Diagnostic Accuracy of SARS-CoV-2 Rapid Antigen Testing in a Pediatric Population: Children are Not Little Adults.

BACKGROUND: Information on the use of antigen-based SARS-CoV-2 rapid antigen tests (RAT) in children is limited. RATs have been used more frequently, because they are easily applicable, inexpensive, and can be easily performed at home without the need for special equipment. This study was designed to assign the diagnostic test accuracy of the SARS-CoV-2 RAT in daily clinical practice in children. METHODS: One thousand forty-two pediatric patients (aged 1 month - 18 years) who presented to the pediatric COVID-19 outpatient clinic of our hospital between January 2021 and June 2022 and met the inclusion criteria were included in this study. Nasopharyngeal samples were taken from the patients at the same visit, first for reverse transcription polymerase chain reaction (RT-PCR) and then for RAT. RESULTS: The data of all patients with RT-PCR positivity (n = 314) and additionally 14 patients with RAT positivity were analyzed in depth. The overall sensitivity and specificity were 62.1% (95% CI: 56.4 - 67.4) and 98% (95% CI: 96.7 - 98.9), respectively. The positive predictive value (PPV) and the negative predictive value (NPV) in this pediatric study were 93.3% and 85.7% (95% CI: 88.7 - 96.1 and 83.1 - 87.9), respectively. Considering the Ct values, which are indirect indicators of viral load, it was observed that the sensitivity of the rapid antigen test increased at low Ct values. The sensitivity increased to 75.1% (95% CI: 67.9 - 81.1) in patients with a Ct value of < 25. The specificity was 92.7% (95% CI: 90.7 - 94.3), PPV was 67.8% (95% CI: 60.7 - 67.8) and the NPV was 94.7% (95% CI: 93.0 - 96.1) in patients with a Ct value < 25. When the patients were evaluated according to their symptomatic/asymptomatic status, the difference between the diagnostic performance of the RAT test was found to be statistically significant (p = 0.006). CONCLUSIONS: In our study, it was found that the sensitivity of RATs in pediatric patients was lower than in adults. Our results also showed that children are not small adults, and the sensitivity of the test was higher, especially in symptomatic patients and patients with high viral load. To obtain more accurate results, we believe that performing the test in the first 3 days of symptoms will give more accurate results.

Localized Immunomodulation with PD-L1 Results in Sustained Survival and Function of Allogeneic Islets without Chronic Immunosuppression.

Allogeneic islet transplantation is limited by adverse effects of chronic immunosuppression used to control rejection. The programmed cell death 1 pathway as an important immune checkpoint has the potential to obviate the need for chronic immunosuppression. We generated an oligomeric form of programmed cell death 1 ligand chimeric with core streptavidin (SA-PDL1) that inhibited the T effector cell response to alloantigens and converted T conventional cells into CD4+Foxp3+ T regulatory cells. The SA-PDL1 protein was effectively displayed on the surface of biotinylated mouse islets without a negative impact islet viability and insulin secretion. Transplantation of SA-PDL1-engineered islet grafts with a short course of rapamycin regimen resulted in sustained graft survival and function in >90% of allogeneic recipients over a 100-d observation period. Long-term survival was associated with increased levels of intragraft transcripts for innate and adaptive immune regulatory factors, including IDO-1, arginase-1, Foxp3, TGF-ß, IL-10, and decreased levels of proinflammatory T-bet, IL-1ß, TNF-α, and IFN-γ as assessed on day 3 posttransplantation. T cells of long-term graft recipients generated a proliferative response to donor Ags at a similar magnitude to T cells of naive animals, suggestive of the localized nature of tolerance. Immunohistochemical analyses showed intense peri-islet infiltration of T regulatory cells in long-term grafts and systemic depletion of this cell population resulted in prompt rejection. The transient display of SA-PDL1 protein on the surface of islets serves as a practical means of localized immunomodulation that accomplishes sustained graft survival in the absence of chronic immunosuppression with potential clinical implications.

Levels of lymphocyte-associated regulators of complement system CD55 and CD59 are changed in schizophrenia patients.

OBJECTIVE: Although pathological mechanisms of schizophrenia are unknown, evidence in the literature suggests that the immune system might be involved in the pathogenesis. Complement is an important part of the immune system and it has been suggested to play role in the pathogenesis of schizophrenia. We aimed to investigate the potential involvement of the complement system in schizophrenia by the determination of peripheral concentrations of certain complement proteins and their regulators in patients. METHODS: Plasma concentrations of complement C3, C4, and C1 inhibitory protein were measured by chemiluminescence in 41 schizophrenia patients and 39 healthy controls. Expression of CD55, CD59, and CD46 proteins on peripheral blood mononuclear cells were determined by flow cytometry in the same groups. RESULTS: Frequencies of peripheral immune cells expressing CD55 were determined to be significantly higher in schizophrenia patients than in healthy people (p = 0.020). Frequencies of peripheral immune cells expressing CD59 was determined to be significantly higher in healthy people than in schizophrenia patients (p = 0.012). The expression level of CD55 per cell was measured to be significantly elevated in patients compared to healthy controls (p = 0.026). CONCLUSIONS: Our data clearly demonstrate an elevated complement activity in schizophrenia and points to a possible complement association in the pathogenesis.Key pointsIncreased the expression level, and frequency of CD55 in schizophrenia patients.Decreased frequency of CD59 in schizophrenia patients.No difference in the expression level of CD59; the expression level, and frequency of CD46; frequency of complement C3, C4, and C1 inhibitory protein.

Evaluation of QuantiFERON tuberculosis Gold In-Tube assay for diagnosis of active tuberculosis in children.

AIM: Tuberculin skin test (TST) is still used in diagnostic algorithms of childhood tuberculosis (TB). QuantiFERON TB Gold In-Tube assay (QFT-GIT) is an alternative test to TST based on the detection of interferon-gamma release upon in vitro induction of peripheral mononuclear cells by TB antigens. In this study, we aimed to determine the diagnostic value and performance of QFT-GIT for active childhood TB. METHODS: This retrospective study was conducted between January 2005 and December 2011 in three referral hospitals in Turkey with 124 children who were diagnosed with definite active TB. Sensitivity values of TST and QFT-GIT were determined by accepting the microbiological confirmation as the gold standard of diagnosis of TB. RESULTS: In our study, sensitivity of QFT-GIT and TST was found to be 65 and 66% respectively. However, combined usage of QFT-GIT and TST was found to be more sensitive (85%) than TST or QFT-GIT alone (P < 0.0001). Although negative results of QFT-GIT or TST did not exclude the diagnosis of active TB in children, their positivity supported the diagnosis. Specificity could not be measured as only microbiologically confirmed cases of Mycobacterium tuberculosis disease were enrolled in the study. CONCLUSION: Although sensitivities of TST and QFT-GIT are too low to exclude active TB, their positivity supports diagnosis of active TB in children concomitant with signs and symptoms. QFT-GIT and TST should be used together to enhance diagnostic sensitivity and could help exclude a diagnosis of TB if the pretest probability is low.

Evaluation of Samples with DFS Staining Pattern Detected by Indirect Immunofluorescence Assay.

BACKGROUND: In this study, we aimed to determine the presence of anti DFS70 antibody by a specific IB method in samples showing the DFS pattern and to determine the distribution of DFS pattern in different patient groups. METHODS: 2,401 serum samples, which were received for ANA screening, were tested by IIF method at Akdeniz University Hospital Diagnostic Laboratory. Out of 139 samples with DFS pattern, 75 samples were tested for the presence of anti DFS70 antibody by IB and were included in the study. Patients' clinical diagnoses were obtained retrospectively from medical records. RESULTS: 63 (84%) of 75 samples, which showed DFS patern by IIF, were found to have anti DFS70 antibody by IB. Five of these patients were diagnosed with SARD while the rest (58) had diseases other than SARD. CONCLUSIONS: DFS pattern detected by IIF and isolated anti DFS70 antibody positivity detected by IB show high concordance. However IIF results should be confirmed because of the patterns that can be misidentified as DFS pattern. The presence of anti-DFS70 antibodies, which help to exclude SARD, prevent further unnecessary referral demands.

Retrospective evaluation of "Rods and Rings" pattern detected in the anti-nuclear antibody (ANA) indirect immunofluorescence (IIF) test.

Introduction: Anti-rods and rings (anti-RR) antibodies have recently been described as a cytoplasmic pattern in IIF-based screening of autoantibodies on HEp-2 cells and ICAP has named it as AC-23. It is most frequently related to drug-induced antibody generation. This study aimed to investigate the clinical significance of AC-23 positivity and its relevance to the diagnosis and/or follow-up of the associated diseases and/or drug use. Methods: A multicenter retrospective study was conducted among 10 hospitals from six different provinces in Türkiye from January 2017 to December 2021. The laboratory data and clinical information of 600 patients with positive anti-RR antibodies out of 547.558 HEp-2 IIF ANA samples were analyzed. Results: The distribution of AC-23 positive patients by year indicated a steady increase between 2017-2021. Anti-RR prevalence in post-COVID-19 period was significantly higher than that of pre-COVID-19 period (p=0.00). Concomitant ANA positivity was detected in 56.5% of patients, the most common patterns being AC-4 and AC-5 (41.1%). The most frequent pathology among the anti-RR positive patients was an autoimmune disease (19.83%); 28.57% of which had rheumatoid arthritis and 17.65% autoimmune liver disease. Among the 600 patients, 65 (10.83%) were diagnosed as hepatitis C virus (HCV) infection. Available data for 38 of the HCV patients revealed that 71.05% of them had a history of interferon alfa+ribavirin and 28.95% of them had a history of NS3/4/5A/5B polymerase inhibitor or protease inhibitor drug use. Significant increase in the rate of anti-RR positivity was observed in the post-COVID-19 period when compared to pre-COVID-19 period (p:0.00). Discussion: This is the first multicenter study in Türkiye about the clinical association of anti-RR antibodies which may be ignored during routine HEp-2 IIF testing. Pathologies other than HCV should be taken into consideration in terms of the possible role of anti-RR in autoimmune diseases and other pathologies. The preliminary data obtained in this study suggest that anti-RR antibody development might also be associated to COVID-19, supporting the several previous data related to the potential of viruses triggering the formation of autoantibodies. Large-scale prospective studies should elucidate the clinical significance of RR pattern and determine its role in patient diagnosis and follow-up.

Automatic Classification of Antinuclear Antibody Patterns With Machine Learning.

Antinuclear antibodies (ANA) are important diagnostic markers in many autoimmune rheumatological diseases. The indirect immunofluorescence assay applied on human epithelial cells generates images that are used in the detection of ANA. The classification of these images for different ANA patterns requires human experts. It is time-consuming and subjective as different experts may label the same image differently. Therefore, there is an interest in machine learning-based automatic classification of ANA patterns. In our study, to build an application for the automatic classification of ANA patterns, we construct a dataset and learn a deep neural network with a transfer learning approach. We show that even in the existence of a limited number of labeled data, high accuracies can be achieved on the unseen test samples. Our study shows that deep learning-based software can be built for this task to save expert time.

An Investigation of the Relationship Between Isolated Anti-dense Fine-Speckled 70 Autoantibodies and Allergen-Specific Immunoglobulin E.

Background Although the mechanisms of the formation of anti-dense fine-speckled 70 (anti-DFS70) antibodies are not fully known, there is evidence in the literature that allergic reactions may play a role in their formation. Immunoglobulin E (IgE)-mediated immunopathological mechanisms are increasingly being elucidated in diseases such as atopic dermatitis and urticaria-related diseases. We aimed to reveal its relationship with anti-DFS70 in allergen-sensitive patients with positive specific IgE (sIgE) levels. Methodology The study included samples of 758 patients who underwent antinuclear antibody (ANA) screening and allergen-sIgE testing between January 2019 and January 2022. Patients' clinical diagnoses were retrospectively obtained from the hospital information management system. ANA was tested according to the instructions of the manufacturer by the indirect immunofluorescent antibody method using HEp-2 cell substrates (Euroimmun Luebeck, Germany). Allergen-sIgE was determined by chemiluminescence on the Immulite 2000 XPI system (Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany) according to the instructions of the manufacturer. Results ANA pattern was detected in 74 samples included in the study. ANA-positive patients were divided into DFS70 (+) and DFS70 (-) groups. A statistically significant increase in the DFS70 pattern was observed in patients with a positive allergen-sIgE test (p < 0.0001). Both allergen-sIgE and DFS70 positivity were statistically significant in younger age groups (p < 0.05). The most common diagnosis was urticaria-related conditions in 23 (31%) patients with a positive allergy test. Conclusions Our study shows that the positivity of the DFS70 pattern is increased in allergen-sensitive patients. Therefore, the allergen-sIgE-mediated allergic disease should be considered in patients with isolated anti-DSF70. Studies with related disease groups are needed to determine whether there is a relationship between anti-DFS70 and allergy-related disease in these patients. If an immunopathological mechanism is not found, these false-positive results can be considered clinically insignificant, and unnecessary consultations can be avoided.

Spontaneous remission of chronic lymphocytic leucemia in a patient with SARS-CoV2.

Although novel therapies have improved the treatment outcome of patients, chronic lymphocytic leukaemia (CLL) is still considered incurable. Recently, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), causing coronavirus disease 2019 (Covid 19), emerged in late 2019, and it has posed a global health threat. In a limited number of cases, it has been shown that some lymphoma types spontaneously regress after SARS-CoV2 infection suggesting that the infection can trigger de immune system against the tumour cell. Cross-reactivity of pathogen-specific T cells with tumour antigens and natural killer cell activation can be the possible mechanism of this hypothesis.

Serum soluble urokinase-type plasminogen activator receptor and interferon-γ-induced protein 10 levels correlate with significant fibrosis in chronic hepatitis B.

BACKGROUND: Hepatitis B virus (HBV) presents an important public health problem. Liver biopsy is currently the gold standard for assessing the degree of intrahepatic inflammation and for staging liver fibrosis. However, the value of liver biopsies is limited by sampling errors, understaging and interobserver variability in interpretation. There is, therefore, a need to identify novel, non-invasive serologic biomarkers for the development of new predictive models of fibrosis. METHODS: We enrolled patients with chronic hepatitis B infection (CHB) and examined the relationships between serum soluble urokinase plasminogen activator receptor (suPAR) and interferon-induced protein-10 (IP-10), and the results of liver biopsies. Healthy volunteers with normal aminotransferase levels and negative serological results for HBV, hepatitis C virus and human immunodeficiency virus were recruited as controls. RESULTS: Mean platelet volume, serum suPAR and IP-10 were significantly elevated in patients with CHB compared with controls. Median serum suPAR and IP-10 levels were significantly higher in patients with liver fibrosis compared with patients with mild fibrosis. There was no significant difference in mean platelet volume or aspartate aminotransferase-to-platelet ratio index scores between patients with mild and significant fibrosis. CONCLUSION: suPAR and IP-10 were able to distinguish between significant and mild fibrosis with good sensitivity and specificity, and may thus represent useful biomarkers for identifying patients with significant fibrosis.