Basophil Activation Test identifies the patients with Chronic Spontaneous Urticaria suffering the most active disease

Relevance of the basophil activation test in a cohort of 240 patients with chronic spontaneous urticaria

BACKGROUND

The basophil activation test (BAT) is considered to be the best biomarker to predict autoimmune chronic spontaneous urticaria (aiCSU). To date, few studies have investigated the utility of BAT in real-world clinical practice, the role of aiCSU biomarkers in relation to omalizumab therapy and the degree of association between different aiCSU tests.

OBJECTIVES

To analyse the clinical and laboratory features of a prospective cohort with chronic spontaneous urticaria (CSU) according to their BAT status, as well as to study omalizumab efficacy according to aiCSU biomarkers.

METHODS

A prospective study was conducted from 2010 to 2024 in patients with CSU. BAT alongside other laboratory tests were performed, and clinical and therapeutic features were prospectively collected. Data obtained were compared according to BAT status (positive vs. negative). Furthermore, omalizumab drug survival was typified according to aiCSU biomarkers.

RESULTS

In total, 240 patients were included in the study. Patients who were BAT positive presented more frequently with low IgE levels, higher occurrence of IgG antithyroid peroxidase (anti-TPO) positivity, autologous serum skin test (ASST) positivity, basopenia and eosinopenia. Multivariate logistic regression revealed that ASST [odds ratio (OR) 7.69, 95% confidence interval (CI) 2.81-21.0] and anti-TPO (OR 2.63, 95% CI 1.05-6.61) were associated with BAT positivity. All aiCSU biomarkers (BAT, ASST, combined ASST/BAT positivity and low IgE/anti-TPO+) were associated with significantly shorter omalizumab survival because of treatment failure. In the cohort, both low IgE/anti-TPO+ and ASST were associated with BAT positivity.

CONCLUSIONS

The use of BAT in clinical practice delineates a subgroup of patients with specific clinical, laboratory and therapeutic features, including increased omalizumab failure.

Flow cytometry-based basophil and mast cell activation tests in allergology: State of the art

The major challenge in allergy diagnosis is development of accessible and reliable diagnostics that can predict the clinical outcome following exposure to culprit allergen(s) or cross-reactive molecules and identification of safer alternatives than the current state-of-the-art methods. There is accumulating evidence that flow-based analyses for the quantification of activated basophils and mast cells subsequent to in vitro challenge (the basophil and mast cell activation test [BAT/MAT] or basophil activation test [BAT] and mast cell activation test [MAT]) could meet the diagnostic requirements for IgE-dependent allergies, drug hypersensitivities, and subsets of autoimmune urticaria. Furthermore, the BAT and MAT have found application in research and other nondiagnostic fields. However, appropriate use of the BAT and MAT requires understanding of the diversity of the source materials used and degranulation metrics to ensure correct test performance and interpretation of results. In this review, we provide the main applications and limitations of the BAT and MAT, as performed thus far.

Applications of basophil activation test in paediatric allergic diseases

Basophilic granulocytes, containing and releasing histamine after a specific allergy stimulation, are directly involved in IgE-mediated allergic reactions. CD63 is a transmembrane protein of secretory lysosomes of basophils and its upregulation is related with the release of histamine to the extracellular space during IgE-mediated allergic reactions. Basophil activation test (BAT) measures the activation of circulating basophils upon the in vitro stimulation of living blood cells with specific allergens. Such a test is particularly safe and reproducible and has recently emerged as a new promising diagnostic tool for allergic diseases. BAT can be used to diagnose food allergy and represents a promising alternative to oral food challenge tests, especially in children as it is less invasive, safer, and cheaper than the gold standard tests. As a biomarker of tolerance and reactivity, it is also useful to monitor natural resolution and clinical response to immune-modulatory treatments. Regarding drug allergies, BAT is even the only possible applicable diagnostic tool for allergy reactions to some drugs, because of the lack of alternative test, or given that those commonly used are unreliable, or equivocal. Additionally, BAT allows to screen patients with more active urticarial and identify Hymenoptera-allergic patients with negative venom-specific immunoglobulin (Ig)E. In respiratory allergic diseases, BAT can facilitate the diagnosis of local allergic rhinitis and evaluate basophil allergen sensitivity in allergic asthma. Although IgE-sensitization in allergic asthma is usually demonstrated by skin prick test and specific IgE, those tests do not predict the clinical allergy contribution to asthma pathogenesis. To date, the potential of BAT in the diagnostic work-up of allergic diseases is well established, but a better standardization of its use is needed. This narrative review summarizes the state-of-the-art BAT technology and applications in pediatric allergic diseases, focusing on immune-related mechanisms and the BAT real clinical utility.

Peripheral blood T-cell modulation by omalizumab in chronic urticaria patients

Background

Chronic spontaneous urticaria (CSU) is a highly prevalent and difficult to manage cutaneous disease characterized by the presence of recurrent urticaria, angioedema, or both, for a period of 6 weeks or longer. One of the biological treatments used for patients with CSU with an autoimmune background and bad control of the disease is omalizumab, an anti-IgE monoclonal antibody. The understanding of the mechanism of action of this biological drug in CSU along with the identification of potential biomarkers of clinical response can be helpful in the personalized management of the disease.

Objective

The purpose of this study was to analyze the effect of omalizumab on peripheral blood lymphocyte subpopulations in patients with CSU in order to identify potential biomarkers of treatment response.

Methods

We analyzed 71 patients with CSU [33 under omalizumab and 38 under non-immunomodulatory drugs (treated with antihistamines; NID)] and 50 healthy controls. An exhaustive immunophenotyping of whole blood T-cell subpopulations, including naïve, central memory, effector memory, effector cells, Th1, Th2, and Th17 was performed by multiparametric flow cytometry. Moreover, in CSU patients, we analyzed markers of inflammation (ESR, DD, CRP), atopy (prick test, IgE quantification), and autoimmunity (anti-thyroid antibodies and indirect basophil activation test).To evaluate the clinical activity, the Urticaria Activity Score 7 (UAS 7) test was used.

Results

In patients with CSU under treatment with omalizumab, there was a significant decrease in the percentage of naïve and an increase in the percentage of central memory CD4 T cells as well as a decrease in the percentage of naïve and increase in the percentage of effector CD8 T-cell subsets. Moreover, patients under treatment with omalizumab had higher percentages of Th1 and Th2 cells than patients under treatment with NID.

Conclusion

The immune monitoring of T-cell subpopulations in patients with CSU starting omalizumab, may be a useful strategy to analyze treatment response in the clinical practice.

PD-BAT: A novel approach of pooling basophil donors for expansion of commercial laboratory testing of Chronic Spontaneous Urticaria

The type II autoimmune subtype of Chronic Spontaneous Urticaria (CSU) is characterized by the presence of IgG autoantibodies targeting IgE or the IgE high-affinity receptor (FcεRI) on mast cells and basophils. In evaluation of CSU patients, indirect basophil activation testing (BAT), has been utilized, involving the mixing of patient serum with heterologous peripheral blood donors, followed by flow cytometric assessment of basophil markers. However, the reliability of the indirect BAT results hinges on the quality of the donor basophils utilized. In this study, we introduce an innovative approach where multiple potential basophil donors undergo rigorous BAT characterization alongside control samples. By selecting and pooling donors with optimal performance, we significantly enhance the inter-assay reproducibility of the indirect BAT test.

Autoimmune Diseases and Low Baseline IgE in Chronic Spontaneous Urticaria: A Clinical and Therapeutic Prospective Analysis in Real-Life Clinical Practice

BACKGROUND

Autoimmunity contributes to the pathogenesis of chronic spontaneous urticaria (CSU). The subtyping of CSU has revealed an autoimmune form of CSU. Despite autoimmune diseases having been associated with CSU, there are few prospective studies that have evaluated the characteristics and biomarkers of patients with CSU and autoimmune disease in a real-life practice setting.

OBJECTIVE

To evaluate the presence of specific biomarkers for the presence of autoimmune disease in CSU and to analyze the clinical and therapeutic features of patients with CSU and autoimmune disease.

METHODS

The clinical, laboratory, and therapeutic features of patients with CSU at a tertiary-level center were prospectively collected. Data obtained were compared in function of the presence/absence of autoimmune disease and typified according to IgE levels.

RESULTS

Patients with CSU who had associated autoimmune disease corresponded to middle-aged women with a common pattern of blood test findings: both low baseline IgE and high-affinity receptor of IgE expression, basopenia, eosinopenia, higher baseline erythrocyte sedimentation rate and D-dimer, increased presence of antinuclear antibodies, IgG against thyroid peroxidase, and positive autologous serum skin test result. Total baseline IgE less than or equal to 43.8 IU/mL was both the optimal cutoff to predict autoimmune disease in the CSU cohort and a significant risk factor for the presence of autoimmune disease in the regression analysis.

CONCLUSIONS

In real-life clinical practice, characteristics of patients with CSU and autoimmune disease share common features with type IIb autoimmune CSU. Total baseline IgE less than or equal to 43.8 IU/mL has been detected as a possible biomarker of autoimmune disease in patients with CSU.

Recent updates in urticaria

Urticaria is a skin-condition characterized by sudden-onset pruritic wheals with/without angioedema. Urticaria can be acute or chronic. Chronic urticaria may be spontaneous or inducible, based on absence/presence of specific triggers. Chronic spontaneous urticaria is most frequent (∼80%). Urticaria is primarily a mast-cell mediated histaminergic-disorder. Recently, other inflammatory cells and pro-inflammatory cytokines have been implicated. Deeper understanding has unmasked two endotypes - IgE-mediated type I autoimmunity/autoallergy and IgG-mediated type IIb autoimmunity. Current treatment recommendation involving second-generation H1-antihistamines, omalizumab and cyclosporine is effective in 60-80% patients. So, newer treatment options are being explored based on emerging targets. Despite being non-lethal, urticaria considerably impairs patient's quality-of-life and may be associated with extra-cutaneous comorbidities. Several "patient reported outcome measures" have been proposed to evaluate disease-activity, impact and control, for effective treatment modulation till complete disease control. This review discusses the current understanding about urticaria and its future directions, to facilitate optimum evidenced-based care.

Promises and Remaining Challenges for Further Integration of Basophil Activation Test in Allergy-Related Research and Clinical Practice

More than 20 years after having been initially proposed, the relevance and usefulness of basophil activation test (BAT) for the field of allergy research and testing were demonstrated on many occasions. Leveraging the fully open format of a flexible, whole blood-based functional assay, BAT has been shown to be equally important for fundamental research, clinical research, and diagnosis. Regardless of whether the focus of a study is on the characterization of the allergenic moiety, on the patient side, or on the study of the fundamental processes involved in the allergic disease or its treatment, BAT enables the gathering of very important insights. In spite of this, its full capabilities have yet to be leveraged. Various bottlenecks, including but not limited to assay logistics, robustness, flow cytometry access, and/or expertise, have indeed been limiting its development beyond experts and long-term users. Now, various initiatives, aiming at resolving these bottlenecks, have been launched. If successful, a broader use of BAT could then be contemplated. In such a situation, its more thorough integration in clinical practice has the potential to significantly change the allergic patient's journey.

Positive Basophil Tests Are Linked to High Disease Activity and Other Features of Autoimmune Chronic Spontaneous Urticaria: A Systematic Review

BACKGROUND

Chronic spontaneous urticaria (CSU) is believed to be Autoimmune (aiCSU) (type IIb CSU) in at least 8% of patients, associated with mast cell-activating IgG autoantibodies. Basophil tests such as the basophil activation test (BAT) and basophil histamine release assay (BHRA) are considered the best single tests for an aiCSU diagnosis. To date, the strength of associations among a positive BAT and/or BHRA (BAT/BHRA+) and CSU features, patient demographics, and response to treatment remains poorly characterized.

OBJECTIVE

To evaluate the strength of current evidence on basophil tests as parameters for CSU characteristics.

METHODS

We performed a systematic literature search and review to assess the relationship between BAT/BHRA+ and clinical and laboratory parameters of CSU. Of 1,058 records found in the search, 94 studies were reviewed by experts in urticaria and 42 were included in the analysis.

RESULTS

In CSU patients, BAT/BHRA+ showed a strong level of evidence for an association with high disease activity and low levels of total IgE. A weak level of evidence was shown for the association of BAT/BHRA+ and the presence of angioedema, and basopenia.

CONCLUSIONS

Our results suggest that aiCSU defined by BAT/BHRA+ is more active or severe and is linked to other aiCSU markers such as low total IgE/basopenia. Basophil tests should be standardized and implemented in routine clinical care to improve the diagnosis and treatment of patients with aiCSU.

Characteristics of immune response profile in patients with immediate allergic and autoimmune urticarial reactions induced by SARS-CoV-2 vaccines

Severe allergic reactions following SARS-COV-2 vaccination are generally rare, but the reactions are increasingly reported. Some patients may develop prolonged urticarial reactions following SARS-COV-2 vaccination. Herein, we investigated the risk factors and immune mechanisms for patients with SARS-COV-2 vaccines-induced immediate allergy and chronic urticaria (CU). We prospectively recruited and analyzed 129 patients with SARS-COV-2 vaccine-induced immediate allergic and urticarial reactions as well as 115 SARS-COV-2 vaccines-tolerant individuals from multiple medical centers during 2021-2022. The clinical manifestations included acute urticaria, anaphylaxis, and delayed to chronic urticaria developed after SARS-COV-2 vaccinations. The serum levels of histamine, IL-2, IL-4, IL-6, IL-8, IL-17 A, TARC, and PARC were significantly elevated in allergic patients comparing to tolerant subjects (P-values = 4.5 × 10^-5-0.039). Ex vivo basophil revealed that basophils from allergic patients could be significantly activated by SARS-COV-2 vaccine excipients (polyethylene glycol 2000 and polysorbate 80) or spike protein (P-values from 3.5 × 10^-4 to 0.043). Further BAT study stimulated by patients' autoserum showed positive in 81.3% of patients with CU induced by SARS-COV-2 vaccination (P = 4.2 × 10^-13), and the reactions could be attenuated by anti-IgE antibody. Autoantibodies screening also identified the significantly increased of IgE-anti-IL-24, IgG-anti-FcεRI, IgG-anti-thyroid peroxidase (TPO), and IgG-anti-thyroid-related proteins in SARS-COV-2 vaccines-induced CU patients comparing to SARS-COV-2 vaccines-tolerant controls (P-values = 4.6 × 10^-10-0.048). Some patients with SARS-COV-2 vaccines-induced recalcitrant CU patients could be successfully treated with anti-IgE therapy. In conclusion, our results revealed that multiple vaccine components, inflammatory cytokines, and autoreactive IgG/IgE antibodies contribute to SARS-COV-2 vaccine-induced immediate allergic and autoimmune urticarial reactions.

Association between serological indicators of past contacts with Herpesviridae and a slower resolution of chronic spontaneous urticaria in children

AIM

To evaluate the relationship between serological indicators of Herpesviridae infection and evolution of symptoms in children with chronic spontaneous urticaria (CSU).

METHODS

In this observational study, consecutive children with CSU underwent, at presentation, clinical and laboratory work-up, autologous serum skin test (ASST) to identify autoimmune urticaria (CAU), disease severity assessment (urticaria activity score 7, UAS7), serological diagnostics for Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpes virus-6 (HHV-6), and parvovirus B19, as well as for Mycoplasma pneumoniae and Chlamydia pneumoniae. Children were re-assessed at 1, 6, and 12 months after the commencement of antihistamine/antileukotriene treatment.

RESULTS

None of the 56 included children had an acute CMV/EBV or HHV-6 infection, but 17 (30.3%) had IgG antibodies against CMV, EBV, or HHV-6 (five were also seropositive for parvovirus B19); 24 (42.8%) suffered from CAU; and 9 (16.1%) were seropositive for Mycoplasma/Chlamydia pneumoniae. The initial symptom severity was moderate-to-severe (UAS7 quartiles 18-32) and comparable between Herpesviridae-seropositive and Herpesviridae-seronegative patients. At 1, 6, and 12 months, UAS7 was consistently higher in seropositive children. In a multivariable analysis (adjusted for age, baseline UAS7, ASST, mean platelet volume, and other serology), Herpesviridae seropositivity was associated with higher UAS scores: mean difference 4.2 score points (95% confidence interval 0.5-7.9; Bayes estimate 4.2, 95% credible interval 1.2-7.3) in a mixed model for repeated measures. This estimate was comparable between children with positive (CAU) and negative (CSU) ASST.

CONCLUSION

A history of CMV/EBV/HHV-6 infection might contribute to a slower-resolving CSU in children.

Basophil activation test for allergic and febrile non-haemolytic transfusion reactions among paediatric patients with haematological or oncological disease

BACKGROUND AND OBJECTIVES

Allergic transfusion reactions (ATRs) and febrile non-haemolytic transfusion reactions (FNHTRs) are common, although their mechanisms remain unclear. Immunoglobulin E (IgE)-mediated type I hypersensitivity may be involved in the pathogenesis of ATR. A basophil activation test (BAT) may help elucidate this process.

MATERIALS AND METHODS

The BAT was based on peripheral blood samples from paediatric patients with a haematological or oncological disease and on samples of residual blood products transfused in each case. Dasatinib was used to evaluate whether basophil activation was mediated by an IgE-dependent pathway.

RESULTS

Twenty-seven patients with and 19 patients without ATR/FNHTR were included in this study, respectively. The median BAT values associated with ATR- (n = 41) and FNHTR-causing (n = 5) blood products were 22.1% (range = 6.1%-77.0%) and 27.8% (range = 15.2%-47.8%), respectively, which were higher than the median value of 8.5% (range = 1.1%-40.9%) observed in blood products without a transfusion reaction. Dasatinib suppressed basophil activity. BAT values were comparable in patients with ATR regardless of severity. Meanwhile, BAT values analysed with blood products non-causal for ATR/FNHTR were higher in patients with ATR/FNHTR than in those without.

CONCLUSION

The IgE-mediated type I hypersensitivity may be involved in the pathogenesis of ATR and FNHTR. BAT analyses may help elucidate the underlying mechanisms and identify patients at risk.

Prevalence, Clinical Manifestations, Treatment, and Clinical Course of Chronic Urticaria in Elderly: A Systematic Review

Purpose

Data specific to the epidemiology, clinical features, and management of chronic urticaria (CU) in the geriatric population remain limited and not well understood. We aim to systematically review the prevalence, clinical manifestations, treatment, and clinical course of elderly patients with CU.

Patients and methods

Original articles that included data of elderly (aged >60 years) with CU that were published until February 2021 were searched in PubMed, Scopus, and Embase using predfefined search terms. Related articles were evaluated according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations.

Results

Among the included 85 studies and 1,112,066 elderly CU patients, most (57.4%) were women. The prevalence of elderly CU in the general population ranged from 0.2–2.8%, and from 0.7–33.3% among all CU patients. Compared to adult CU, elderly CU patients had a higher percentage of wheal alone (73.9%), and lower rate of positive autologous serum skin test and atopy. Gastrointestinal diseases were the most common comorbidity (71.9%), and there was a high rate of malignancies and autoimmune diseases. Second generation H₁-antihistamines were commonly used, and achievement of complete control was most often reported. Omalizumab was prescribed in 59 refractory patients, and a significant response to treatment was reported in most patients. The treatment of comorbidities also yielded significant improvement in CU.

Conclusion

Elderly CU was found to be different from adult CU in both clinical and laboratory aspects. H₁- antihistamines are effective as first-line therapy with minimal side-effects at licensed doses. Treatment of secondary causes is important since the elderly usually have age-related comorbidities.

Autoimmune chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is a debilitating mast cell-driven disease characterized by recurrent wheals and/or angioedema. Substantial progress has been made in dissecting the 2 main autoimmune mechanisms that drive the pathogenesis of CSU. Type I autoimmune (autoallergic) CSU is associated with IgE antibodies against autoantigens, for example, thyroid peroxidase and IL-24. Type IIb autoimmune CSU is mediated by autoantibodies that activate mast cells, for example, via IgE and FcεRI, and is present in less than 10% of patients with CSU when strict criteria are used, that is, triple positivity of autologous serum skin test, immunoassays for IgG autoantibodies, and basophil activation tests. A subpopulation of patients with CSU has both types. Type IIb autoimmune CSU is characterized by higher disease severity, concomitant autoimmune diseases, low levels of total IgE, elevated levels of IgG-anti-thyroid peroxidase, basopenia, eosinopenia, poor response to antihistamines and to omalizumab, and a good response to cyclosporine. Novel targeted therapies for CSU are under development such as ligelizumab, an anti-IgE, fenebrutinib and remibrutinib, Bruton's tyrosine kinase inhibitors, and dupilumab, an anti-IL-4Rα. Further studies should investigate the overlap between autoallergic and type IIb autoimmune CSU, optimize the diagnosis of both autoimmune endotypes using easy-to-perform, noninvasive, and inexpensive markers, and assess differences in response to therapy.

A European survey of management approaches in chronic urticaria in children: EAACI pediatric urticaria taskforce

BACKGROUND

Although well described in adults, there are scarce and heterogeneous data on the diagnosis and management of chronic urticaria (CU) in children (0-18 years) throughout Europe. Our aim was to explore country differences and identify the extent to which the EAACI/GA²LEN/EDF/WAO guideline recommendations for pediatric urticaria are implemented.

METHODS

The EAACI Task Force for pediatric CU disseminated an online clinical survey among EAACI pediatric section members. Members were asked to answer 35 multiple choice questions on current practices in their respective centers.

RESULTS

The survey was sent to 2,773 physicians of whom 358 (13.8%) responded, mainly pediatric allergists (80%) and pediatricians (49.7%), working in 69 countries. For diagnosis, Southern European countries used significantly more routine tests (eg, autoimmune testing, allergological tests, and parasitic investigation) than Northern European countries. Most respondents (60.3%) used a 2^nd -generation antihistamine as first-line treatment of whom 64.8% updosed as a second line. Omalizumab was used as a second-line treatment by 1.7% and third line by 20.7% of respondents. Most clinicians (65%) follow EAACI/WAO/GA2LEN/EDF guidelines when diagnosing CU, and only 7.3% follow no specific guidelines. Some clinicians prefer to follow national guidelines (18.4%, mainly Northern European) or the AAAAI practice parameter (1.7%).

CONCLUSIONS

Even though most members of the Pediatric Section of EAACI are familiar with the EAACI/WAO/GA2LEN/EDF guidelines, a significant number do not follow them. Also, the large variation in diagnosis and treatment strengthens the need to re-evaluate, update, and standardize guidelines on the diagnosis and management of CU in children.

What Basophil Testing Tells Us About CSU Patients - Results of the CORSA Study

Basophil testing is the most effective single approach for diagnosing type-IIb autoimmune chronic spontaneous urticaria (TIIbaiCSU). A positive basophil test has been linked to long disease duration, higher disease activity, a poor response to antihistamines and omalizumab, and a better response to cyclosporine and fenebrutinib. As of now it is unclear what other features are connected to a positive basophil test in chronic spontaneous urticaria (CSU). We aimed to identify features of basophil test-positive CSU patients. We performed a cross-sectional study of 85 CSU patients. Basophil testing was done with the basophil activation test (BAT) and the basophil histamine release assay (BHRA). Data were analysed using SPSS: Student's t-test, Chi-square test, Odds Ratio, Spearman's correlation test. Of 85 CSU patients, 44% and 28% tested positive with the BAT and BHRA, respectively. These patients showed higher disease activity and impact, lower levels of disease control and total serum IgE, as well as higher rates of having a positive autologous serum skin test (ASST), angioedema, nocturnal symptoms, symptoms for >5 days/week, and thyroid autoantibodies. The ASST, by itself, was not a good predictor of basophil test results, but it predicted a positive basophil test in up to 100% of cases when combined with angioedema, thyroid autoantibodies or low IgE. In conclusion, a positive basophil test is linked to known features of TIIbaiCSU and novel characteristics including nocturnal symptoms. Further studies on basophil test-positive and -negative CSU patients can help to better understand CSU endotypes and to develop better management approaches.

Autoimmune Chronic Spontaneous Urticaria Detection with IgG Anti-TPO and Total IgE

BACKGROUND

Autoimmune chronic spontaneous urticaria (aiCSU) comes with high disease activity and poor response to treatment. Recently, elevated levels of IgG anti-thyroid peroxidase (aTPO) and low levels of total IgE were reported to be common in aiCSU.

OBJECTIVE

To investigate how high aTPO and low IgE individually and combined are linked to features of aiCSU, including treatment responses.

METHODS

We analyzed records of patients with CSU from 2 independent cohorts (n = 1120) for demographic, clinical, and laboratory parameters and treatment responses. Total IgE and aTPO were measured, and 4 markers of aiCSU were analyzed: autologous serum skin test, basophil activation test (BAT), and blood eosinophil and basophil counts. Cutoff values were greater than or equal to 34 kU/L (high aTPO) and less than 40 IU/mL (low total IgE).

RESULTS

One of 10 patients with CSU had both high aTPO and low IgE (aTPO↑IgE↓, 11%, n = 123). aTPO↑IgE↓ was linked to higher age at CSU onset, being female, angioedema, and shorter CSU duration. aTPO↑IgE↓ was associated with markers of aiCSU, that is, BAT and autologous serum skin test positivity, basopenia, and eosinopenia (P < .01 for all). Almost half the patients with aTPO↑IgE↓ (44%, 19 of 43) had a positive BAT result, the best single marker for aiCSU, versus 12% (43 of 344) of patients without aTPO↑IgE↓ (P < .001). Relative risk of showing BAT positivity for a patient with aTPO↑IgE↓ is 3.636 (95% CI, 2.382-5.551). Patients with aTPO↑IgE↓ showed low response rates to antihistamine treatment as compared with patients without aTPO↑IgE↓ (30% vs 47%; P = .01).

CONCLUSIONS

Our findings suggest that aTPO↑IgE↓ is a useful diagnostic marker for aiCSU in everyday clinical practice.

Biomarkers of chronic spontaneous urticaria and their clinical implications

Introduction: Chronic spontaneous urticaria (CSU) is a frequent disorder in which activation of effector cells and histamine release can be induced via several distinct pathogenetic mechanisms. Much work has been carried out to identify biomarkers useful for classifying CSU patients, and to predict their response to currently available treatments.Areas covered: The recent literature dealing with CSU biomarkers was screened in PubMed and Google Scholar using 'chronic spontaneous urticaria', 'biomarker', 'diagnosis', 'therapy' and 'treatment response' as key words. The characteristics found in relevant papers were divided into clinical and serological biomarkers of (a) clinical severity/disease activity, and (b) response to treatments.Expert opinion: A diagnostic biomarker for CSU is still missing. Most biomarkers described so far do not seem to possess sufficient specificity for this disease. Basopenia and the activation of the coagulation cascade might be biomarkers of disease activity and severity, but information available so far is insufficient to consider their routine use. Markers suggesting IgG-mediated autoimmunity (autologous serum skin test, basophil activation/histamine release assays, low total IgE) seem to identify patients less prone to respond to omalizumab but responsive to cyclosporine. In contrast, 'autoallergy' (i.e. the presence of IgE to autoallergens), which is often associated with elevated IgE levels seems to identify patients who will respond to omalizumab.

Comparative analysis of clinical and laboratory parameters of autoimmune and idiopathic chronic urticaria patients

Background: According to the cause, chronic urticaria is most frequently divided into autoimmune and idiopathic urticaria. Aim of the paper was to determine the frequency of autoimmune urticaria using autologous serum skin testing and a comparative analysis of chronic idiopathic and chronic autoimmune urticaria by disease course, severity and most common comorbidities. Methods: Analysis covered 64 adult patients of both sexes with chronic urticaria, divided into two groups according to their positivity in autologous serum skin testing (group I with positive test and group II with negative test). General haematological and biochemical parameters, antithyroid antibodies, hepatitis serum markers, Helicobacter pylori and Borrelia burgdorferi antibodies were performed for patients in both groups. First group patients were treated by autologous blood therapy (autohaemotherapy). The analytical statistical tool SPSS (Statistical Product and Service Solutions) version 20 for descriptive statistics and statistical methods was used. The significance level used was p = 0.05. Results: The frequency of positive autologous serum test in total population of patients with chronic urticaria was 43.8 %. The average duration of urticaria was 20 months in both groups. Statistically significant difference was found in weekly scores between the studied groups (p = 0.032) in favour of chronic autoimmune urticaria with a positive autologous serum test. Subjects with chronic autoimmune urticaria had a significantly higher association with autoimmune thyroid diseases. Conclusions: Direct relation was established between the use of autologous blood therapy in patients with autoimmune chronic urticaria and improvement of the clinical picture.

Chronic Spontaneous Urticaria: A Review of Pathological Mechanisms, Diagnosis, Clinical Management, and Treatment

Urticaria is a poorly understood and underestimated clinical condition characterised by the sudden onset of itchy wheals and/or angioedema, which usually resolve within 24 and 72 hours, respectively. It is generally classified as being acute (lasting <6 weeks) or chronic (continuous or intermittent for ≥6 weeks). Chronic urticaria can be further classified as chronic spontaneous urticaria (CSU) and chronic inducible urticaria, appearing in response to specific eliciting factors, such as heat, cold, or sun exposure, or following the application of pressure. Scientific advances have been made in the understanding of pathological mechanisms and treatment, especially associated with CSU. The exact pathological mechanism of how urticaria develops is still not yet fully understood, but the clinical implications on the patients’ quality of life are severe and have been associated with mental disorders and metabolic diseases. The diagnosis of urticaria is based on medical history and clinical manifestations. The treatment pathway begins with the administration of second-generation, nonsedating, nonimpairing histamine 1 receptor antihistamines and, in case of nonresponse, with new-generation biological drugs. The current review presents an update of the pathological mechanisms, diagnosis, clinical management, and treatment of CSU. It also focusses on the future implications of new-generation drugs and their effects on the clinical practice.

H. Grattan C, Jakob T, Konstantinou GN, Raap U, Skov PS, Staubach P, Kromminga A, Zhang K, Bindslev‐Jensen C, Daschner A, Kinaciyan T, Knol EF, Makris M, Marrouche N, Schmid‐Grendelmeier P, Sussman G, Toubi E, Church MK, Maurer M. Biomarkers and clinical characteristics of autoimmune chronic spontaneous urticaria: Results of the PURIST Study

BACKGROUND

Autoimmune chronic spontaneous urticaria (aiCSU) is an important subtype of chronic spontaneous urticaria (CSU) in which functional IgG autoantibodies to IgE or its high-affinity receptor (FcεRI) induces mast cell degranulation and subsequent symptom development. However, it has not been tightly characterized. This study aimed to better define the clinical and immunological features and to explore potential biomarkers of aiCSU.

METHODS

This was a multinational, multicenter study of 182 CSU patients. The clinical features studied included: urticaria activity and impact (UAS7 and quality of life); autologous serum skin test (ASST); IgG anti-FcεRI and IgG anti-IgE; IgG-anti-thyroperoxidase (IgG anti-TPO); total serum IgE; and basophil reactivity (BASO) using the basophil activation test (BAT) and basophil histamine release assay (BHRA).

RESULTS

Of the 182 patients, 107 (59%) were ASST+, 46 (25%) were BASO+, and 105 (58%) were IgG anti-FcεRI+/IgE+. Fifteen patients (8%) fulfilled all three criteria of aiCSU. aiCSU patients appeared more severe (UAS7 21 vs 9 P < 0.016) but showed no other clinical or demographic differences from non-aiCSU patients. aiCSU patients also had markedly lower total IgE levels (P < 0.0001) and higher IgG anti-TPO levels (P < 0.001). Of biomarkers, positive BAT and BHRA tests were 69% and 88% predictive of aiCSU, respectively.

CONCLUSIONS

aiCSU is a relatively small but immunologically distinct subtype of CSU that cannot be identified by routine clinical parameters. Inclusion of BHRA or BAT in the diagnostic workup of CSU patients may aid identification of aiCSU patients, who may have a different prognosis and benefit from specific management.

Emerging Biomarkers and Therapeutic Pipelines for Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is defined as the appearance of evanescent wheals, angioedema, or both, for at least 6 weeks. CSU is associated with intense pruritus and poor quality of life, with higher odds of reporting depression, anxiety, and sleep difficulty. As of yet, the assessment of the activity and course of the disease along with the response to several treatments in CSU are based purely on the patient's medical history and the use of the patient-reported outcomes. Recently, several reports have suggested that certain parameters could be considered as potential disease-related biomarkers. Moreover, with the advent of such biomarkers, newer biologic agents are coming forth to revolutionize the management of potential refractory diseases such as CSU. The purpose of this article is to review the most promising biomarkers related to important aspects of CSU, such as the disease activity, the therapeutic response, and the natural history of the disease, and discuss the mechanisms of action and therapeutic effectiveness of the latest agents available or currently under investigation for the management of antihistamine-refractory CSU. The knowledge of these features could have an important impact on the management and follow-up of patients with CSU.

Response to: Bias in the use of a SSClow/CCR3pos gate to capture basophils in chronic urticaria?

A response to Chirumbolo S, Bjørklund G, and Vella A, Bias in the use of a SSClow/CCR3pos gate to capture basophils in chronic urticaria? Immunobiology, 224(3), 2019, 353-354.

Basophil Activation Test: Old and New Applications in Allergy

PURPOSE OF REVIEW

The basophil activation test (BAT) using flow cytometry has supplanted traditional methods of measuring basophil degranulation using histamine and other mediator release, and can be used for clinical applications as well as to explore the immune mechanisms of effector cell response to allergen. This review discusses the advancements made in clinical, diagnostic and laboratory research of allergy utilizing an ever-evolving BAT.

RECENT FINDINGS

Being an in vitro surrogate of the allergic reaction that happens in vivo in the sick patient, the BAT can be used to support the diagnosis of various allergic conditions, such as food, drug, respiratory and insect venom allergies, and the assessment of clinical response to allergen-specific immunotherapy and other immunomodulatory treatments. The BAT can also be used for research purposes to explore the mechanisms of allergy and tolerance at the level of the basophil, for instance by manipulating IgE and IgG and their receptors and by studying intracellular signalling cascade in response to allergen. This review covers the applications of the BAT to the clinical management of allergic patients and the increased understanding of the mechanisms of immune response to allergens as well as technological advancements made in recent years.

Thyroid Autoimmunity and Autoimmunity in Chronic Spontaneous Urticaria Linked to Disease Severity, Therapeutic Response, and Time to Remission in Patients with Chronic Spontaneous Urticaria

Background

Chronic spontaneous urticaria (CSU) is autoimmune in nature and associated with thyroid autoimmunity (TA), but evidence on autoimmunity in relation to CSU progression and prognosis is limited. We evaluated whether TA and autoimmunity in CSU are correlated with disease severity, therapeutic response, and time to remission and establish an association between CSU characteristics linked to thyroid autoantibody.

Methods

Medical records of patients diagnosed with urticaria attending outpatient dermatology clinic at a university-based hospital from 2013 to 2017 were retrospectively reviewed. Data on the clinical characteristics, laboratory investigations particularly thyroid antibody titers, autologous serum skin test (ASST) and autologous plasma skin test (APST) results and their link to disease severity, treatments, and time to remission of CSU patients were analyzed.

Results

Of 1,096 patients with urticaria, 60.2% had CSU. Three-hundred patients fulfilled the inclusion criteria for CSU with complete thyroid antibody testing. Positive TA was significantly associated with female gender and age > 35 years (p = 0.008). Antithyroid peroxidase (anti-TPO)-positive patients suffered from CSU longer than 12 and 18 months compared to anti-TPO-negative patients (100.0% vs. 82.6%, p = 0.042, and 100.0% vs. 75.9% p = 0.020, respectively). The presence of urticarial attacks > 4 days/week was significantly seen in ASST and APST-positive patients compared to those without (84.6% vs. 61.3%, p = 0.011, and 85.3% vs. 61.8%, p = 0.006, respectively). Positive APST patients were more difficult to treat than those with negative results (61.2% vs. 37.8%, p = 0.017).

Conclusions

Antithyroid peroxidase is a predictor of time to remission, while autologous skin testing is linked to disease severity (ASST and APST) and therapeutic response (APST) in CSU patients.

The EAACI/GA²LEN/EDF/WAO guideline for the definition, classification, diagnosis and management of urticaria

This evidence- and consensus-based guideline was developed following the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. The conference was held on 1 December 2016. It is a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the EU-founded network of excellence, the Global Allergy and Asthma European Network (GA²LEN), the European Dermatology Forum (EDF) and the World Allergy Organization (WAO) with the participation of 48 delegates of 42 national and international societies. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell-driven disease, presenting with wheals, angioedema, or both. The lifetime prevalence for acute urticaria is approximately 20%. Chronic spontaneous urticaria and other chronic forms of urticaria are disabling, impair quality of life and affect performance at work and school. This guideline covers the definition and classification of urticaria, taking into account the recent progress in identifying its causes, eliciting factors and pathomechanisms. In addition, it outlines evidence-based diagnostic and therapeutic approaches for the different subtypes of urticaria.

Comorbidity of chronic spontaneous urticaria and autoimmune thyroid diseases: A systematic review

Patients with chronic spontaneous urticaria (CSU) are widely held to often have other autoimmune disorders, including autoimmune thyroid disease. Here, we systematically evaluated the literature on the prevalence of thyroid autoimmunity in CSU and vice versa. There is a strong link between CSU and elevated levels of IgG antithyroid autoantibodies (AAbs), with most of a large number of studies reporting rates of ≥10%. Levels of IgG against thyroid peroxidase (TPO) are more often elevated in CSU than those of other IgG antithyroid AAbs (strong evidence). Levels of IgG antithyroid AAbs are more often elevated in adult patients with CSU than in children (strong evidence). Patients with CSU exhibit significantly higher levels of IgG antithyroid AAbs (strong evidence) and IgE-anti-TPO (weak evidence) than controls. Elevated IgG antithyroid AAbs in CSU are linked to the use of glucocorticoids (weak evidence) but not to disease duration or severity/activity, gender, age, or ASST response (inconsistent evidence). Thyroid dysfunction rates are increased in patients with CSU (strong evidence). Hypothyroidism and Hashimoto's thyroiditis are more common than hyperthyroidism and Graves' disease (strong evidence). Thyroid dysfunction is more common in adult patients with CSU than in children (strong evidence) and in female than in male patients with CSU (weak evidence). Urticaria including CSU is more prevalent in patients with thyroid autoimmunity than in controls (weak evidence). CSU can improve in response to treatment with levothyroxine or other thyroid drugs (strong evidence). Pathogenic mechanisms in CSU patients with thyroid autoimmunity may include IgE against autoantigens, immune complexes, and complement.