Serum-induced basophil CD63 expression by means of a tricolour flow cytometric method for the in vitro diagnosis of chronic urticaria

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.

Increased CD123 + HLA-DR- Granulocytes in Allergic Rhinitis and Influence of Allergens on Expression of Cell Membrane Markers

BACKGROUND

It is reported that CD123 + HLA-DR- cells in PBMC are basophils, and CD203c, CD63, and FcεRI molecules are activation markers of basophils. However, little is known of CD123 + HLA-DR-cells in blood granulocytes.

OBJECTIVE

To investigate the presence of CD123 + HLA-DR- cells in the blood granulocytes and peripheral PBMC of patients with allergic rhinitis (AR), as well as the impact of allergens on the cell membrane markers of basophils.

METHODS

Flow cytometry was used to detect the expression of the membrane molecules.

RESULTS

While CD123 + HLA-DR- PBMCs are representative of basophils, their presence did not significantly change in patients with AR. In contrast, both the percentage and number of CD123 + HLA-DR- granulocytes, which make up only up to 50% of basophils, were significantly increased in patients with seasonal (sAR) and perennial AR (pAR). CD63+, CD203c+, and FcεRIα+ cells within CD123 + HLA-DR- granulocytes also showed enhanced activity in patients with AR. Allergen extracts from house dust mite allergen extract (HDME) and Artemisia sieversiana wild extract further increased the number of CD123 + HLA-DR- cells in granulocytes of sAR and pAR patients, as well as in PBMCs of pAR patients.

CONCLUSIONS

The use of CD123 + HLA-DR- granulocytes and PBMC may not be sufficient for diagnosing AR. Allergens could potentially contribute to the development of AR by influencing the number of CD123 + HLA-DR- cells, as well as the expression of CD63, CD203c, and FcεRIαin these cells.

Autoimmune Mast Cell Activation Test as a Diagnostic Tool in Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is associated with skin mast cell activation, and its triggering mechanisms are not completely elucidated. Evidence suggests an autoimmune component of CSU. Our aim was to assess the usefulness of an autoimmune mast cell activation test (aiMAT) for diagnosing and differentiating CSU into different subtypes. We enrolled 43 patients with active, uncontrolled CSU before starting treatment with omalizumab and 15 controls. Patients were evaluated based on omalizumab response. aiMATs were performed using non-IgE-sensitized (NS) or myeloma IgE-sensitized (S) LAD2 cells, which were then stimulated with CSU/control sera (25 µL and 10 µL). The expression of CD63 was assessed with flow cytometry. CD63 response on NS-LAD2 was significantly increased in CSU patients compared to controls after the stimulation with 25 µL CSU/control sera (p = 0.0007) and with 10 µL CSU/control sera (p = 0.0001). The ROC curve analysis demonstrated an area under the curve (AUC) of 0.82. The cutoff for autoimmune-non-IgE-sensitized-MAT was 40.3% CD63+ LAD2, which resulted in 73.3% sensitivity and 81.4% specificity. CD63 response on S-LAD2 was significantly increased in CSU patients compared to controls after the stimulation with 25 µL CSU/control sera (p = 0.03). The ROC curve analysis demonstrated an AUC of 0.66. The cutoff for the autoimmune-myeloma IgE-sensitized-MAT was 58.4% CD63+ cells, which resulted in 62.8% sensitivity and 66.7% specificity. Overall, 36 out of 43 (84%) patients responded to omalizumab, and 7 (16%) were nonresponders. We found no differences between LAD2 CD63 response and response to omalizumab. In conclusion, aiMAT could represent a new diagnostic tool in CSU. Additional studies are needed to evaluate the potential benefits during omalizumab therapy.

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.

Basophil activation in insect venom allergy: comparison of an established test using liquid reagents with a test using 5-color tubes with dried antibody reagents

BACKGROUND

Flow cytometry-based basophil activation tests (BAT) have been performed with various modifications, differing in the use of distinct identification and activation markers. Established tests use liquid reagents while a new development involves the use of tubes with dried antibody reagents. The aim of this pilot study was to compare these two techniques in patients with insect venom allergy.

METHODS

Seventeen patients with an insect venom allergy were included in the study. The established "BAT 1" utilizes conventional antibody solutions of anti-CCR3 for basophil identification and anti-CD63 to assess basophil activation, whereas "BAT 2" uses dried anti-CD45, anti-CD3, anti-CRTH2, anti-203c and anti-CD63 for identification and activation measurement of basophils. Negative and positive controls as well as incubations with honey bee venom and yellow jacket venom at three concentrations were performed.

RESULTS

Seven patients had to be excluded due to low basophil counts, high values in negative controls or negative positive controls. For the remaining 10 patients the overall mean (± SD) difference in activated basophils between the two tests was 0.2 (± 12.2) %P. In a Bland-Altman plot, the limit of agreement (LoA) ranged from 24.0 to -23.7. In the qualitative evaluation (value below/above cut-off) Cohen's kappa was 0.77 indicating substantial agreement. BAT 2 took longer to perform than BAT 1 and was more expensive.

CONCLUSION

The BAT 2 technique represents an interesting innovation, however, it was found to be less suitable compared to an established BAT for the routine diagnosis of insect venom allergies.

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.

Successful Treatment of Autoimmune Urticaria with Low-Dose Prednisolone Therapy Administered for a Few Months: A Case Series of 42 Patients

BACKGROUND

Chronic spontaneous urticaria (CSU) is defined as symptoms of urticaria persisting for 6 weeks or more without obvious cause. Autologous serum skin test (ASST) positivity in patients with CSU is considered to be associated with autoimmune urticaria (AIU).

METHODS

In this retrospective study we retrieved the medical records of 1,073 urticaria patients seen at the Department of Dermatology and Allergology of Szeged University between January 2005 and February 2014. Forty-two patients (36 female and 6 male) met the study criteria by having CSU and giving positive results in the ASST. Our aim was to assess the clinical efficacy and safety of low-dose oral prednisolone therapy administered to patients with antihistamine-refractory ASST-positive CSU for a few months. Patients were given an initial dose (40 mg/day) of prednisolone until the complete resolution of the symptoms, usually 7-10 days, and then the dose was gradually decreased, as in other autoimmune diseases.

RESULTS

Prednisolone therapy lasted for an average of 3.6 months and a complete long-lasting response was achieved in 35 of 42 AIU patients (83.3%). The follow-up period was at least 36 months (3 years) for each AIU patient; the longest follow-up time was 139 months (11.5 years). None of the patients reported any considerable side effects.

CONCLUSION

Based on our results, we suggest that the use of this treatment could be an alternative for the treatment of AIU. Our present results also highlight the need for other therapies in a small percentage of AIU patients. Our results suggest that AIU represents a transient autoimmunity that can be successfully treated with low-dose steroid therapy administered for a few months.

Cyclosporine for Chronic Spontaneous Urticaria: A Meta-Analysis and Systematic Review

BACKGROUND

Despite widely recommended usage of cyclosporine A (CsA) in chronic spontaneous urticaria (CSU), there is no meta-analysis concerning its efficacy and safety.

OBJECTIVE

To meta-analyze and review the efficacy and safety of CsA in CSU.

METHODS

Efficacy was assessed by the relative change in urticaria activity score at 4 weeks and response rates at 4, 8, and 12 weeks. Safety was assessed by analyzing the number of patients with 1 or more adverse event.

RESULTS

Eighteen studies (909 participants) including 2 randomized controlled trials were included, with 125, 363, and 266 patients with CSU receiving very low (<2 mg/kg/d), low (from 2 to< 4 mg/kg/d), and moderate (4-5 mg/kg/d) doses of CsA, respectively. After 4 weeks, the mean relative change in urticaria activity score of CsA-treated patients was -17.89, whereas that of controls was -2.3. The overall response rate to CsA treatment with low to moderate doses at 4, 8, and 12 weeks was 54%, 66%, and 73%, respectively. No studies of very low-dose CsA evaluated response rates at 4, 8, and 12 weeks. Among patients treated with very low, low, and moderate doses of CsA, 6%, 23%, and 57% experienced 1 or more adverse event, respectively.

CONCLUSIONS

Given the limited number and quality of studies, our results should be interpreted with caution. CsA is effective at low to moderate doses. Adverse events appear to be dose dependent and occur in more than half the patients treated with moderate doses of CsA. We suggest that the appropriate dosage of CsA for CSU may range from 1 to 5 mg/kg/d, and 3 mg/kg/d is a reasonable starting dose for most patients.

Basophil markers for identification and activation in the indirect basophil activation test by flow cytometry for diagnosis of autoimmune urticaria

Background

The indirect basophil activation test using flow cytometry is a promising tool for autoimmune urticaria diagnosis. We aimed to identify better donor basophils (from atopic vs. non-atopic donors and interleukin-3 primed vs. unprimed basophils) and improve basophil identification and activation markers (eotaxin CC chemokine receptor-3 [CCR3] vs. CD123 and CD63 vs. CD203c).

Methods

Donor basophils were obtained from non-atopic and atopic group O donors. Positive control sera were artificially prepared to simulate autoimmune urticaria patients' sera. Patient sera were obtained from nine children with chronic urticaria. Assay sensitivity was compared among each variation by using positive control sera (n=21), applying cutoff values defined from negative control sera (n=20).

Results

For basophil identification, a combination of CCR3 and CD123 markers revealed a higher correlation with automated complete blood count (r=0.530) compared with that observed using CD123 (r=0.498) or CCR3 alone (r=0.195). Three activation markers on the atopic donor basophils attained 100% assay sensitivity: CD203c on unprimed basophils, CD63+CD203+ or CD63 alone on primed basophils; however, these markers on the non-atopic donor basophils attained lower assay sensitivity.

Conclusions

For basophil identification markers, a combination of CD123 and CCR3 is recommended, while CD123 alone may be used as an alternative. Donor basophils should be obtained from an atopic donor. For basophil activation markers, either CD203c alone on unprimed basophils or CD203c and CD63 on primed basophils are recommended, while CD63 alone on primed basophils may be used as an alternative.

Positive CD63 Basophil Activation Tests Are Common in Children with Chronic Spontaneous Urticaria and Linked to High Disease Activity

BACKGROUND

The basophil activation test (BAT) using CD63 expression is a sensitive and specific tool for the diagnostic workup of autoimmune chronic spontaneous urticaria (CSU). The definition of a positive BAT is directly dependent on the reference range and the cutoff values established in control populations. As of now, the pediatric reference range and cutoff values of the CD63 BAT remain to be established.

METHODS

In this study, we analyzed CD63 expression in 80 children (1-17 years old) without chronic urticaria (i.e., controls) and compared the values to those of a pediatric cohort of 105 CSU patients and 23 physical urticaria (PU) patients.

RESULTS

Based on the log-normal distribution of CD63 values in control subjects, the reference range and the cutoff for positive CD63 BAT values was established to be 1.2-1.8% (95% CI) and 1.8%, respectively. Children with CSU showed significantly elevated and significantly increased BAT values compared to healthy controls (Wilcoxon rank test p value <0.001). In contrast, no difference was found between BAT results in controls and PU patients. In pediatric CSU patients, a higher disease activity was associated with higher BAT values.

CONCLUSIONS

Our study provides, for the first time, reference and cutoff values for the CD63 BAT in children. Our findings show that positive CD63 BAT are common in children with CSU and linked to a high disease activity.

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

Introduction

The basophil activation test showing CD63 up regulation could be a specific and sensitive in vitro complementary text to the in vivo autologous serum skin test for the activity assessment of the patients suffering autoimmune chronic spontaneous urticaria. The aim of this study is to define the basophil activation test as a useful tool in clinical practice in order to identify those patients with more active disease.

Methods

We screened 139 patients (96 women) diagnosed of chronic spontaneous urticaria using simultaneously autologous serum skin test and basophil activation test and their relationship with disease activity.

Results

Positive autologous serum skin test was found in 56.8%; from them, 31.6% were basophil activation test positive. Negative autologous serum skin test result was found in the 43.2% of the sample that showed negative CD63 expression results in all cases, except one. Patients with positive autologous serum skin test and positive CD63 by basophil activation test showed significant higher Urticaria Activity Score of 7 days (P = 0.004) and of 3 weeks (P = 0.001) than patients with positive autologous serum skin test and negative CD63 (mean ± standard deviation [SD] 26.57 ± 10.56 versus 18.40 ± 12.05 for the Urticaria Activity Score of 7 days and 56.47 ± 23.78 versus 39.88 ± 25.44 for the Urticaria Activity Score of 3 weeks).

Conclusions

The CD63 expression on basophils appears as a reliable in vitro marker, useful in clinical practice in combination with autologous serum skin test to define chronic spontaneous urticaria patients with the highest urticaria activity that impairs a normal life.

Optimizing of the basophil activation test: Comparison of different basophil identification markers

BACKGROUND

Flowcytometric identification of basophils is a prerequisite for measuring activation of basophils with IgE-dependent or IgE-independent stimuli. Aim of this study was to compare different marker combinations in a simultaneous multicolor flowcytometric measurement.

METHODS

Ten patients with a grass pollen allergy and three controls were included in the study. Basophilic cells were gated by using anti-CCR3, anti-IgE, anti-CRTH2, anti-CD203c, and anti-CD3. Cells were activated by a monoclonal anti-FcεRI antibody, N-formyl-methionyl-leucyl-phenylalanine (fMLP), and the allergen extract Phleum pratense. The activation marker anti-CD63 was used.

RESULTS

The highest relative number of basophils was found with anti-CCR3+ cells, anti-IgE+ and anti-IgE+ /anti-CD203c+ cells, the lowest with CRTH2+/CD203c+/CD3- cells. A very good and good concordance of CCR3+ cells was seen with CCR3+/CD3- cells and CRTH2+/CD203c+/CD3- cells in all experiments. The contamination of the CCR3+ population with CD3+ cells and the contamination of the IgE+-population with CCR3- cells and CD203- cells were the lowest compared to all other marker combinations.

CONCLUSIONS

As the highest relative number of basophils was identified by anti-CCR3 followed by the anti-IgE and anti-IgE/antiCD203c positive population in most cases, these markers can generally be recommended for identification of basophils. If a basophil population with very high purity is needed, anti-IgE should be chosen.

A rapid method of detecting autoantibody against FcεRIα for chronic spontaneous urticaria

Background

Chronic spontaneous urticaria (CU) is a common skin disorder, with an estimated prevalence of 0.5–1.8% in most populations. Around 30–50% of CU patients have an autoimmune etiology, with autoantibodies (autoAbs) against IgE, FcεRIα, and FcεRII/CD23. Although the in vivo autologous serum skin test (ASST) and in vitro histamine release/activation assay are the most frequently used screening methods, these two have many limitations and do not directly measure susceptible autoAbs. This study aimed to establish an in vitro rapid screening test using recombinant autoantigen FcεRIα(rFcεRIα) to improve the diagnosis of autoimmune urticaria.

Methods

Forty patients with CU and 20 healthy individuals were enrolled. After PCR-based cloning and the production of extracellular fragments of the FcεRIαprotein using the E. coli expression system, serum autoAb to rFcεRIαwas evaluated using in-house ELISA and rapid immunodot test.

Results

In ELISA-based detection, 14 out of 20 CU-ASST(+) patients exhibited anti- FcεRIαresponses, whereas five of the 20 CU-ASST(-) and two of the 20 non-CU patients showed autoantibody background in the assay. For the immunodot test, 55% (11/20) of the CU-ASST(+) sera exhibited anti-FcεRIαreactivity. There was no false positive among the CU-ASST(-) and non-CU groups. Using clinical urticaria plus ASST(+) as the gold standard, in-house ELISA had 70% sensitivity, 82.5% specificity, and positive likelihood ratio of 4, while immunodot had 55% sensitivity, 100% specificity, and positive likelihood ratio >55.

Conclusions

This study has developed a rapid immunodot method with high specificity for detecting autoAb to FcεRIαin patients with CU. Preliminary data indicates that this immunodot technique has the potential to be a routine diagnostic assay for autoimmune CU.

Basophil activation test with food additives in chronic urticaria patients

The role of food additives in chronic urticaria (CU) is still under investigation. In this study, we aimed to explore the association between food additives and CU by using the basophil activation test (BAT). The BAT using 15 common food additives was performed for 15 patients with CU who had a history of recurrent urticarial aggravation following intake of various foods without a definite food-specific IgE. Of the 15 patients studied, two (13.3%) showed positive BAT results for one of the tested food additives. One patient responded to monosodium glutamate, showing 18.7% of CD203c-positive basophils. Another patient showed a positive BAT result to sodium benzoate. Both patients had clinical correlations with the agents, which were partly determined by elimination diets. The present study suggested that at least a small proportion of patients with CU had symptoms associated with food additives. The results may suggest the potential utility of the BAT to identity the role of food additives in CU.

Differences in IgE mediated basophil degranulation induced by proteic fractions from whole flea body extract in patients with papular urticaria by flea bite and healthy controls

Background

Papular urticaria by flea bite (PUFB) is a chronic inflammatory disease in children. The aim of this study was to assess the functional activity of IgE to protein fractions from flea body extract, through basophil degranulation in PUFB patients and controls.

Methods

Basophil degranulation, measured by overexpression of CD63 surface molecules, was evaluated by flow cytometry in samples from patients and controls. Cell stimulation was performed with three fractions with different molecular weight from flea body extract using a Basotest® modified protocol. Mann–Whitney U-test was used for comparisons.

Results

Specific IgE from PUFB patients and healthy controls induced basophil degranulation to flea body extract with no significant differences between them (16.2 ± 3.1% vs 13.6 ± 2.8% p = 0.77). However, when flea extract was analyzed in fractions with proteins ranging different molecular weights, significant differences were observed on the response from patients compared with controls to <50 kD (14.9 ± 5.1% vs 9.7 ± 2.1% p = 0.0058) and 50–100 kD proteic fractions (8.3 ± 3.2% vs 2.8 ± 1.6% p = 0.0021).

Conclusion

In this study, was established that the differential response by IgE, in PUFB, depends from the molecular weight of the antigens contained in the flea extract. These antigens may be related to 30–35 kD proteins previously described as major allergens.

EAACI taskforce position paper: evidence for autoimmune urticaria and proposal for defining diagnostic criteria

An autoimmune subset of chronic spontaneous urticaria is increasingly being recognized internationally, based on laboratory and clinical evidence that has accrued over the last 20 years. This evidence has been reviewed by a taskforce of the Dermatology section of the European Academy of Allergy and Clinical Immunology. Functional autoantibodies in chronic urticaria (CU) patient sera have been demonstrated against IgE and FcεRIα by basophil and mast cell histamine release assays and by basophil activation assays. Antibody specificity has been confirmed by immunoassay, but there is a poor correlation between functionality and immunoreactivity. Approximately 25% of CU patients have a positive basophil histamine release assay and show autoreactivity (a positive autologous serum skin test), whereas 50% are negative regarding both. Functionality of CU sera appears to be complement dependent on mast cells but not exclusively on basophils. Basophil activation by CU sera is predominantly restricted to IgG1 and IgG3 subclasses. Circumstantial evidence for CU being an autoimmune disease comes from an observed association with other autoimmune diseases, a strong association between serum functionality and HLA-DR4 haplotype and the good response of CU patients to immunotherapies. It was proposed that a study should be undertaken to prospectively validate potentially relevant clinical criteria (from the history, examination and routinely available clinical investigations) against a new 'gold standard' for the diagnosis of ACU (positive autoreactivity, functional bioassay and immunoassay) to define preliminary criteria sets for the diagnosis of ACU based on clinical and laboratory features with highest individual sensitivity and specificity.

Basophil activation test compared to skin prick test and fluorescence enzyme immunoassay for aeroallergen-specific Immunoglobulin-E

Background

Skin prick test (SPT) and fluorescence enzyme immunoassay (FEIA) are widely used for the diagnosis of Immunoglobulin-E (IgE)-mediated allergic disease. Basophil activation test (BAT) could obviate disadvantages of SPT and FEIA. However, it is not known whether BAT gives similar results as SPT or FEIA for aeroallergens.

Objectives

In this study, we compared the results of SPT, BAT and FEIA for different aeroallergens.

Methods

We performed BAT, SPT and FEIA in 41 atopic subjects (symptomatic and with positive SPT for at least 1 of 9 common aeroallergens) and 31 non-atopic subjects (asymptomatic and with negative SPT).

Results

Correlations between SPT and BAT, SPT and FEIA, and BAT and FEIA results were statistically significant but imperfect. Using SPT as the "gold standard", BAT and FEIA were similar in sensitivity. However, BAT had lower specificity than FEIA. False positive (BAT^posSPT^neg) results were frequent in those atopic subjects who were allergic by SPT to a different allergen and rare in non-atopic subjects. The false positivity in atopic subjects was due in part to high levels of serum Total-IgE (T-IgE) levels in atopic individuals that lead to basophil activation upon staining with fluorochrome-labeled anti-IgE.

Conclusion

As an alternative to SPT in persons allergic to aeroallergens, BAT in its present form is useful for distinguishing atopic from non-atopic persons. However, BAT in its present form is less specific than FEIA when determining the allergen which a patient is allergic to. This is due to IgE staining-induced activation of atopic person's basophils and/or nonspecific hyperreactivity of atopic person's basophils.

Usefulness of the CD63 basophil activation test in detecting Anisakis hypersensitivity in patients with chronic urticaria: diagnosis and follow-up

BACKGROUND

The basophil activation test (BAT) has been recently described as a useful in vitro tool for diagnosis of allergy to Anisakis species in patients with acute urticaria.

AIM

To evaluate the relationship between sensitization to Anisakis simplex and chronic urticaria (CU), using flow cytometry analysis of in vitro BAT. Methods.  A. simplex sensitization was evaluated in patients with CU (n = 57) and in atopic (n = 22) and healthy controls (n = 20) by means of skin prick test (SPT), specific IgE and Anisakis-induced BAT using a triple-labelled strategy with anti-CD123, anti-human leucocyte antigen DR and anti-CD63 antibodies. During a follow-up period of 6 months in 10 patients with CU who accepted a fish-free dietary regimen, the diagnostic performance of the in vivo and in vitro methods was calculated, and changes in specific IgE and BAT were evaluated with respect to clinical response.

RESULTS

A significant association between CU and A. simplex sensitization was found, with an overall prevalence of 75.4% in patients with CU (43/57) compared with 18% (4/22) and 10% (2/20) of the atopic and healthy controls, respectively (P < 0.0001). BAT (cut-off > 13%) had the highest sensitivity and specificity, with significantly better ability than specific IgE testing for the identification of A. simplex sensitization in patients with CU. During the 6-month follow-up, clinical improvement was seen in all patients, and specific IgE and BAT results decreased to normal values in 6/10 (60%) and 10/10 (100%) patients, respectively.

CONCLUSIONS

BAT can be considered a reliable new in vitro method to evaluate A. simplex hypersensitivity in patients with CU, supplementing standardized procedures in both diagnosis and follow-up.

Angioedema beyond histamine: an educational case series

Angioedema constitutes an important clinical problem that can cause significant morbidity and mortality. Correct management requires a prompt recognition and treatment of the acute event and identification of the underlying cause. Many cases are caused by non-allergic reactions and do not result from mediator release by degranulating mast cells and basophils, but are related to accumulation of plasma and tissue bradykinin. This case series aims primarily to describe some important causes of non-allergic bradykinin-induced angioedema. Particular emphasis is put on clinical particularities, differential diagnosis, diagnostic approach and correct therapeutic management, as bradykinin-mediated angioedema is unresponsive to antihistamines.

EAACI/GA(2)LEN task force consensus report: the autologous serum skin test in urticaria

Injection of autologous serum collected during disease activity from some patients with chronic spontaneous urticaria (CU) into clinically normal skin elicits an immediate weal and flare response. This observation provides a convincing demonstration of a circulating factor or factors that may be relevant to the understanding of the pathogenesis and management of the disease. This test has become known as the autologous serum skin test (ASST) and is now widely practised despite incomplete agreement about its value and meaning, the methodology and the definition of a positive response. It should be regarded as a test for autoreactivity rather than a specific test for autoimmune urticaria. It has only moderate specificity as a marker for functional autoantibodies against IgE or the high affinity IgE receptor (FcepsilonRI), detected by the basophil histamine release assay, but high negative predictive value for CU patients without them. It is usually negative in other patterns of CU, including those that are physically induced. Positive ASSTs have been reported in some subjects without CU, including those with multiple drug intolerance, patients with respiratory allergy and healthy controls, although the clinical implications of this are uncertain. It is essential that failsafe precautions are taken to ensure that the patient's own serum is used for skin testing and aseptic procedures are followed for sample preparation and handling. CU patients with a positive ASST (ASST(+)) are more likely to be associated with HLADR4, to have autoimmune thyroid disease, a more prolonged disease course and may be less responsive to H1-antihistamine treatment than those with a negative ASST (ASST(-)) although more evidence is needed to confirm these observations conclusively.

Update on chronic urticaria: focusing on mechanisms

PURPOSE OF REVIEW

This review discusses some of the recent advances in basic and clinical research focused on chronic urticaria. It is a concise summary of issues that occupied researchers' attention in the previous year, and it discusses a selection of novel findings that further our understanding of the pathomechanism of this disease.

RECENT FINDINGS

Particular consideration is given to the role of basophils, the coagulation cascade, fibrinolysis, and hormonal pathways in chronic urticaria pathogenesis. The description of clinical data is focused on prognostic issues, disease severity, and the effects of the disease on patients' quality of life.

SUMMARY

Mast cells are the key elements in chronic urticaria pathogenesis, whereas basophils should be regarded as bystanders and serve as biomarkers in some chronic urticaria subsets. The coagulation cascade, hormonal factors, and the psychological status of the patients seem to contribute substantially to the course and activity of the disease. Nonsedating second-generation antihistamines should be considered as first-line symptomatic treatment for chronic urticaria. Of note, the dosage should be increased up to four-fold if required before switching to second-line therapies.

Clinical and Laboratory Examinations in the Subgroups of Chronic Urticaria

BACKGROUND

The aetiology of chronic urticaria is heterogeneous. Physical urticaria (PU) is estimated at around 35%, autoimmune urticaria (AIU) at 25% and chronic idiopathic urticaria (CIU) at 35% of all chronic urticaria cases.

METHODS

Differences in clinical and laboratory parameters among AIU, PU and CIU groups were examined. AIU was diagnosed if the basophil CD63 assay was positive. Demographic data, severity of symptoms and association with allergic and autoimmune diseases were analysed by the aid of a questionnaire. Immunoassays were carried out and the effectiveness of therapy was also investigated.

RESULTS

Concerning the urticaria score, AIU patients had significantly higher total urticaria scores than patients with CIU (p = 0.013), dermatographic urticaria (p = 0.05) or cholinergic urticaria (p = 0.038). Between CIU and dermatographic urticaria and between CIU and cholinergic urticaria patients, we found insignificant differences in the urticaria score (p = 0.707 and p = 0.336, respectively). AIU was more frequently associated with autoimmune diseases in the personal history (p < 0.001) and with other types of urticaria in the family history (p < 0.001). Also, anti-thyroid antibodies were more frequently detected in the AIU group. Antihistamine therapy was less effective in the AIU group (12.8%) than in the PU (70.3%) and CIU groups (68.6%), but there were no significant differences between the CIU and PU groups regarding the effectiveness of antihistamine therapy.

CONCLUSION

The autoimmune subgroup represents the most severe form of chronic urticaria. On the other hand, there were no significant differences between the CIU and PU groups neither in urticaria scores nor in response to antihistamine therapy.

Chronic urticaria: what is new, where are we headed

Chronic urticaria can be defined as the occurrence of widespread daily or nearly daily wheals for at least 6 weeks, which may be accompanied by angioedema. It is a disease with a considerable impact on patients' quality of life. Furthermore, these patients may undergo extensive laboratory evaluations seeking a cause only to be frustrated when none is found. There is no curative treatment for this disorder and we do not understand the mechanisms that lead to the onset of disease. However, in recent years there have been significant advances in the understanding of some of the molecular mechanisms that cause cutaneous inflammation that is manifest as urticaria and angioedema. In this review we will summarize our recent contributions to this field and try to offer insights regarding future directions for research.