions.

DESIGN

We performed a systematic review and meta-analysis for the diagnostic test accuracy of inhalation challenge tests and a systematic review for adverse events of the tests. We evaluated the risk of bias and applicability of the included articles for diagnostic test accuracy with the modified Quality Assessment of Diagnostic Accuracy Studies-2 tool. We used hierarchical summary receiver operating characteristic (HSROC) curve analysis to evaluate the sensitivity and specificity of challenge tests and assessed subjective adverse reactions and steroid treatment use. Sensitivity was calculated by fixing specificity at 99% from the HSROC curve.

DATA SOURCES

We searched for articles evaluating the diagnostic accuracy of inhalation challenge tests or describing adverse reactions in Medline, Embase, the Cochrane Library, the International Clinical Trials Registry Platform, and Web of Science.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included randomized control trials, prospective or retrospective cohort studies, or case-control studies assessing the diagnostic test accuracy of inhalation challenge tests for bird fancier's lung. For adverse effects review, we included the same articles, and case series or case reports reporting adverse reactions of inhalation challenge tests.

RESULTS

In our review of 12 articles, the diagnostic accuracy of inhalation challenge tests was substantially high. Point estimate of sensitivity when calculated with a fixed specificity of 99% was 99%. Among 873 patients, 6 needed steroid treatment for adverse reactions; however, no death occurred due to acute exacerbation following a challenge test.

CONCLUSIONS

Inhalation challenges for bird fancier's lung could be accurate and safe diagnostic procedures and may be considered both as rule-in and rule-out tests in tertiary care centres. However, caution is required regarding overestimation of diagnostic yield due to risk of bias. Systematic review registration: University hospital Medical Information Network Clinical Trials Registry (UMIN000038799).

Antinuclear Antibodies With a Homogeneous and Speckled Immunofluorescence Pattern Are Associated With Lack of Cancer While Those With a Nucleolar Pattern With the Presence of Cancer

Background: Different antinuclear antibody (ANA) patterns have been associated with the presence of cancer, while other are typically seen in autoimmune diseases. This study aims to investigate the association between ANA and cancer, focusing on patients with ANA with a nucleolar indirect immunofluorescence (IIF) pattern.

Materials and Methods: ANA patterns and positivity of antibodies against nuclear antigens (NA), in particular those responsible for a nucleolar ANA pattern and/or associated with systemic sclerosis (CENP-A/B, fibrillarin, Ku, NOR-90, PM/Scl-100, PM/Scl-75, RNAP-III, Scl-70, Ro52/TRIM21, and Th/To) were analyzed and correlated to an internal database of patients with cancer.

Results: The study included 15,728 patients who had an ANA analysis, 386 patients who had immunodot analysis for antibody/ies against/to specific NA and 15,701 patients diagnosed with cancer. The presence of ANA with a nucleolar pattern showed an increased relative risk (RR 1.5, 95%CI 1.03-2.3) for an associated cancer. Anti-Scl70 and anti-RNAP-III were associated with cancer in 15 and 14%, respectively. The presence of ANA with a homogeneous & speckled (HS) pattern was significantly associated with the absence of cancer (p < 0.01). Patients with a HS pattern were found to have a lower relative risk (RR 0.7, 95%CI 0.5-0.9) of having cancer compared to those with other patterns.

Conclusions: Larger studies are needed to investigate which particular antibody/ies against/to specific NA is responsible for the association between nucleolar ANA and cancer, but anti-Scl70 and anti-RNAP-III, which is frequently associated with the presence of anti-RNAP-I, are good candidates to explain this association. Patients with a nucleolar pattern might be considered for cancer screening, in particular if they have anti-Scl70 and anti-RNAP-III antibodies.

Non-heat inactivated autologous serum increases accuracy of in vitro CFSE lymphocyte proliferation test (LPT) for nickel

Background

Skin patch testing is still seen as the gold standard for the diagnosis of allergic hypersensitivity. For several metals and for patients with a suspected adverse reaction to their medical device implant material, patch testing can be unreliable. The current alternative to metal allergy patch testing is the in vitro lymphocyte proliferation test (LPT) using tritiated thymidine. This method is well‐established but requires handling of radioactive material, often uses heat‐inactivated allogenic human pooled serum and cannot determine T cell subsets.

Objective

To develop a radioactive free LPT by using carboxyfluorescein succinimidyl ester (CFSE) and to evaluate the influence of serum source (heat‐inactivated human pooled serum [HI HPS] vs autologous serum) on the sensitivity and specificity of the nickel‐specific LPT.

Methods

Peripheral blood mononuclear cells derived from nickel‐allergic patients and healthy controls were collected, labelled with CFSE and cultured in medium containing 10% HI HPS or 10% autologous serum with or without additional T cell skewing cytokine cocktails (Th1: IL‐7/IL‐12, Th2: IL‐7/IL‐4 or Th17: IL‐7/IL‐23/IL‐1β) in the absence or presence of NiSO₄. The stimulation index (SI) was calculated as the ratio of divided cells, that is the percentage of CFSE^low/neg CD3⁺CD4⁺ T‐lymphocytes upon nickel stimulation compared to the percentage of CFSE^low/neg CD3⁺CD4⁺ T‐lymphocytes without antigen. These results were compared with the history of Ni allergy, patch test results and the MELISA test.

Results

Autologous serum positively influenced Ni‐specific proliferation while HI HPS negatively influenced Ni‐specific proliferation. The test protocol analysing CD4⁺ cells and autologous serum without skewing cytokines scored the best diagnostic values (sensitivity 95%; specificity 93%; and overall accuracy 94%) compared to the parallel test using HI HPS (accuracy 60%). Cytokine supplements did not further improve the test protocol which used autologous serum. The protocol using HI HPS could be further improved by addition of the cytokine skewing cocktails.

Conclusions

Here, we describe an optimized and highly accurate flow cytometric LPT which comprises of CFSE‐labelled cells cultured in autologous serum (not heat inactivated) and without the presence of T cell skewing cytokines.

Clinical relevance

The sensitivity and specificity of LPT is enhanced, compared to HI HPS, when autologous serum without skewing cytokines is used.

Identification of the amino-terminal fragment of Ara h 1 as a major target of the IgE-binding activity in the basic peanut protein fraction

BACKGROUND

Small, basic peanut proteins are often poorly extracted in pH-neutral buffers that are optimal for the extraction of peanut storage proteins such as Ara h 1. As a result, such proteins are easily missed as potential allergens.

OBJECTIVE

To analyse the allergenic composition of the basic peanut protein (BPP) fraction.

METHODS

A peanut extract prepared at pH 4 was fractionated by physicochemical procedures. Chemical analysis was performed by SDS-PAGE and mass spectrometry. Because immunoblotting was found to be inefficient for most of these small basic proteins, IgE-binding activity was measured by coupling the fractions to CNBr-activated Sepharose, followed by incubation with sera from 55 Dutch peanut-allergic children and ¹²⁵ I-labelled anti-IgE.

RESULTS

Most IgE reactivity of the BPP fraction was due to the 5-7 kDa amino-terminal fragment of Ara h 1. This finding was confirmed by the use of the fragment in recombinant form, to which 25/55 of the sera was IgE-positive.

CONCLUSION

The amino-terminal fragment of Ara h 1, a member of a family of small anti-microbial proteins, is an allergen independent of the carboxy-terminal fragment of Ara h 1.

Heparin-induced thrombocytopenia: An international assessment of the quality of laboratory testing

BACKGROUND

Accurate diagnosis of heparin-induced thrombocytopenia (HIT) is essential to ensure timely treatment and prevent complications. Current diagnostic assays include enzyme-linked immunosorbent assays (ELISAs) and rapid immunoassays (RIs). RIs offer fast turnaround times but were not significantly represented in previous external proficiency testing challenges.

OBJECTIVES

To use external proficiency testing to assess qualitative concordance for heparin/PF4 antibody detection.

METHODS

From 2013 to 2017, the External Quality Control for Assays and Tests (ECAT) Foundation distributed 10 samples internationally.

RESULTS

In total, 437 laboratories submitted 3149 results. ELISAs accounted for 1484 (47%) responses with RIs accounting for 1665 (53%) responses. RI use increased over the 5-year period. ELISAs classified 96% of both consensus positive and consensus negative samples concordantly. The coefficient of variation (CV) for positive sample optical densities (ODs) ranged from 35% to 50% when combining ELISA assay methods together. Quantitative RIs classified 97% of consensus-positive and 98% of consensus-negative samples concordantly. Qualitative RIs had a higher proportion of discordant responses and classified 88% of consensus-positive samples and 73% of consensus-negative samples concordantly. Of RIs only latex immunoassays and IgG specific chemiluminescent assays identified > 95% of samples concordantly with consensus.

CONCLUSION

Quantitative RIs and ELISAs classify > 95% of samples concordantly. The ODs from different ELISA methods vary considerably and are not interchangeable. Qualitative RI use is increasing despite a greater proportion of discordant classifications. This includes a higher than expected number of negative classifications for consensus-positive samples among many RIs, challenging their use as "rule out" tests.

A comparison of intradermal test with recombinant tuberculosis allergen (diaskintest) with other immunologic tests in the diagnosis of tuberculosis infection

Background

The WHO strategy for eradication of tuberculosis (TB) by 2035 (The End TB Strategy) is aimed at an early and precise diagnosis and subsequent effective treatment of TB patients. Currently, there is no gold standard for the diagnosis of latent TB infection. This study evaluated the diagnostic capabilities of a new intradermal test using recombinant TB allergen (Diaskintest) compared with tuberculin skin test (TST) and commercial TB interferon-gamma release assays (IGRAs).

Methods

A post-hoc data analysis that involved examining 860 HIV-negative, bacillus Calmette-Guérin (BCG)-vaccinated persons aged 1-65 years who visited the TB health-care institutions of Saint Petersburg to rule out or confirm an active TB was conducted from 2011 to 2016.

Results

A high degree of consistency of the Diaskintest results with the enzyme-linked immunospot and QuantiFERON-TB Gold In-Tube test (ELISPOT and QFT) results was observed in the examined pediatric population (n = 696), with a Diaskintest cutoff ≥5 mm: the kappa consistency indices were 1.000 and 0.937, for ELISPOT and QFT, respectively. A high sensitivity of Diaskintest, comparable with the IGRA tests, was observed in patients with a confirmed TB diagnosis in all age groups. The sensitivity of Diaskintest in patients of the TB/MTB + group aged 18 years and older was 88.7%; of ELISPOT, 90.6%; of QFT, 87.0%. The conducted analysis has shown a high concordance of results of the commercial TB tests in adult HIV-negative patients (n = 164) with a Diaskintest cutoff ≥5 mm: the kappa indices were 0.805 and 0.636 (Diaskintest vs. ELISPOT and QFT, respectively) among BCG-vaccinated people.

Conclusion

According to the WHO recommendations, replacing the TST by IGRAs is not recommended as a public health intervention in resource-constrained settings because the IGRA tests are more costly and technically complex to conduct than the TST. Diaskintest has comparable complexity to the TST and its performance is close to that of IGRA in a BCG-vaccinated population. Thus, our study demonstrates that replacing the TST by Diaskintest can be recommended as a public health intervention in resource-constrained and universal BCG vaccination settings.

Potential of Host Serum Protein Biomarkers in the Diagnosis of Tuberculous Meningitis in Children

Background: Tuberculous meningitis (TBM) is the most severe form of tuberculosis and results in high morbidity and mortality in children. Diagnostic delay contributes to the poor outcome. There is an urgent need for new tools for the rapid diagnosis of TBM, especially in children. Methods: We collected serum samples from children in whom TBM was suspected at a tertiary hospital in Cape Town, South Africa. Children were subsequently classified as having TBM or no TBM using a published uniform research case-definition. Using a multiplex cytokine array platform, we investigated the concentrations of serum biomarkers comprising biomarkers that were previously found to be of value in the diagnosis of adult pulmonary TB (CRP, SAA, CFH, IFN-γ, IP-10, Apo-AI, and transthyretin) plus other potentially useful host biomarkers as diagnostic candidates for TBM. Findings: Out of 47 children included in the study, 23 (48.9%) had a final diagnosis of TBM and six were HIV infected. A modified version of the adult 7-marker biosignature in which transthyretin was replaced by NCAM1, diagnosed TBM in children with AUC of 0.80 (95% CI, 0.67-0.92), sensitivity of 73.9% (95% CI, 51.6-89.8%) and specificity of 66.7% (95% CI, 44.7-84.4%), with the other six proteins in the signature (CRP, IFN-γ, IP-10, CFH, Apo-A1, and SAA) only achieving and AUC of 0.75 (95% CI, 0.61-0.90) when used in combination. A new childhood TBM specific 3-marker biosignature (adipsin, Aβ42, and IL-10) showed potential in the diagnosis of TBM, with AUC of 0.84 (95% CI, 0.73-0.96), sensitivity of 82.6% (95 CI, 61.2-95.0%) and specificity of 75.0% (95% CI, 53.3-90.2%) after leave-one-out cross validation. Conclusion: A previously described adult 7-marker serum protein biosignature showed potential in the diagnosis of TBM in children. However, a smaller childhood TBM-specific 3-marker signature demonstrated improved performance characteristics. Our data indicates that blood-based biomarkers may be useful in the diagnosis of childhood TBM and requires further validation in larger cohort studies.

Sensitization to minor cat allergen components is associated with type-2 biomarkers in young asthmatics

BACKGROUND

Cat allergy is a major trigger of asthma world-wide. Molecular patterns of cat sensitization vary between individuals, but their relationship to inflammation in asthmatics has not been extensively studied.

OBJECTIVE

To investigate the prevalence and levels of IgE antibodies against different cat allergen components and their relationship to type-2 inflammation and total IgE among young asthmatic subjects sensitized to furry animals.

METHODS

Patients with asthma (age 10-35 years; n = 266) and IgE sensitization to cat, dog or horse extract (ImmunoCAP), were analysed for IgE to the cat allergen components Fel d 1 (secretoglobin), Fel d 2 (serum albumin), Fel d 4 and Fel d 7 (lipocalins). Independent associations between IgE-antibody concentrations, and fraction of exhaled nitric oxide (FeNO), blood eosinophil (B-Eos) count, and total IgE were analysed by multiple linear regression after adjustment for possible confounders.

RESULTS

The level of IgE against Fel d 2 was independently related to FeNO (P = .012) and total IgE (P < .001), and IgE against Fel d 4 associated with Β-Eos count (P = .009) and total IgE (P < .001). IgE antibodies against Fel d 1 or cat extract did not independently relate to these inflammatory markers (P = .23-.51).

CONCLUSIONS

Levels of IgE to lipocalin (Fel d 4) and serum albumin (Fel d 2), but not to secretoglobin (Fel d 1) or cat extract, were independently associated with type-2 biomarkers and total IgE in young asthmatics.

CLINICAL RELEVANCE

We suggest that measurement of IgE to minor cat allergen components may be useful when investigating asthma morbidity in cat allergic subjects.

Cut-off values of immunological tests to identify patients at high risk of severe lupus nephritis

Cut-off values for anti-dsDNA, anti-nucleosome and anti-C1q antibodies tests and for complementmediated hemolytic activity (CH50) were explored to identify patients with high risk of developing severe lupus nephritis (LN). Forty-one patients with confirmed systemic lupus erythematosus (SLE) were identified; their levels for the three antibodies and complement had been measured on a same serum sample. These patients were classified based on the presence of renal involvem ent; sixteen had active proliferative LN. With the cut-off values accepted in the laboratory for SLE diagnosis (anti-dsDNA > 100 UI/ml, anti-nucleosome > 50 U/ml or CH50 < 190 UCH50%) no significant differences were found between patients with and without LN. Anti-C1q > 40 U/ml showed a statistically significant association with LN and had 80% of specificity. Cut-off values for LN identified by Receiver Operating Characteristic curves (ROC) were higher for anti-dsDNA (> 455 IU/ml) and antinucleosome (>107 U/ml), lower for CH50 (< 150 UCH50%) and, for anti-C1q (> 41 U/ml) coincided with the cut-off values accepted for SLE. Anti-C1q > 134 U/ml had a 92% of specificity, 56% of sensibility and was associated with a fifteen-fold increased risk of LN. The simultaneous presence of anti-nucleosome > 107 U/ml and anti-C1q > 134 U/ml was associated with a 27-fold higher probability for LN. According to these results, the cut-off values used to detect SLE activity could be inadequate to identify patients at high risk of severe LN.

Clinical evaluation of a multiparametric ELISA as a rapid tool for routinely diagnosing IgG-mediated autoimmune blistering dermatoses in ethnic Slavs

BACKGROUND

Technical innovation of autoimmune blistering dermatoses (ABDs) diagnosis aimed at multiplex approach. Two multiparametric ELISA tests are commercially available for ABDs serology. The aim was to compare diagnostic accuracy of multiparametric and monospecific ELISAs and to examine the diagnostic value/agreement of multivariant ELISA in compliance with traditional diagnostic setup for ABDs.

METHODS

In total, 128 sera from suspected ABDs patients were studied (27 sera in order to compare ELISAs). Multivariant ELISA (detection of IgG against desmoglein 1 and 3 - DSG1/3; BP180, BP230, envoplakin, type VII collagen), monovariant ELISA, and statistical analysis were performed.

RESULTS

With the use of sera from patients with suspected ABDs, the multiparametric ELISA yield an agreement of 84% with traditional stepwise diagnostics. Multivariant ELISA with BP180 and BP230 showed 87.5% and 80% sensitivity, 87.5% and 91% specificity, 87.5% reliability as well as 87.5% and 80% positive predictive value, 87.5% and 91% negative predictive value, respectively, in relation to monospecific ELISA. Multivariant ELISA with DSG1 and DSG3 showed 50% and 80% sensitivity, 100% and 80% specificity, 85% and 80% reliability as well as 100% and 57% positive predictive value, 82% and 92% negative predictive value, respectively, in relation to monospecific ELISA. A better rate of agreement was observed among ELISA systems with BP180 and BP230, than with ELISA systems with DSG1 and DSG3.

CONCLUSION

Multivariant ELISA test combined with clinical examinations and DIF is recommended as a minimal approach to diagnosing ABDs in ethnic Slavs.

Pru p 3, a marker allergen for lipid transfer protein sensitization also in Central Europe

In the Mediterranean area, lipid transfer proteins (LTPs) are important causes of plant‐food allergies often associated with severe allergic reactions. There, peach LTP (Pru p 3) seems to be the primary sensitizer, whereas in Central Europe, little is known about the importance of LTP sensitization. In this region, allergen extract‐based diagnosis is often complicated by co‐sensitization to Bet v 1, the major birch pollen allergen, its cross‐reactive food allergens, and profilins. We investigated the role of LTP sensitization in Central European patients displaying strong allergic reactions to plant‐derived food. Analysis of IgE reactivity revealed that ten of thirteen patients were sensitized to Pru p 3, nine to Bet v 1, and two to profilin. Our results showed that LTP sensitization represents a risk factor for severe allergic symptoms in Central Europe. Furthermore, the strong IgE reactivity detected in immunoblots of plant‐food extracts indicated that Pru p 3 can be used as a marker allergen for LTP sensitization also in Central European patients.

Accuracy of molecular diagnostics in pemphigus and bullous pemphigoid: comparison of commercial and modified mosaic indirect immunofluorescence tests as well as enzyme-linked immunosorbent assays

Introduction

Pemphigus and bullous pemphigoid (BP) are identified by autoantibodies (abs) against desmoglein 1, 3 (DSG1/3) and BP180/BP230, respectively. A novel mosaic to indirect immunofluorescence (IIF) using purified BP180 recombinant proteins spotted on slide and transfected cells expressing BP230, DSG1, DSG3 is available. The commercial (IgG detection) and modified (IgG4 detection) mosaic for indirect immunofluorescence (IIFc – IIF commercial, IIFm – IIF modified) and IgG ELISAs were evaluated in pemphigus and bullous pemphigoid (BP) molecular diagnostics.

Aim

To compare diagnostic accuracy of commercial (IgG detection) and modified (IgG4 detection) mosaic IIF assay and to examine the diagnostic value of ELISAs in relation to mosaic IIF in routine laboratory diagnostics of pemphigus and BP.

Material and methods

Sera from 37 BP and 19 pemphigus patients were studied. Associations between tests were assessed using Fisher’s exact test.

Results

There are associations between the positive/negative samples detected by IIFc with desmoglein1 (DSG1)/desmoglein3 (DSG3)/BP230 transfected cells and ELISAs and no association between anti-BP180 IgG detection by IIFc and ELISA. IIFm with DSG1 and DSG3 showed both 100% sensitivity and 100% and 78% specificity, respectively, and 100% and 83% positive predictive value in relation to IIFc. IIFm with BP230 had 87% specificity, 55% sensitivity, whereas IIFm with BP180 had a 100% sensitivity and 13% specificity in relation to IIFc.

Conclusions

The IIFc with DSG1/DSG3/BP230 transfected cells, excluding BP180 spots, is an alternative method to ELISA in pemphigus/BP diagnostics. IgG4 antibodies, both pathogenically and diagnostically important, are inconsistently detectable with IIFm.

Genetic predisposition to hemophagocytic lymphohistiocytosis: Report on 500 patients from the Italian registry

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening disease affecting mostly children but also adults and characterized by hyperinflammatory features. A subset of patients, referred to as having familial hemophagocytic lymphohistiocytosis (FHL), have various underlying genetic abnormalities, the frequencies of which have not been systematically determined previously.

OBJECTIVE

This work aims to further our understanding of the pathogenic bases of this rare condition based on an analysis of our 25 years of experience.

METHODS

From our registry, we have analyzed a total of 500 unselected patients with HLH.

RESULTS

Biallelic pathogenic mutations defining FHL were found in 171 (34%) patients; the proportion of FHL was much higher (64%) in patients given a diagnosis during the first year of life. Taken together, mutations of the genes PRF1 (FHL2) and UNC13D (FHL3) accounted for 70% of cases of FHL. Overall, a genetic diagnosis was possible in more than 90% of our patients with FHL. Perforin expression and the extent of degranulation have been more useful for diagnosing FHL than hemophagocytosis and the cytotoxicity assay. Of 281 (56%) patients classified as having "sporadic" HLH, 43 had monoallelic mutations in one of the FHL-defining genes. Given this gene dosage effect, FHL is not strictly recessive.

CONCLUSION

We suggest that the clinical syndrome HLH generally results from the combined effects of an exogenous trigger and genetic predisposition. Within this combination, different weights of exogenous and genetic factors account for the wide disease spectrum that ranges from HLH secondary to severe infection to FHL.

HLA class II peptide tetramers vs allergen-induced proliferation for identification of allergen-specific CD4 T cells

BACKGROUND

Fluorescence-labeled MHC class II/peptide tetramer complexes are considered as optimal tools to characterize allergen-specific CD4(+) T cells, but this technique is restricted to frequently expressed HLA class II molecules and knowledge of immunodominant epitopes. In contrast, allergen-stimulated proliferation assessed by CFSE dilution is less sophisticated and widely applicable. The major mugwort allergen, Art v 1, contains only one single, immunodominant, HLA-DR1-restricted epitope (Art v 125-36 ). Thus, essentially all Art v 1-reactive cells should be identified by a HLA-DRB1*01:01/Art v 119-36 tetramer.

METHODS

We compared specificity and sensitivity of tetramer(+) and allergen-induced proliferating (CFSE(lo) ) CD4(+) T cells by flow cytometry.

RESULTS

The frequency of tetramer(+) CD4(+) T cells determined ex vivo in PBMC of mugwort-allergic individuals ranged from 0 to 0.029%. After 2-3 weeks of in vitro expansion, sufficient tetramer(+) T cells for phenotyping were detected in 83% of Art v 125-36 -reactive T-cell lines (TCL) from mugwort-allergic individuals, but not in TCL from healthy individuals. The tetramers defined bona fide Th2 cells. Notably, Art v 125-36 -reactive TCL depleted of tetramer(+) T cells still reacted to the peptide, and only 44% of Art v 125-36 -specific T-cell clones were detected by the tetramer. CFSE(lo) CD4(+) T cells contained only 0.3-10.7% of tetramer(+) T cells and very low proportions of Th2 cells.

CONCLUSION

Allergen-specific T cells can be identified by HLA class II tetramers with high specificity, but unexpected low sensitivity. In contrast, allergen-stimulated CFSE(lo) CD4(+) T cells contain extremely high fractions of bystander cells. Therefore, for T-cell monitoring, either method should be interpreted with caution.

Standardized testing with chlorhexidine in perioperative allergy--a large single-centre evaluation

BACKGROUND

Perioperative allergic reactions to chlorhexidine are often severe and easily overlooked. Although rare, the prevalence remains unknown. Correct diagnosis is crucial, but no validated provocation model exists, and other diagnostic tests have never been evaluated. The aims were to estimate (i) the prevalence of chlorhexidine allergy in perioperative allergy and (ii) the specificity and sensitivity for diagnostic tests for chlorhexidine allergy.

METHODS

We included all patients investigated for suspected perioperative allergic reactions in the Danish Anaesthesia Allergy Centre during 2004-2012. The following tests were performed: specific IgE (Immunocap® ; Phadia AB, Sweden), histamine release test (HR) (RefLab ApS, Denmark), skin prick test (SPT) and intradermal test (IDT). Positivity criteria were as follows: specific IgE >0.35 kUA/l; HR class 1-12; SPT mean wheal diameter ≥3 mm; IDT mean wheal diameter ≥ twice the diameter of negative control. Chlorhexidine allergy was post hoc defined as a relevant clinical reaction to chlorhexidine combined with two or more positive tests. Based on this definition, sensitivity and specificity were estimated for each test.

RESULTS

In total, 22 of 228 patients (9.6%) met the definition of allergy to chlorhexidine. Estimated sensitivity and specificity were as follows: specific IgE (sensitivity 100% and specificity 97%), HR (sensitivity 55% and specificity 99%), SPT (sensitivity 95% and specificity 97%) and IDT (sensitivity 68% and specificity 100%).

CONCLUSIONS

In patients investigated for suspected perioperative allergic reactions, 9.6% were diagnosed with allergy to chlorhexidine. Using our definition of chlorhexidine allergy, the highest combined estimated sensitivity and specificity was found for specific IgE and SPT.

Olive, grass or both? Molecular diagnosis for the allergen immunotherapy selection in polysensitized pollinic patients

BACKGROUND

Grass and olive are the most frequently pollens that induce seasonal allergic rhinitis in Spain. Cross-reactivity due to panallergens shared by them and overlapping pollination complicates the recognition of allergy-causing agents, making it difficult to identify the most appropriate allergen immunotherapy (AIT) to use. The aim of this study was to determine the sensitization pattern to major grass and olive pollen allergens using component-resolved diagnostics in patients with seasonal allergic rhinitis (SAR) and positive skin prick test to grass and olive pollens and evaluate how knowledge of the sensitization patterns might influence AIT prescription.

METHODS

After informed written consent, a total of 1263 patients were recruited. A serum determination of specific IgE levels to Ole e 1 and Phl p 1 + 5 was performed to all patients. A comparison was made before and after obtaining the specific IgE results, and differences in diagnosis were stated.

RESULTS

At the 0.35 kU/l cut-off point, 71.2% of patients were positive to Ole e 1 and Phl p 1 + 5, 14% were positive only to Phl p 1 + 5 and 12% were positive only to Ole e 1. Based on available clinical data and skin prick test results, 922 (73%) patients would have been indicated for a mixture of grass and olive pollens for AIT. In 56.8% of patients, there was non-coincidence in the composition of AIT that would be selected before and after investigators received the in vitro data.

CONCLUSION

The diagnostic accuracy of the recombinant allergen-specific IgE test could help to improve the selection of specific-allergen immunotherapy in polysensitized patients.

Estimated Prevalence of Tuberculosis Infection Among a New York City Clinic Population Using Interferon-gamma Release Assays

Using QuantiFERON®-Gold In-Tube (QFT-GIT) data, the prevalence of tuberculosis infection in New York City was estimated. Patient characteristics associated with a positive result were consistent with known tuberculosis risk factors. Results suggest that blood-based tests for tuberculosis infection are reliable.

Background

 Elimination of tuberculosis (TB) in the United States requires treating not only persons with active disease but also those infected with TB. Achieving this goal requires understanding local TB infection prevalence and identifying subgroups at increased risk for infection and disease.

Methods

 The study population included all patients tested with an interferon-gamma release assay (IGRA) test at New York City (NYC) public TB clinics from October 1, 2006 to December 31, 2011. Patients who were not a case or contact at testing (general clinic patients) and who had a positive QuantiFERON-Gold In-Tube (QFT-GIT) test result were compared with those with indeterminate or negative results to identify characteristics associated with positive results. New York City TB surveillance data were used to identify clinic patients later diagnosed with active TB disease.

Results

 A total of 69 273 IGRA tests were conducted. Among 20 066 patients tested with QFT-GIT, 16% tested positive, 83% tested negative, and <1% were indeterminate. Of 18 481 general clinic patients, 14% had a positive QFT-GIT result. Nine percent of United States-born patients compared with 19% of foreign-born patients had a positive result. Increasing age and birth in a high-incidence country were associated with a higher likelihood of having a positive result. One patient with a negative QFT-GIT result was identified as a TB case 2 years later.

Conclusions

 Using QFT-GIT data, the background prevalence of TB infection in NYC was estimated. Patient characteristics associated with a positive QFT-GIT result were consistent with known TB risk factors. Results suggest that IGRAs are reliable tests for TB infection.