Gluten-Free Diet Adherence Tools for Individuals with Celiac Disease: A Systematic Review and Meta-Analysis of Tools Compared to Laboratory Tests.

This systematic review aimed to find the tool that best predicts celiac individuals' adherence to a gluten-free diet (GFD). The Transparent Reporting of Multivariable Prediction Models for Individual Prognosis or Diagnosis (TRIPOD-SRMA) guideline was used for the construction and collection of data from eight scientific databases (PubMed, EMBASE, LILACS, Web of Science, LIVIVO, SCOPUS, Google Scholar, and Proquest) on 16 November 2023. The inclusion criteria were studies involving individuals with celiac disease (CD) who were over 18 years old and on a GFD for at least six months, using a questionnaire to predict adherence to a GFD, and comparing it with laboratory tests (serological tests, gluten immunogenic peptide-GIP, or biopsy). Review articles, book chapters, and studies without sufficient data were excluded. The Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modeling Studies (CHARMS) was used for data collection from the selected primary studies, and their risk of bias and quality was assessed using the Prediction Risk of Bias Assessment Tool (PROBAST). The association between the GFD adherence determined by the tool and laboratory test was assessed using the phi contingency coefficient. The studies included in this review used four different tools to evaluate GFD adherence: BIAGI score, Coeliac Dietary Adherence Test (CDAT), self-report questions, and interviews. The comparison method most often used was biopsy (n = 19; 59.3%), followed by serology (n = 14; 43.7%) and gluten immunogenic peptides (GIPs) (n = 4; 12.5%). There were no significant differences between the interview, self-report, and BIAGI tools used to evaluate GFD adherence. These tools were better associated with GFD adherence than the CDAT. Considering their cost, application time, and prediction capacity, the self-report and BIAGI were the preferred tools for evaluating GFD adherence.

Safety of CoronaVac and ChAdOx1 vaccines against SARS-CoV-2 in patients with rheumatoid arthritis: data from the Brazilian multicentric study safer.

BACKGROUND: Patients with immune-mediated rheumatic diseases (IMRDs) have been prioritized for COVID-19 vaccination to mitigate the infection severity risks. Patients with rheumatoid arthritis (RA) are at a high risk of severe COVID-19 outcomes, especially those under immunosuppression or with associated comorbidities. However, few studies have assessed the safety of the COVID-19 vaccine in patients with RA. OBJECTIVE: To evaluate the safety of vaccines against SARS-CoV-2 in patients with RA. METHODS: This data are from the study "Safety and Efficacy on COVID-19 Vaccine in Rheumatic Diseases," a Brazilian multicentric prospective phase IV study to evaluate COVID-19 vaccine in IMRDs in Brazil. Adverse events (AEs) in patients with RA of all centers were assessed after two doses of ChAdOx1 (Oxford/AstraZeneca) or CoronaVac (Sinovac/Butantan). Stratification of postvaccination AEs was performed using a diary, filled out daily and returned at the end of 28 days for each dose. RESULTS: A total of 188 patients with RA were include, 90% female. CoronaVac was used in 109 patients and ChAdOx1 in 79. Only mild AEs were observed, mainly after the first dose. The most common AEs after the first dose were pain at the injection (46,7%), headache (39,4%), arthralgia (39,4%), myalgia (30,5%) and fatigue (26,6%), and ChAdOx1 had a higher frequency of pain at the injection (66% vs 32 %, p < 0.001) arthralgia (62% vs 22%, p < 0.001) and myalgia (45% vs 20%, p < 0.001) compared to CoronaVac. The more common AEs after the second dose were pain at the injection (37%), arthralgia (31%), myalgia (23%), headache (21%) and fatigue (18%). Arthralgia (41,4% vs 25%, p = 0.02) and pain at injection (51,4% vs 27%, p = 0.001) were more common with ChAdOx1. No serious AEs were related. With Regard to RA activity level, no significant difference was observed between the three time periods for both COVID-19 vaccines. CONCLUSION: In the comparison between the two immunizers in patients with RA, local reactions and musculoskeletal symptoms were more frequent with ChAdOx1 than with CoronaVac, especially after the first dose. In summary, the AE occurred mainly after the first dose, and were mild, like previous data from others immunizing agents in patients with rheumatoid arthritis. Vaccination did not worsen the degree of disease activity.

Salmonid Rickettsial Septicemia (SRS) disease dynamics and Atlantic salmon immune response to Piscirickettsia salmonis LF-89 and EM-90 co-infection.

In Chile, Piscirickettsia salmonis contains two genetically isolated genogroups, LF-89 and EM-90. However, the impact of a potential co-infection with these two variants on Salmonid Rickettsial Septicemia (SRS) in Atlantic salmon (Salmo salar) remains largely unexplored. In our study, we evaluated the effect of P. salmonis LF-89-like and EM-90-like co-infection on post-smolt Atlantic salmon after an intraperitoneal challenge to compare changes in disease dynamics and host immune response. Co-infected fish had a significantly lower survival rate (24.1%) at 21 days post-challenge (dpc), compared with EM-90-like single-infected fish (40.3%). In contrast, all the LF-89-like single-infected fish survived. In addition, co-infected fish presented a higher presence of clinical lesions than any of the single-infected fish. The gene expression of salmon immune-related biomarkers evaluated in the head kidney, spleen, and liver showed that the EM-90-like isolate and the co-infection induced the up-regulation of cytokines (e.g., il-1ß, ifnγ, il8, il10), antimicrobial peptides (hepdicin) and pattern recognition receptors (PRRs), such as TLR5s. Furthermore, in serum samples from EM-90-like and co-infected fish, an increase in the total IgM level was observed. Interestingly, specific IgM against P. salmonis showed greater detection of EM-90-like antigens in LF-89-like infected fish serum (cross-reaction). These data provide evidence that P. salmonis LF-89-like and EM-90-like interactions can modulate SRS disease dynamics in Atlantic salmon, causing a synergistic effect that increases the severity of the disease and the mortality rate of the fish. Overall, this study contributes to achieving a better understanding of P. salmonis population dynamics.

Identification of differentially expressed genes, pathways, and immune infiltration in diabetes.

This study aimed to perform exhaustive bioinformatic analysis by using GSE29221 micro-array maps obtained from healthy controls and Type 2 Diabetes (T2DM) patients. Raw data are downloaded from the Gene Expression Omnibus database and processed by the limma package in R software to identify Differentially Expressed Genes (DEGs). Gene ontology functional analysis and Kyoto Gene Encyclopedia and Genome Pathway analysis are performed to determine the biological functions and pathways of DEGs. A protein interaction network is constructed using the STRING database and Cytoscape software to identify key genes. Finally, immune infiltration analysis is performed using the Cibersort method. This study has implications for understanding the underlying molecular mechanism of T2DM and provides potential targets for further research.

CD4+ and CD8+ T-cell multi-epitope chimeric protein associated with an MPLA adjuvant induce protective efficacy and long-term immunological memory for the immunoprophylaxis of American Tegumentary Leishmaniasis.

American Tegumentary Leishmaniasis (ATL) is a disease of high severity and incidence in Brazil, in addition to being a worldwide concern in public health. Leishmania amazonensis is one of the etiological agents of ATL, and the inefficiency of control measures, associated with the high toxicity of the treatment and the lack of effective immunoprophylactic strategies, makes the development of vaccines indispensable and imminent. In this light, the present study proposes to elaborate a chimeric protein (rChiP), based on the fusion of multiple epitopes of CD4+/CD8+ T cells, identified in the immunoproteome of the parasites L. amazonensis and L. braziliensis. The designed chimeric protein was tested in the L. amazonensis murine model of infection using the following formulations: 25 µg of the rChiP in saline (rChiP group) and 25 µg of the rChiP plus 25 µg of MPLA-PHAD® (rChiP+MPLA group). After completing immunization, CD4+ and CD8+ T cells, stimulated with SLa-Antigen or rChiP, showed an increased production of nitric oxide and intracytoplasmic pro-inflammatory cytokines, in addition to the generation of central and effector memory T cells. rChiP and rChiP+MPLA formulations were able to promote an effective protection against L. amazonensis infection determined by a reduction in the development of skin lesions and lower parasitic burden. Reduction in the development of skin lesions and lower parasitic burden in the vaccinated groups were associated with an increase of nitrite, CD4+/CD8+IFN-γ+TNF-α+ and CD4+/CD8+CD44highCD62Lhigh/low T cells, IgGTotal, IgG2a, and lower rates of IgG1 and CD4+/CD8+IL-10+. This data suggests that proposed formulations could be considered potential tools to prevent ATL.

Biosocial Technical Systems: An Emerging Approach to Analyse Responses to Novel Diseases.

The COVID-19 pandemic emerged in the context of a parallel epidemic of information, namely an infodemic. With the development of vaccines occurring in record time, a disinformation campaign ensued rendering the infodemic ever more troubling. As COVID-19 had to be curbed with vaccines opinion pools and surveys indicated that a minority, but relevant, part of the general public had weakened trust in public health policies and also on governmental responses to the pandemic in general. This dissent in public opinion on pandemic response is interpreted in this chapter as a controversy related to the efficacy and risks associated to vaccines. Such controversy gained momentum partly because traditional scientific communication has been largely unidirectional rather than bi-directional. We propose to apply a novel biosocial technical perspective to examine the COVID-19 pandemic controversy and communication, articulating social, biological and technical issues. The interaction between COVID-19 and vaccines, i.e. artefact-biological interactions, resulted in vaccine development in record time. However, the interaction between social systems and vaccine as artefacts was plagued by partial public reluctance in their acceptance. This rendered communication efforts ever more relevant, bringing lessons related to the importance of a more fluid bi-directional communication in future disease epidemics.

The effectiveness of early systemic inflammatory indices in predicting advanced intraventricular hemorrhage in preterm infants.

Some systemic inflammatory indices have been reported to be associated with intracerebral hemorrhage in adults. However, the relationship between systemic inflammatory indices and intraventricular hemorrhage (IVH) in premature neonates is still not completely understood. OBJECTIVE: To evaluate the relationship between systemic inflammatory indices obtained on the first day of life in premature infants and the development of severe IVH. PATIENTS AND METHOD: Premature newborns < 32 weeks of gestational age were included. Eligible patients were divided into 2 groups: Group 1: without IVH or grade I and II hemorrhage, and Group 2: grade III and IV HIV. Demographic characteristics, clinical outcomes, monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune inflammation index (SII), pan-immune inflammation value (PIV), and Systemic inflammation response index (SIRI) were compared between groups. RESULTS: A total of 1176 newborns were included in the study, 1074 in Group 1 and 102 premature babies in Group 2. There was no difference between the groups in terms of the count of leukocytes, neutrophils, monocytes, lymphocytes and platelets (p > 0.05). The values of NLR, MLR, PLR, PIV, SII and SIRI were similar in both groups (p > 0.05). CONCLUSION: While the relationship between inflammation, hemodynamics and IVH is still under discussion, our results show that systemic inflammatory indices have no predictive value for IVH.

Higher risk of upper respiratory tract infection post marathon running: when physical exercise becomes a threat to the immune system.

Background: Several studies have reported that marathon runners have a higher risk of upper respiratory tract infections (URTI) post marathon than non-exercising controls. However, other studies did not find a higher risk of URTI in the same participants before and after a marathon, precluding a conclusive consensus. Besides the between-subjects effects, another important confounding factor in these results is the different pre and post follow-up time to track URTI. Objectives: Identify by meta-analysis whether a marathon Running increases the risk of URTI, adjusting the follow-up time to track URTI. Data sources: We searched for articles using MEDLINE (PubMed), Embase, Scopus, Web of Science, the Cochrane Library, and EBSCOhost, combining the marathon and respiratory infection descriptor synonyms, on 1st December 2022. Eligibility criteria: The PICOS framework included human population, comparison between pre and post marathon running, of URTI symptoms (assessed from one to 4 weeks), in noncontrolled intervention studies. Data Synthesis: Because follow-up was longer before the marathon in many studies, we adjusted the number of subjects with infections before marathon to the equivalent post-marathon follow-up duration. There was 18% higher incidence of URTI post-marathon (OR 1.18 95%CI [1.05-1.33], p= 0.005) in a very consistent meta-analysis (I2 = 0%, p = 0.69), with no risk of publication bias (Egger test p-value = 0.82) for the 7 studies included. The main issues with quality of the studies were bias in measuring the outcome, bias in classification of intervention (participation in the marathon) and time-varying confounding (corrected for analysis), and therefore the quality of evidence was moderate (GRADE approach = 3). Limitations: The need for follow-up time adjustment is a limitation, since the number of URTI recorded could be different if the original studies had used the same follow-up time pre and post marathon. The subjectivity of the URTI assessments is another limitation in this field. Conclusions: There is an increased risk of URTI post marathon running and research on this topic to understand mechanisms might support runners to find efficient interventions to reduce this risk. Protocol: Protocol registration on in the International Prospective Register of Systematic Reviews (PROSPERO): CRD42022380991.

Description of BCG and Tuberculosis Disease in a Cohort of 79 Patients with Chronic Granulomatous Disease.

PURPOSE: Chronic granulomatous disease (CGD) is an inherited immunodeficiency caused by pathogenic variants of genes encoding the enzyme complex NADPH oxidase. In countries where tuberculosis (TB) is endemic and the Bacillus Calmette-Guérin (BCG) vaccine is routinely administered, mycobacteria are major disease-causing pathogens in CGD. However, information on the clinical evolution and treatment of mycobacterial diseases in patients with CGD is limited. The present study describes the adverse reactions to BCG and TB in Mexican patients with CGD. METHODS: Patients with CGD who were evaluated at the Immunodeficiency Laboratory of the National Institute of Pediatrics between 2013 and 2024 were included. Medical records were reviewed to determine the clinical course and treatment of adverse reactions to BCG and TB disease. RESULTS: A total of 79 patients with CGD were included in this study. Adverse reactions to BCG were reported in 55 (72%) of 76 patients who received the vaccine. Tuberculosis was diagnosed in 19 (24%) patients. Relapse was documented in three (10%) of 31 patients with BGC-osis and six (32%) of 19 patients with TB, despite antituberculosis treatment. There was no difference in the frequency of BCG and TB disease between patients with pathogenic variants of the X-linked CYBB gene versus recessive variants. CONCLUSIONS: This report highlights the importance of considering TB in endemic areas and BCG complications in children with CGD to enable appropriate diagnostic and therapeutic approaches to improve prognosis and reduce the risk of relapse.

Immune reconstitution in rheumatic disease patients after autologous hematopoietic stem cell transplantation.

High-dose conditioning chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT) in systemic sclerosis (SSc), lupus erythematosus (SLE), juvenile idiopathic arthritis (JIA), or rheumatoid arthritis (RA) was shown to allow eradication of the abnormal autoimmune compartment and "resetting" of the immune response, all contributing to the observed clinical response. A subset of patients has less favorable clinical outcomes after transplant, as auto-reactive memory cells may escape depletion or the regulatory immune network renewal be incomplete. Conditioning permits non-specific abrogation of the autoreactive T- and B-cell responses and eliminates the autoimmune repertoire. Re-infusion of autologous hematopoietic stem cells shortens the leucopenia duration and contributes to both hematologic and immune reconstitutions. After engraftment and neutrophil recovery, the first phase of immune reconstitution is characterized by clonal expansion of residual memory lymphocytes in response to early antigen stimulation and/or lymphopenia-induced proliferation. Renewal of the immune repertoire follows through exportation of de novo generated thymic-derived naïve T cells and bone marrow-derived naïve B cells, expansion of the regulatory network, and a shift from a pro-inflammatory to a more auto-tolerant profile. We review the well-described mechanisms of immune resetting and their relative contribution to disease control according to the transplantation regimen and the underlying rheumatic diseases.

Macrophages directly kill bladder cancer cells through TNF signaling as an early response to BCG therapy.

The Bacillus Calmette-Guérin (BCG) vaccine is the oldest cancer immunotherapeutic agent in use. Despite its effectiveness, its initial mechanisms of action remain largely unknown. Here, we elucidate the earliest cellular mechanisms involved in BCG-induced tumor clearance. We developed a fast preclinical in vivo assay to visualize in real time and at single-cell resolution the initial interactions among bladder cancer cells, BCG and innate immunity using the zebrafish xenograft model. We show that BCG induced the recruitment and polarization of macrophages towards a pro-inflammatory phenotype, accompanied by induction of the inflammatory cytokines tnfa, il1b and il6 in the tumor microenvironment. Macrophages directly induced apoptosis of human cancer cells through zebrafish TNF signaling. Macrophages were crucial for this response as their depletion completely abrogated the BCG-induced phenotype. Contrary to the general concept that macrophage anti-tumoral activities mostly rely on stimulating an effective adaptive response, we demonstrate that macrophages alone can induce tumor apoptosis and clearance. Thus, our results revealed an additional step to the BCG-induced tumor immunity model, while providing proof-of-concept experiments demonstrating the potential of this unique model to test innate immunomodulators.

Contribution of memory T cells to the generation of long-lasting immunity against COVID-19.

Humans are exposed every day to innumerable external stimuli, both environmental and microbial. Immunological memory recalls each specific stimulus and mounts a secondary response that is faster and of a larger magnitude than the primary response; this process constitutes the basis for vaccine development. The COVID-19 pandemic offers a unique opportunity to study the development of immune memory against an emergent microorganism. Memory T cells have an important role in the resolution of COVID-19, and they are key pillars of immunological memory. In this review, we summarize the main findings regarding anti-SARS-CoV-2 memory T cells after infection, after vaccination, and after the combination of these two events ("hybrid immunity"), and analyze how these cells can contribute to long-term protection against the infection with SARS-CoV-2 variants.

Los humanos se exponen cada día a innumerables estímulos externos, tanto ambientales como microbianos. La memoria inmunológica registra de manera específica un estímulo y articula una respuesta secundaria más rápida y de mayor magnitud que la respuesta primaria; este proceso constituye la base del desarrollo de vacunas. La pandemia de COVID-19 ofreció la oportunidad de estudiar el desarrollo de la memoria inmunológica contra un microorganismo emergente. Las células T de memoria tienen un papel importante en la resolución de COVID-19 y son pilares importantes de la memoria inmunológica. En esta revisión se resumen los principales hallazgos de la respuesta de las células T de memoria contra la infección por SARS-CoV-2, a la vacunación o a la combinación de ambos procesos ("inmunidad híbrida"), y se discute cómo estas células pueden contribuir a la protección a largo plazo contra distintas variantes del virus.

Prevalence and factors associated with hepatitis B susceptibility among men who sex with men on HIV pre-exposure prophylaxis in Northeastern Brazil: a cross-sectional study.

BACKGROUND: This study aimed to determine the prevalence and factors associated with susceptibility to hepatitis B virus (HBV) among cisgender men who have sex with men (MSM) on HIV pre-exposure prophylaxis (PrEP) in Northeastern Brazil. METHODS: This was a cross-sectional, analytical study conducted between September 2021 and June 2023. Participants underwent structured interviews to collect sociodemographic and clinical information, including hepatitis B vaccination history, HIV PrEP use and sexual health history. Blood samples were collected for hepatitis B serologic testing: HBV surface antigen (HBsAg), HBV surface antibody (anti-HBs), total and IgM HBV core antibody (anti-HBc). HBV susceptibility was defined as nonreactive results for all these serological markers. RESULTS: A total of 287 participants were enrolled into the study. The median age of the individuals was 31 years (interquartile range: 27; 36). HBV susceptibility was found in 58 out 286 individuals (20.3%; 95% CI: 15.9-25.2). Seventy-six percent of the participants reported completing the three-dose hepatitis B vaccine schedule. Susceptibility was significantly associated with a monthly income ≤ 5 minimum wages (PR: 2.02; 95% CI: 1.01-4.05), lack of complete hepatitis B vaccination schedule (PR: 4.52; 95% CI: 2.89-7.06), initiation of HIV PrEP (PR: 2.18; 95% CI: 1.21-3.94), duration of six months of HIV PrEP (PR: 2.16; 95% CI: 1.19-3.91), absence of tattoos (PR: 1.55; 95% CI: 1.00-2.40) and no history of sexually transmitted infections (PR: 1.65; 95% CI: 1.07-2.54). CONCLUSION: Our findings highlight the significant burden of HBV susceptibility among MSM on HIV PrEP in Northeastern Brazil. Socioeconomic factors, vaccination status, PrEP use and sexual health behaviors play critical roles in determining susceptibility to HBV. Integrating hepatitis B screening and vaccination into PrEP services is critical for identifying and addressing HBV susceptibility among MSM. Interventions aimed at increasing vaccination coverage and promoting safer sexual practices are essential for mitigating the burden of HBV infection in this population.

Tumor-Suppressive Cross-Linking of Anti-T. cruzi Antibodies in Acute Lymphoblastic Leukemia.

Parasites have been associated with possible anticancer activity, including Trypanosoma cruzi, which has been linked to inhibiting the growth of solid tumors. To better understand this antitumor effect, we investigated the association of anti-T. cruzi antibodies with B cells of the acute lymphoblastic leukemia (ALL) SUPB15 cell line. The antibodies were generated in rabbits. IgGs were purified by affinity chromatography. Two procedures (flow cytometry (CF) and Western blot(WB)) were employed to recognize anti-T. cruzi antibodies on SUPB15 cells. We also used CF to determine whether the anti-T. cruzi antibodies could suppress SUPB15 cells. The anti-T. cruzi antibodies recognized 35.5% of the surface antigens of SUPB15. The complement-dependent cytotoxicity (CDC) results demonstrate the cross-suppression of anti-T. cruzi antibodies on up to 8.4% of SUPB15 cells. For the WB analysis, a band at 100 kDa with high intensity was sequenced using mass spectrometry, identifying the protein as nucleolin. This protein may play a role in the antitumor effect on T. cruzi. The anti-T. cruzi antibodies represent promising polyclonal antibodies that have the effect of tumor-suppressive cross-linking on cancer cells, which should be further investigated.

α-IRAK-4 Suppresses the Activation of RANK/RANKL Pathway on Macrophages Exposed to Endodontic Microorganisms.

Periapical lesions are common pathologies affecting the alveolar bone, often initiated by intraradicular lesions resulting from microbial exposure to dental pulp. These microorganisms trigger inflammatory and immune responses. When endodontic treatment fails to eliminate the infection, periapical lesions persist, leading to bone loss. The RANK/RANKL/OPG pathway plays a crucial role in both the formation and the destruction of the bone. In this study, the objective was to inhibit the RANK/RANKL pathway in vitro within exposed Thp-1 macrophages to endodontic microorganisms, specifically Enterococcus faecalis, which was isolated from root canals of 20 patients with endodontic secondary/persistent infection, symptomatic and asymptomatic, and utilizing an α-IRAK-4 inhibitor, we introduced endodontic microorganisms and/or lipoteichoic acid from Streptococcus spp. to cellular cultures in a culture plate, containing thp-1 cells and/or PBMC from patients with apical periodontitis. Subsequently, we assessed the percentages of RANK+, RANKL+, and OPG+ cells through flow cytometry and measured the levels of several inflammatory cytokines (IL-1ß, TNF-α, IL-6, IL-8, IL-10, and IL-12p70) in the cellular culture supernatant through a CBA kit and performed analysis by flow cytometry. A significant difference was observed in the percentages of RANK+RANKL+, OPG+ RANKL+ cells in thp-1 cells and PBMCs from patients with apical periodontitis. The findings revealed significant differences in the percentages of the evaluated cells, highlighting the novel role of the IRAK-4 inhibitor in addressing this oral pathology, apical periodontitis, where bone destruction is observed.

Single-cell transcriptomic analysis of B cells reveals new insights into atypical memory B cells in COVID-19.

Here, we performed single-cell RNA sequencing of S1 and receptor binding domain protein-specific B cells from convalescent COVID-19 patients with different clinical manifestations. This study aimed to evaluate the role and developmental pathway of atypical memory B cells (MBCs) in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The results revealed a proinflammatory signature across B cell subsets associated with disease severity, as evidenced by the upregulation of genes such as GADD45B, MAP3K8, and NFKBIA in critical and severe individuals. Furthermore, the analysis of atypical MBCs suggested a developmental pathway similar to that of conventional MBCs through germinal centers, as indicated by the expression of several genes involved in germinal center processes, including CXCR4, CXCR5, BCL2, and MYC. Additionally, the upregulation of genes characteristic of the immune response in COVID-19, such as ZFP36 and DUSP1, suggested that the differentiation and activation of atypical MBCs may be influenced by exposure to SARS-CoV-2 and that these genes may contribute to the immune response for COVID-19 recovery. Our study contributes to a better understanding of atypical MBCs in COVID-19 and the role of other B cell subsets across different clinical manifestations.

Calcium-dependent HLA-DQ epitope revealed by EDTA mediated inhibition of antibody reactions in the Luminex single antigen bead assay.

Complement mediated interference with the detection of antibodies targeting HLA is a known limitation of the single antigen bead (SAB) Luminex assay. Ethylenediaminetetraacetic acid (EDTA) is currently the serum treatment of choice in most histocompatibility laboratories to block complement activation by chelating calcium. The purpose of this study was to investigate a serum with an antibody reactivity to HLA-DQ6, 7, 8 and 9 molecules, in the Luminex SAB assay, that was inhibited by treatment with EDTA. Serum was from a 55-year-old highly sensitised female renal transplant candidate that contained, among others, antibodies to an epitope containing the 74EL eplet, shared by HLA-DQ6, DQ7, DQ8 and DQ9 molecules. Serum samples were treated with EDTA, dithiothreitol (DTT), or heat prior to testing by SAB assay. EDTA-treated serum was also tested after the addition of calcium chloride (CaCl2). HLA-DQ-specific antibodies were isolated by adsorption/elution method using three informative donor cells and were tested in the absence or presence of EDTA. The antibody reactivity against HLA-DQ6, DQ7, DQ8 and DQ9 in the SAB assay was significantly inhibited by treating serum and eluates with EDTA and was restored by addition of CaCl2. The study represents the first description of a calcium-dependent epitope in HLA molecules. The relevance of this finding is that the treatment of sera with EDTA could lead to false-negative reactions in the SAB assay, which may compromise virtual crossmatching.