Could the IgA isotype provide additional information in systemic sclerosis patients? A retrospective study entailing IgA isotyping in a Mediterranean systemic sclerosis cohort.

OBJECTIVES: Anti-CENP-B (ACA), anti-topoisomerase I (ATA) and anti-RNA polymerase III (RP3) autoantibodies are included in the 2013 SSc-ACR/EULAR classification criteria. The detection of additional autoantibodies is of interest when those are negative. Additionally, we wonder if the IgA isotype might play a role in SSc. The aims of the study were to assess the prevalence of ACA, ATA, RP3, and Ro52 autoantibodies of IgG and IgA isotype and to describe their association with clinical manifestations in a cohort of patients with SSc. METHODS: Samples from 97 patients with SSc fulfilling the 2013 ACR/EULAR classification criteria, and 50 blood donors were included and tested for IgA and IgG isotypes of ACA, ATA, RP3, and Ro52 by FEIA. RESULTS: The prevalence of IgG+IgA isotypes for the same specificity was 62.5%, 82.6%, 80.0%, 36.8%, for ACA, ATA, RP3 and Ro52, respectively. Isolated IgG was present in 35.4%, 13.0%, 20.0% and 42.1% of patients for ACA, ATA, RP3 and Ro52, respectively. Only six patients were isolated IgA for a unique specificity. Clinically, ILD tended to be associated with ATA-IgG and ATA-IgG+IgA, telangiectasias with ACA-IgG+IgA and arthritis with ACA-IgA. Indeed, digital ulcers were more frequent in ATA-IgG patients. CONCLUSIONS: Most of the patients presented ACA, ATA, or RP3 autoantibodies of IgA isotype in addition to IgG. Regarding clinical relevance, Ro52-IgG+IgA and ACA-IgG had a tendency towards sineSSc phenotype, while ACA-IgG+IgA to lcSSc phenotype. Thus, if confirmed, the determination of ACA-IgA could provide a tool to stratify patients according to the cutaneous phenotype.

Alternative to In Vivo Tests During the COVID-19 Pandemic: Multiple Allergen Simultaneous Tests as a Useful First Screening.

BACKGROUND: In allergy diagnosis we sometimes find some clinical or logistic limitations to be able to carry out in vivo tests, so the detection of serum allergic-specific IgE could be an alternative as a first screening step. Here, we compare the results from the routine diagnostic tools and multiple allergen simultaneous tests to detect inhalant allergen sensitization. METHODS: Thirty-two subjects with a positive ImmunoCAP Phadiatop screening were included, evaluating the accuracy of their diagnosis using (1) specific IgE determination by ImmunoCAP and (2) MAST EUROLINE Immunoblot. RESULTS: The MAST method showed a high agreement and correlation with the ImmunoCAP system for Derma-tophagoides pteronyssinus, cat dander, orchard grass and Alternaria alternata. Of the subjects, 94% were sensitized to at least one of the allergens using MAST EUROLINE immunoblot, whereas 79% of individuals with a positive Phadiatop went undetected when we analyzed only the 4 allergens mentioned before. CONCLUSIONS: The study showed the usefulness of MAST EUROLINE immunoblot for screening detection of specific IgE antibodies directed against a broad spectrum of inhalant allergens as a first screening tool. Furthermore, its performance is not affected by the possible in vivo test limitations and avoids the arbitrary selection of allergenic sources for evaluation, which may lead to incorrect patients' diagnosis and management.

Performance of basophil activation test and specific IgG4 as diagnostic tools in nonspecific lipid transfer protein allergy: Antwerp-Barcelona comparison.

BACKGROUND: Recent studies show that nsLTP sensitization is not limited to the Mediterranean basin and can present diverse clinical phenotypes. It remains challenging to predict clinical outcome when specific IgE antibodies (sIgE) to nsLTPs are present. This study compares both clinical and in vitro allergy characteristics but also diagnostic performance of a basophil activation test (BAT) and sIgG4 in nsLTP-sensitized patients from Antwerp (ANT, Belgium) and Barcelona (BCN, Spain). METHODS: Adult subjects with positive sIgE rPru p 3 and/or rMal d 3 ≥ 0.10 kUA /L (n = 182) and healthy controls (n = 37) were included. NsLTP-sensitized individuals were stratified according to clinical symptoms with peach/apple, respectively. BAT rPru p 3 and rMal d 3 were performed and sIgG4 antibodies to both components quantified. RESULTS: In BCN, only ratios of sIgG4/sIgE rMal d 3 and BAT rMal d 3 (0.001 µg/mL) can identify clinically relevant Mal d 3 sensitization (sensitivity of 60%-63% and a specificity of 75%-67%, respectively). In ANT, only the sIgE/total IgE rPru p 3 ratio shows added value (sensitivity 60% and specificity 83%). Finally, it appears that symptomatic patients in BCN are more sensitive to lower allergen concentrations compared to ANT. In addition, it was shown that ANT patients were more often sensitized to pollen and that specific pollen sources differed between regions. CONCLUSIONS: NsLTP-related allergy profiles and diagnostic performance differ significantly between regions and are component-specific, which makes extrapolation of data difficult to do. In addition, it seems that basophil sensitivity might show geographical differences. Additional research is needed to confirm these findings.

Low Levels Matter: Clinical Relevance of Low Pru p 3 sIgE in Patients With Peach Allergy.

Many clinical lab settings still use 0.35 KUA/L as the cut-off for serum specific-IgE (sIgE) immunoassays, while the detection limit is 0.1 KUA/L. The clinical relevance of -low-level sIgE (0.1-0.35 KUA/L) remains controversial. Pru p 3 sIgE is considered to be the main routine tool for assessing lipid transfer protein (LTP) sensitization. We aimed to evaluate the clinical relevance of Pru p 3 sIgE low levels in a population diagnosed with LTP allergy. Adults diagnosed with LTP allergy and Pru p 3 sIgE ≥ 0.1 KUA/L between 2012 and 2019 were included. Clinical data were reviewed. nPru p 3 basophil activation test (BAT) was performed and basophil reactivity (BR) and sensitivity (BS) correlated with the peach allergy symptoms. Pru p 3 sIgE from 496 subjects was recorded, 114 (23.0%) between 0.1 and 0.34 KUA/L (grLOW), the rest ≥ 0.35 KUA/L (grB). A total of 44.7% in grLOW and 59.9% in grB were allergic. Urticaria was more frequent in grLOW. In grLOW, Pru p 3 sIgE was higher in patients with local compared with systemic symptoms. In grB, Pru p 3 sIgE was higher in allergic patients. Pru p 3/Total IgE ratios were higher in allergic vs. tolerant in both groups. In BAT, BR was similar in both groups. In grLOW, it was higher on allergic compared with tolerant (p = 0.0286), and on those having systemic vs. local symptoms (p = 0.0286). BS showed no significant difference between groups. Patients with low levels represent a non-negligible fraction and around 45% are peach allergic. BAT showed functional sIgE in them. Pru p 3 sensitizations should be carefully evaluated even when sIgE levels are low.

CoVITEST: A Fast and Reliable Method to Monitor Anti-SARS-CoV-2 Specific T Cells From Whole Blood.

Cellular and humoral immune responses are essential for COVID-19 recovery and protection against SARS-CoV-2 reinfection. To date, the evaluation of SARS-CoV-2 immune protection has mainly focused on antibody detection, generally disregarding the cellular response, or placing it in a secondary position. This phenomenon may be explained by the complex nature of the assays needed to analyze cellular immunity compared with the technically simple and automated detection of antibodies. Nevertheless, a large body of evidence supports the relevance of the T cell's role in protection against SARS-CoV-2, especially in vulnerable individuals with a weakened immune system (such as the population over 65 and patients with immunodeficiencies). Here we propose to use CoVITEST (Covid19 anti-Viral Immunity based on T cells for Evaluation in a Simple Test), a fast, affordable and accessible in-house assay that, together with a diagnostic matrix, allows us to determine those patients who might be protected with SARS-CoV-2-reactive T cells. The method was established using healthy SARS-CoV-2-naïve donors pre- and post-vaccination (n=30), and further validated with convalescent COVID-19 donors (n=51) in a side-by-side comparison with the gold standard IFN-γ ELISpot. We demonstrated that our CoVITEST presented reliable and comparable results to those obtained with the ELISpot technique in a considerably shorter time (less than 8 hours). In conclusion, we present a simple but reliable assay to determine cellular immunity against SARS-CoV-2 that can be used routinely during this pandemic to monitor the immune status in vulnerable patients and thereby adjust their therapeutic approaches. This method might indeed help to optimize and improve decision-making protocols for re-vaccination against SARS-CoV-2, at least for some population subsets.

Immunological Changes in Blood of Newborns Exposed to Anti-TNF-α during Pregnancy.

BACKGROUND: Although anti-TNF-α monoclonal antibodies are considered safe during pregnancy, there are no studies on the development of the exposed-infant immune system. The objective was to study for the first time the impact of throughout pregnancy exposure to anti-TNF-α has an impact in the development of the infant's immune system, especially B cells and the IL-12/IFN-γ pathway. METHODS: Prospective study of infants born to mothers with inflammatory bowel disease treated throughout pregnancy with anti-TNF-α (adalimumab/infliximab). Infants were monitored both clinically and immunologically at birth and at 3, 6, 12, and 18 months. RESULTS: We included seven patients and eight healthy controls. Exposed infants had detectable levels of anti-TNF-α until 6 months of age; they presented a more immature B- and helper T-phenotype that normalized within 12 months, with normal immunoglobulin production and vaccine responses. A decreased Treg cell frequency at birth that inversely correlated with mother's peripartum anti-TNF-α levels was observed. Also, a decreased response after mycobacterial challenge was noted. Clinically, no serious infections occurred during follow-up. Four of seven had atopia. CONCLUSION: This study reveals changes in the immune system of infants exposed during pregnancy to anti-TNF-α. We hypothesize that a Treg decrease might facilitate hypersensitivity and that defects in IL-12/IFN-γ pathway might place the infant at risk of intracellular infections. Pediatricians should be aware of these changes. Although new studies are needed to confirm these results, our findings are especially relevant in view of a likely increase in the use of these drugs during pregnancy in the coming years.