Effects of complement inactivation and IgG depletion on skin reactivity to autologous serum in chronic idiopathic urticaria

Chronic Spontaneous Urticaria: The Role and Relevance of Autoreactivity, Autoimmunity, and Autoallergy

Chronic spontaneous urticaria (CSU) is a frequent and often severely disabling disease. A large number of studies were performed during the last 2 decades to clarify its pathogenesis. These studies shed light on the underlying autoimmune mechanisms of CSU pathogenesis and have led us to understand that different mechanisms may exist and, sometimes, coexist behind the same clinical presentation. The present article reviews the meaning of the terms autoreactivity, autoimmunity, and autoallergy, which have been variably used over the years to define different endotypes of the disease. Furthermore, we discuss the methods potentially able to lead us to the correct classification of CSU patients.

A novel detection method for cross-linking of IgE-receptors by autoantibodies in chronic spontaneous urticaria

BACKGROUND

Autoantibodies (AAbs) against immunoglobulin E (IgE) antibodies (Abs) and their high-affinity receptor alpha subunits (FcεRIα) are key factors in the elicitation of type IIb autoimmune chronic spontaneous urticaria (type IIb aiCSU). In this study, we aimed to develop a new method to detect functional anti-FcεRIα and anti-IgE AAbs, which can crosslink the plural FcεRІα molecules and IgE Abs on the surface of mast cells and basophils, in sera from aiCSU patients using the amplified luminescence proximity homogeneous assay (Alpha).

METHODS

Sera were obtained from 14 aiCSU patients, as diagnosed by recurrent chronic spontaneous urticaria episodes and positive results for the autologous serum skin test and/or histamine release test (HRT). The AAbs to FcεRIα and IgE Abs were determined in sera from aiCSU patients using enzyme-linked immunosorbent assay (ELISA) and Alpha by cross-linking (AlphaCL) of IgE Abs and/or FcεRІα.

RESULTS

Serum anti-FcεRIα and anti-IgE AAb levels were not significantly different between aiCSU patients and healthy subjects in ELISA. Anti-FcεRIα AAbs were detected in 10 of 14 aiCSU patients who displayed positive (5/5) and negative (5/9) results in the HRT for anti-FcεRIα AAbs by AlphaCL, whereas no signals were observed in healthy subjects. Additionally, anti-IgE AAbs were detected in two of four aiCSU patients who displayed positive results in the HRT for anti-IgE AAbs.

CONCLUSIONS

A new assay method using AlphaCL can detect anti-FcεRIα and anti-IgE AAbs with FcεRIα- and IgE-crosslinking abilities in sera from aiCSU patients. This simple and practical assay method may be available as a diagnostic tool for urticaria patients.

Association Between Helicobacter pylori-Negative Peptic Ulcer Disease and Chronic Urticaria: A Retrospective Observational Study

Objective

The association between peptic ulcer disease (PUD) and chronic urticaria (CU) is rarely examined in individuals without Helicobacter pylori infection. The study aimed to investigate the association between Helicobacter pylori-negative PUD and CU.

Methods

Patients without Helicobacter pylori infection were retrospectively enrolled from those who visited the clinic or were admitted to the ward of the dermatological department with recent gastroscopy and Helicobacter pylori testing in a tertiary hospital between 2015 and 2019. After categorizing them as patients with and without PUD, we used propensity score matching to identify a cohort of PUD and a control cohort at a ratio of 1:2. CU was determined by examining medical records of the two cohorts, and logistic regression analyses were used to evaluate the association between PUD and CU with or without adjusting for covariates.

Results

We included 40 patients with PUD as the PUD cohort and 80 patients without PUD as the control cohort, between which there were no significant differences in patient characteristics, including age, sex, and several comorbidities (P all >0.05). Among the PUD cohort, 25.00% (10/40) of them were with CU, which was significantly higher than that in the control cohort 8.75% (7/80, P = 0.016). Results of logistic regression analyses showed PUD was significantly associated with increased risk of CU (odds ratio (OR) 3.48, 95% confidence interval (CI) 1.21–9.99, P = 0.021), which was consistent with that after adjusted for potential confounding factors (OR 3.77, 95% CI 1.24–11.45, P = 0.019).

Conclusion

Helicobacter pylori-negative PUD is associated with increased risk of CU.

Rationale for the autologous serum skin test in acute versus chronic urticaria

Introduction

Autologous serum skin test (ASST) is a rapid, in-vivo clinical test to detect functional autoantibodies in patients with chronic spontaneous urticaria (CSU), but the rationale for its use in acute urticaria (AU) is unknown.

Aim

To evaluate the efficacy of ASST among patients with AU or CSU.

Material and methods

Treatment-naïve adult (age ≥ 18 years) patients with a diagnosis of AU (< 6 weeks’ duration) and CSU were enrolled prospectively in a cross-sectional study. Healthy age- and sex-matched subjects served as controls. Besides a detailed history and physical examination, ASST, total immunoglobulin E (IgE), freeT3 (fT3), freeT4 (fT4), anti-thyroglobulin, and anti-TPO levels were assessed in all subjects.

Results

Of 101 subjects, mean age was 34.35 ±12.68 years and the study comprised 58.4% of females with no difference between AU (n = 27), CSU (n = 46), and control groups (n = 28). The ratio of positivity in ASST was similar between AU (25.9%) and CSU groups (21.7%), but higher than in controls (10.7%, p = 0.33 for all). The ratio of patients with high total IgE levels (> 100 IU/ml) in AU (85.2%) and CSU (65.2%) groups was similar (p = 0.06), but significantly higher than in the control group (10.7%) (p< 0.001 and p< 0.001). The CSU group had significantly higher abnormal thyroid test results (45.7%) than AU (14.8%) and control groups (3.6%) (p = 0.01 and p< 0.001), whereas patients with clinically diagnosed thyroiditis were only in the CSU group (6.5%). In logistic regression analysis, there was no relation found among the possible risk factors for ASST, even if analysed separately as AU, CSU and control groups.

Conclusions

Even though thyroid function test levels were found to be related with CSU, and total IgE was associated with urticaria, ASST was found to be of importance. This study confirms that ASST was insufficient to demonstrate autoimmunity and acute-chronic urticaria nature. Further tests indicating auto-antibodies in AU and CSU are needed.

Clinicoepidemiologic Features of Chronic Spontaneous Urticaria in Patients with Elevated Plasma D-Dimer Levels versus those without It: A Case-Control Cross-Sectional Study of 100 Indian Patients

Background

Activated coagulation cascade is implicated in urticaria pathogenesis marked by high plasma D-dimer, a marker of fibrinolysis, levels correlating with high urticaria activity score (UAS) and poor therapeutic outcome.

Methods

Quantitative plasma D-dimer levels and coagulation parameters in 100 (male:female ratio 1:3) Indian patients with chronic spontaneous urticaria and age- and gender-matched healthy controls were compared. The clinicoepidemiologic features of chronic urticaria were then compared among patients with normal (≤0.2 mg/L) and elevated (≥0.3 mg/L) plasma D-dimer levels.

Results

Plasma D-dimer in 23% patients and 4% controls and prothrombin time and activated partial thromboplastin time in 63% and 5% patients, respectively, were significantly higher compared with 58% and 1% of controls, respectively. About 18 of 72 (25%) patients with high UAS of ≥16-42 were compared with 5 of 28 (17.8%) patients with UAS7 of ≤15. Patients with elevated plasma D-dimer levels had significantly more systemic symptoms (86.9% vs. 81.8%) compared with patients with normal plasma D-dimer levels.

Conclusion

A subset of patients with chronic urticaria have elevated plasma D-dimer levels and exhibit higher UAS7 and systemic symptoms that may influence long-term prognosis and therapeutic choices. Small number of patients, a cross-sectional nature of study, lack of treatment outcome measures, information on self-medication, and unavailability of specific parameters for coagulation pathway activation remain few limitations of this study.

Management of chronic urticaria in children: a clinical guideline

The aim of this guidance is to provide recommendations to clinicians and other interested parties on chronic urticaria in children. The Italian Society for Pediatrics (SIP), the Italian Society for Allergy and Immunology (SIAIP), the Italian Society for Pediatric dermatology (SIDerP) convened a multidisciplinary panel that prepared clinical guidelines for diagnosis and management of chronic urticaria in childhood. Key questions on epidemiology, natural history, diagnosis, and management were developed. The literature was systematically searched and evaluated, recommendations were rated and algorithms for diagnosis and treatment were developed. The recommendations focus on identification of diseases and comorbidities, strategies to recognize triggering factors, improvement of treatment by individualized care.

Differentiation between control subjects and patients with chronic spontaneous urticaria based on the ability of anti-IgE autoantibodies (AAbs) to induce FcεRI crosslinking, as compared to anti-FcεRIα AAbs

BACKGROUND

The reported prevalences of IgG autoantibodies (AAbs) to FcεRIα and IgE in sera from patients with chronic spontaneous urticaria (CSU) have varied, and these AAbs are also often observed in healthy control subjects. Regarding the histamine release activity of purified IgG from patients with CSU, the number of examined patients has been small. Thus, we sought to determine the prevalence and FcεRI crosslinking ability of these AAbs in a large number of patients with CSU and non-atopic control (NC) subjects.

METHODS

We compared the concentrations of anti-IgE and anti-FcεRIα AAbs and the abilities of these AAbs to cause FcεRI aggregation in patients with CSU (n = 134) and NC subjects (n = 55) using ELISA and an in vitro elicitation test, respectively.

RESULTS

The concentration of anti-IgE AAbs was significantly different between the NC subjects and the CSU patients (P < 0.0001, cutoff value: 0.558 μg/mL), whereas the concentration of anti-FcεRIα AAbs was not. A significant difference in the duration of illness was noted between patients with lower and those with higher concentrations of anti-IgE AAbs relative to the cutoff value. The abilities of anti-IgE AAbs, but not anti-FcεRIα AAbs, to induce FcεRI crosslinking were significantly higher in CSU patients than in NC subjects (P = 0.0106).

CONCLUSIONS

In the Japanese population of CSU patients studied, the ability of the anti-IgE AAbs to induce FcεRI crosslinking differed significantly between NC subjects and CSU patients, suggesting the involvement of anti-IgE AAbs in the pathogenesis of CSU in the Japanese population.

Causal Relationship Between Anti-TPO IgE and Chronic Urticaria by In Vitro and In Vivo Tests

PURPOSE

Immunoglobulin (Ig) E autoantibodies against thyroid antigens such as thyroid peroxidase (TPO) have been demonstrated in chronic spontaneous urticaria (CSU) patients in higher frequency than healthy subjects. However, if these IgE autoantibodies can trigger urticaria is still a matter of study. The aim of this study was to investigate the relationship between concomitant IgE autoantibodies against thyroid antigens in CSU.

METHODS

Patients with CSU, healthy subjects and patients with autoimmune thyroid disease (ATD) were recruited. Total IgE and specific anti-TPO IgE and IgG were assessed in all subjects. The basophil activation test and skin tests with TPO were performed to demonstrate whether this antigen could selectively induce urticaria reaction in subjects with positive anti-TPO IgE.

RESULTS

Anti-TPO IgE was present in all 3 groups (CSU: 34.0%, ATD: 16.6%, healthy subjects: 8.1%). Anti-TPO IgE levels were higher in CSU patients, whereas anti-TPO IgG were higher in ATD patients. After exposure to TPO, CD203c expression from patients with CSU and anti-TPO IgE significantly increased in comparison to the other groups; 33.0% vs. 14.0% in ATD patients and 9.0% in control subjects (P < 0.05). Skin reactions with TPO were higher in patients with CSU according to the intradermal (CSU: 18.0%, ATD: 3.3%, control: 8.0%) and skin prick tests (12.0%, 0%, 0%, respectively). Passive transfer of anti-TPO IgE from a CSU patient to the skin of control subjects without anti-TPO IgE induced a positive skin reaction.

CONCLUSIONS

Anti-TPO IgE is not a specific biomarker for CSU. However, IgE against TPO plays a pathogenic role in inducing effector cell activation and skin exacerbation in some patients with CSU.

Aspergillus Cell Wall Chitin Induces Anti- and Proinflammatory Cytokines in Human PBMCs via the Fc-γ Receptor/Syk/PI3K Pathway

Chitin is an important cell wall component of Aspergillus fumigatus conidia, of which hundreds are inhaled on a daily basis. Previous studies have shown that chitin has both anti- and proinflammatory properties; however the exact mechanisms determining the inflammatory signature of chitin are poorly understood, especially in human immune cells. Human peripheral blood mononuclear cells were isolated from healthy volunteers and stimulated with chitin from Aspergillus fumigatus Transcription and production of the proinflammatory cytokine interleukin-1β (IL-1β) and the anti-inflammatory cytokine IL-1 receptor antagonist (IL-1Ra) were measured from the cell culture supernatant by quantitative PCR (qPCR) or enzyme-linked immunosorbent assay (ELISA), respectively. Chitin induced an anti-inflammatory signature characterized by the production of IL-1Ra in the presence of human serum, which was abrogated in immunoglobulin-depleted serum. Fc-γ-receptor-dependent recognition and phagocytosis of IgG-opsonized chitin was identified as a novel IL-1Ra-inducing mechanism by chitin. IL-1Ra production induced by chitin was dependent on Syk kinase and phosphatidylinositol 3-kinase (PI3K) activation. In contrast, costimulation of chitin with the pattern recognition receptor (PRR) ligands lipopolysaccharide, Pam3Cys, or muramyl dipeptide, but not β-glucan, had synergistic effects on the induction of proinflammatory cytokines by human peripheral blood mononuclear cells (PBMCs). In conclusion, chitin can have both pro- and anti-inflammatory properties, depending on the presence of pathogen-associated molecular patterns and immunoglobulins, thus explaining the various inflammatory signatures reported for chitin.

IMPORTANCE

Invasive aspergillosis and allergic aspergillosis are increasing health care problems. Patients get infected by inhalation of the airborne spores of Aspergillus fumigatus A profound knowledge of how Aspergillus and its cell wall components are recognized by the host cell and which type of immune response it induces is necessary to develop target-specific treatment options with less severe side effects than the treatment options to date. There is controversy in the literature about the receptor for chitin in human cells. We identified the Fc-γ receptor and Syk/PI3K pathway via which chitin can induce anti-inflammatory immune responses by inducing IL-1 receptor antagonist in the presence of human immunoglobulins but also proinflammatory responses in the presence of bacterial components. This explains why Aspergillus does not induce strong inflammation just by inhalation and rather fulfills an immune-dampening function. While in a lung coinfected with bacteria, Aspergillus augments immune responses by shifting toward a proinflammatory reaction.

Pattern recognition pathways leading to a Th2 cytokine bias in allergic bronchopulmonary aspergillosis patients

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is characterised by an exaggerated Th2 response to Aspergillus fumigatus, but the immunological pathways responsible for this effect are unknown.

OBJECTIVE

The aim of this study was to decipher the pattern recognition receptors (PRRs) and cytokines involved in the Aspergillus-specific Th2 response and to study Aspergillus-induced responses in healthy controls and ABPA patients.

METHODS

Peripheral blood mononuclear cells (PBMCs) were stimulated with heat-killed Aspergillus conidia, various other pathogens, or PRR ligands. PRRs and cytokine pathways were blocked with PRR-blocking reagents, anti-TNF (Etanercept or Adalimumab), IL-1Ra (Anakinra) or IFNγ (IFN-gamma). ELISA and FACS were used to analyse cytokine responses.

RESULTS

Aspergillus was the only pathogen that stimulated the Th2 cytokines IL-5 and IL-13, while Gram-negative bacteria, Gram-positive bacteria, Candida albicans, chitin, β-glucan or Toll-like receptor (TLR) ligands did not. Depletion of CD4(+) cells abolished IL-13 production. Blocking complement receptor 3 (CR3) significantly reduced IL-5 and IL-13, while blocking TLR2, TLR4 or dectin-1 had no effect. ABPA patients displayed increased Aspergillus-induced IL-5 and IL-13 and decreased IFNγ production compared with healthy controls. All biological agents tested showed the capability to inhibit Th2 responses, but also decreased Aspergillus-induced IFNγ.

CONCLUSIONS AND CLINICAL RELEVANCE

Aspergillus conidia are unique in triggering Th2 responses in human PBMCs, through a CR3-dependent pathway. ABPA patients display a significantly increased Aspergillus-induced Th2/Th1 ratio that can be modulated by biologicals. These data provide a rationale to explore IFNγ therapy in ABPA as a corticosteroid-sparing treatment option, by dampening Th2 responses and supplementing the IFNγ deficiency at the same time.

Pathogenesis of chronic urticaria: an overview

The pathogenesis of chronic urticaria is not well delineated and the treatment is palliative as it is not tied to the pathomechanism. The centrality of mast cells and their inappropriate activation and degranulation as the key pathophysiological event are well established. The triggering stimuli and the complexity of effector mechanisms remain speculative. Autoimmune origin of chronic urticaria, albeit controversial, is well documented. Numerical and behavioral alterations in basophils accompanied by changes in signaling molecule expression and function as well as aberrant activation of extrinsic pathway of coagulation are other alternative hypotheses. It is also probable that mast cells are involved in the pathogenesis through mechanisms that extend beyond high affinity IgE receptor stimulation. An increasing recognition of chronic urticaria as an immune mediated inflammatory disorder related to altered cytokine-chemokine network consequent to immune dysregulation resulting from disturbed innate immunity is emerging as yet another pathogenic explanation. It is likely that these different pathomechanisms are interlinked rather than independent cascades, acting either synergistically or sequentially to produce clinical expression of chronic urticaria. Insights into the complexities of pathogenesis may provide an impetus to develop safer, efficacious, and targeted immunomodulators and biological treatment for severe, refractory chronic urticaria.

Chronic spontaneous urticaria: etiology and pathogenesis

Urticaria affects individuals of all ages and is commonplace. Nearly 1 in 5 individuals will experience an episode of urticaria in their lifetime, while the chronic form of disease has an estimated annual prevalence of approximately 1% of the population. Given the similarity of chronic urticaria symptoms to those seen in patients suffering an allergic reaction, the condition often leads to a search for an external cause. In most cases, no external trigger factor is identified. At present several theories of pathogenesis exist, none of which is firmly established.

Correlation between plasma D-dimer levels and the severity of patients with chronic urticaria

Background

Beside autoimmunity, coagulation pathway is also involved in the pathogenesis of chronic urticaria (CU). Previous studies showed that plasma D-dimer levels paralleled the severity of the disease. To date, there are no data concerning D-dimer level in Thai patients with CU.

Objective

This study aimed to find the relationship between plasma D-dimer levels and the disease severity of Thai CU patients. The secondary objective is to analyze plasma D-dimer level in each group of patients who performed autologous plasma skin testing (APST) and autologous serum skin testing (ASST).

Methods

We retrospectively reviewed case record forms of chronic idiopathic urticaria (CIU) patients aged at least 18 years in Skin Allergy Clinic, Siriraj Hospital Mahidol University, Bangkok, during June 2008 to June 2011.

Results

Of 120 patients, plasma D-dimer level was abnormal in 58 patients (48.3%). The study showed statistically significant positive correlation between disease severity and plasma D-dimer level (p < 0.05, r = 0.537). There was no statistically significant difference in plasma D-dimer level between APST positive and negative groups, and also between ASST positive and negative groups. In APST negative group, plasma D-dimer level was elevated in 29 patients (47.5%) and correlated with disease severity.

Conclusion

This study showed elevated plasma D-dimer levels in nearly half of Thai patients with CIU. There was a positive correlation between plasma D-dimer levels and the severity of disease activity. Investigation for plasma D-dimer level may be an alternative way to evaluate disease severity in patients with CIU.

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.

Diagnosis and treatment of urticaria and angioedema: a worldwide perspective

: Urticaria and angioedema are common clinical conditions representing a major concern for physicians and patients alike. The World Allergy Organization (WAO), recognizing the importance of these diseases, has contributed to previous guidelines for the diagnosis and management of urticaria. The Scientific and Clinical Issues Council of WAO proposed the development of this global Position Paper to further enhance the clinical management of these disorders through the participation of renowned experts from all WAO regions of the world. Sections on definition and classification, prevalence, etiology and pathogenesis, diagnosis, treatment, and prognosis are based on the best scientific evidence presently available. Additional sections devoted to urticaria and angioedema in children and pregnant women, quality of life and patient-reported outcomes, and physical urticarias have been incorporated into this document. It is expected that this article will supplement recent international guidelines with the contribution of an expert panel designated by the WAO, increasing awareness of the importance of urticaria and angioedema in medical practice and will become a useful source of information for optimum patient management worldwide.

Chronic spontaneous urticaria: an autoimmune disease? A revision of the literature

The cause of chronic spontaneous urticaria has been an enigma for decades, but the recognition of functional autoantibodies in some patients with the spontaneous chronic urticaria has opened up a new concept of autoimmune urticaria. Clinical and laboratory features are in keeping with an autoimmune aetiology for many patients with otherwise inexplicable disease, but there is still debate about the importance of functional autoantibodies in the disease pathogenesis, how to test them and the clinical implications for treatment and prognosis. This review will look at the evidence for there being an autoimmune subset of urticaria, the strengths and weaknesses of the available tests in current use.

Activation of blood coagulation in autoimmune skin disorders

The immune system and blood coagulation are simultaneously activated in several inflammatory systemic disorders, such as lupus erythematosus, rheumatoid arthritis and inflammatory bowel diseases. Proinflammatory cytokines, such as IL-6 and TNF-alpha, induce the expression of tissue factor, the main initiator of blood coagulation. Activated proteases of coagulation in turn act on protease-activated receptors, inducing the expression of various proinflammatory cytokines. This cross-talk between inflammation and coagulation amplifies and maintains the activation of both systems. This review focuses on three skin disorders: chronic urticaria (CU), which is considered autoimmune in approximately 50% of cases, bullous pemphigoid (BP), which is the prototype of autoimmune blistering disease, and psoriasis, which is an immune-mediated dermatitis. In CU, the activation of coagulation, which is due to the involvement of eosinophils and tissue factor pathways with the generation of thrombin, has local implications by increasing dermal vascular permeability. Preliminary data indicate that anticoagulant treatment with heparin and warfarin may be effective in reducing the symptoms of this disorder. In BP, the activation of coagulation seems to have both local and systemic implications. Locally, eosinophils and thrombin participate in bulla formation and tissue damage; systemically, the activation of coagulation may explain the increased thrombotic risk observed in these patients. In psoriasis, the activation of coagulation seems to be mainly systemic, potentially contributing to the increased cardiovascular risk associated with this disease.

Activation of blood coagulation in chronic urticaria: pathophysiological and clinical implications

Chronic urticaria (CU) is a skin disorder characterized by the recurrent eruption of short-lived wheals accompanied by redness and itching for at least 6 weeks. The wheals can be associated with angioedema. CU is considered an autoimmune disease in about 50% of cases with the presence of circulating histamine releasing autoantibodies mainly directed against the high affinity IgE receptor FcepsilonRI on mast cells and basophils or against IgE. In several CU cases regarded as idiopathic; the actual pathophysiological mechanisms are still unknown. Some patients with CU do not respond to antihistamines and require the use of systemic steroids or cyclosporin, which are, however, not always effective. In CU, several investigators have demonstrated the activation of coagulation that is due to the involvement of eosinophils and a tissue factor pathway with generation of thrombin potentially contributing to an increased vascular permeability. CU patients often present with elevation of coagulation and fibrinolysis markers, such as prothrombin fragment F1+2 and D: -dimer, which correlate with the disease severity. Preliminary data indicate that anticoagulant treatment with heparin and warfarin may be effective in reducing the symptoms of this disorder. Taken together, all these findings provide the rationale for proposing clinical trials on the use of anticoagulant drugs as adjuvant treatment in CU patients.

Plasma levels and skin-eosinophil-expression of vascular endothelial growth factor in patients with chronic urticaria

BACKGROUND

Although chronic urticaria (CU) is often regarded as autoimmune in nature, only less than 50% of sera from CU patients contain histamine-releasing autoantibodies. This suggests that other factors may contribute to its pathogenesis. We evaluated the possible involvement of vascular endothelial growth factor (VEGF), one of the major mediators of vascular permeability, in CU.

METHODS

Eighty consecutive adult patients with CU and 53 healthy subjects were studied. VEGF and prothrombin fragment F(1+2) were measured by enzyme immunoassays. Autologous plasma skin test (APST) was performed in CU patients and, in six of them, skin biopsy specimens were taken from wheals to evaluate the immunohistochemical expression of VEGF and eosinophil cationic protein (ECP).

RESULTS

Plasma VEGF concentrations were higher in CU patients (8.00 +/- 0.90 pmol/l) than in controls (0.54 +/- 0.08 pmol/l) (P = 0.0001) and tended to parallel both the severity of CU and to correlate with F(1+2) levels. APST was positive in 85.1% of patients. VEGF concentration was significantly higher in APST-positive than in APST-negative patients (P = 0.0003). Immunohistochemically, all specimens from patients with CU showed a strong expression of VEGF (P = 0.002) that colocalized with ECP, a classic eosinophil marker.

CONCLUSIONS

VEGF plasma levels are elevated in CU and parallel the disease severity. This supports a possible role of this molecule in CU pathophysiology. Eosinophils are the main cellular source of VEGF in CU lesional skin.

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.

Reactivity to autologous serum skin test and relationship with complement levels in chronic idiopathic urticaria and angio-oedema

BACKGROUND

A role for complement in autoantibody-mediated histamine release in urticaria has been suggested but not proven in vivo. Aim. To study serum complement levels in patients with chronic idiopathic urticaria (CIU) and to determine whether there was a relationship with autologous serum skin test (ASST) reactivity.

METHODS

We recruited 35 patients with CIU. Complement (C3, C4) levels and ASST were measured in all patients; additional investigations were undertaken dependent on history and examination.

RESULTS

Complement concentrations were outside the population reference intervals in 19/35 patients, with low C3 noted in 3/35 and low C4 in 18/35. Of 12 patients with a positive ASST, 7 had low complement levels, and 12/23 with a negative ASST had low complement levels. Patients with a positive ASST had a median C3 of 1.24 g/L (range 0.35-1.51) compared with a median of 1.25 g/L in those with a negative ASST (P = 0.36), and a median C4 of 0.20 g/L (range 0.185-0.452) in those with a positive ASST compared with 0.18 g/L in those with a negative ASST (P = 0.88).

CONCLUSIONS

We conclude that both a reduction in C4 and positive ASST are common in CIU and although these immunological abnormalities often coexist, there is no clear relationship between them. Other components of the complement system may be worth exploring.

New concepts in chronic urticaria

Chronic urticaria is a common skin disease without a clear etiology in the vast majority of cases. The similarity of symptoms and lesion pathology to allergen-induced skin reactions supports the idea that skin mast cell and blood basophil IgE receptor activation is involved; however, no exogenous allergen trigger has been identified. The presence of serum IgG autoantibodies targeting IgE or the IgE receptor in approximately 40% of CIU cases supports the theory of an autoimmune basis for the disease. However, issues remain with the assays to detect autoantibodies among other serum factors, the relationship of autoantibodies to CIU disease activity, and the occurrence of autoantibodies in healthy subjects. Other studies have identified altered IgE receptor degranulation that reverts in disease remission and is accompanied by changes in signaling molecule expression and function in mast cells and basophils in active CIU subjects. The arrival of therapies targeting IgE and the IgE receptor pathway elements has potential use in CIU.

Pathophysiology of chronic urticaria

OBJECTIVE

To review the literature on the pathogenesis of chronic urticaria (excluding physical urticaria).

DATA SOURCES

PubMed was searched using the keywords urticaria and either chronic or autoimmune or pathogenesis for articles published from January 1972 to June 2007. All searches were limited to the English language. References from review articles on chronic urticaria were also considered for inclusion in this review.

STUDY SELECTION

The authors selected relevant and current sources for inclusion in this review.

RESULTS

No concise pathogenic mechanism has been identified for all cases of chronic urticaria, although evidence for a serologic mediator that may be autoimmune in nature has been identified in many cases. The activation of basophils and/or mast cells is a central feature in any theory proposed to explain this troubling disease.

CONCLUSION

Further research is needed to better define the mechanism or mechanism(s) responsible for the development of chronic urticaria. Such research will lead to more effective and possibly even curative treatments.

Coagulation cascade and fibrinolysis in patients with multiple-drug allergy syndrome

BACKGROUND

Previous studies have shown that patients with multiple-drug allergy syndrome (MDAS) frequently have positive autologous serum skin test results, similar to patients with chronic urticaria (CU). Recent investigations have found that patients with CU show signs of thrombin generation and activation of the tissue factor pathway of the coagulation cascade.

OBJECTIVE

To study thrombin generation and fibrinolysis in patients with MDAS.

METHODS

Nine patients with MDAS underwent autologous plasma skin testing (APST) and measurement of plasma prothrombin fragment F(1 + 2) and D-dimer levels. Furthermore, the basophil histamine-releasing activity of plasma from patients with MDAS was evaluated. Plasma samples from 74 healthy control subjects and 13 patients with CU were used as negative and positive controls, respectively.

RESULTS

All 9 patients with MDAS had positive APST results, and 7 showed elevated plasma levels of fragment F(1 + 2). In patients with MDAS, the median F(1 + 2) level (339 pmol/L; interquartile range [IQR], 250-401 pmol/L) significantly exceeded that in healthy controls (159 pmol/L; IQR, 123-196 pmol/L) (P = .001) but did not significantly differ from that in controls with CU (292 pmol/L; IQR, 182-564 pmol/L; P = .38). Plasma D-dimer levels were normal in all the patients with MDAS and were significantly lower than in controls with CU (P = .009). Finally, the histamine-releasing activity of plasma from patients with MDAS was significantly increased and correlated with F(1+ 2) levels (r = 0.68; P = .04).

CONCLUSION

Positive APST results and thrombin generation indicate a common physiopathologic background in MDAS and CU. The lower D-dimer levels suggest that fibrinolysis occurs less intensely in MDAS than in CU.

Complement is an essential component of the immune response to adeno-associated virus vectors

Adeno-associated virus (AAV) vectors are associated with relatively mild host immune responses in vivo. Although AAV induces very weak innate immune responses, neutralizing antibodies against the vector capsid and transgene still occur. To understand further the basis of the antiviral immune response to AAV vectors, studies were performed to characterize AAV interactions with macrophages. Primary mouse macrophages and human THP-1 cells transduced in vitro using an AAV serotype 2 (AAV2) vector encoding green fluorescent protein did not result in measurable transgene expression. An assessment of internalized vector genomes showed that AAV2 vector uptake was enhanced in the presence of normal but not heat-inactivated or C3-depleted mouse/human serum. Enhanced uptake in the presence of serum coincided with increased macrophage activation as determined by the expression of NF-kappaB-dependent genes such as macrophage inflammatory protein 2 (MIP-2), interleukin-1beta (IL-1beta), IL-8, and MIP-1beta. AAV vector serotypes 1 and 8 also activated human and mouse macrophages in a serum-dependent manner. Immunoprecipitation studies demonstrated the binding of iC3b complement protein to the AAV2 capsid in human serum. AAV2 did not activate the alternative pathway of the complement cascade and lacked cofactor activity for factor I-mediated degradation of C3b to iC3b. Instead, our results suggest that the AAV capsid also binds complement regulatory protein factor H. In vivo, complement receptor 1/2- and C3-deficient mice displayed impaired humoral immunity against AAV2 vectors, with a delay in antibody development and significantly lower neutralizing antibody titers. These results show that the complement system is an essential component of the host immune response to AAV.

Urtikaria

A number of recent epidemiologic and experimental studies have enhanced our knowledge of the etiology and pathogenesis of urticaria. In addition, new instruments for diagnosing urticaria variants and for assessing the quality of life in urticaria patients have been developed. Finally, several clinical trials have demonstrated the efficacy of novel treatment approaches for urticaria, while other therapeutic concepts are under development. Here, we provide a brief review of selected findings from these recent reports and a discussion of their relevance for clinical practice.

The autologous serum skin test in a cohort of chronic idiopathic urticaria patients compared to respiratory allergy patients and healthy individuals

BACKGROUND

A positive autologous serum skin test (ASST) is considered to reflect the presence of anti-FceRI and/or anti-IgE autoantibodies that are capable of activating mast and basophil cell degranulation. The ASST is regarded as a reliable in vivo test in chronic idiopathic urticaria (CIU) patients, with diagnostic, therapeutic and prognostic implications. However, positive ASST results have also occasionally been demonstrated in patients with other diseases and in healthy subjects.

OBJECTIVE

To evaluate the specificity and sensitivity of the ASST in a cohort of CIU patients compared to a cohort of respiratory-allergic patients and a group of normal individuals.

METHODS

ASST was performed in a cohort of 116 subjects, 47 subjects with seasonal allergic rhinitis, 32 respiratory-symptom-free CIU patients, and 37 healthy individuals.

RESULTS

The results were compared statistically to those of the CIU patients. The intradermal injection of autologous serum induced a weal and flare reaction in 17/32 (53.1%) CIU patients; 14/47 (29.8%) patients with seasonal allergic rhinitis (P=0.06) and in 15/37 (40.5%) of the healthy controls (P=0.34). The sensitivity and specificity of the ASST in the CIU patients and the seasonal allergic rhinitis patients was 53 and 28%, respectively. When comparing the CIU patients with the healthy controls the sensitivity and specificity was 55 and 31%, respectively. The positive and negative predictive values of the ASST when comparing CIU patients with healthy controls were 53 and 59.5%, respectively. The positive and negative predictive values of the ASST in the CIU patients compared to seasonal allergic rhinitis patients were 53 and 70%, respectively.

CONCLUSION

The relatively low sensitivity and specificity of the ASST in the CIU patients compared to the seasonal allergic rhinitis patients and healthy controls warrants a more critical interpretation of the ASST in chronic idiopathic urticaria.

Autologous whole blood injections to patients with chronic urticaria and a positive autologous serum skin test: a placebo-controlled trial

BACKGROUND

Patients with chronic urticaria (CU) frequently exhibit positive skin test reactions to autologous serum (ASST). Therapies aimed at inducing tolerance to circulating histamine-releasing factors in ASST+ CU patients, e.g. by treatment with autologous whole blood (AWB), have not yet been tested.

OBJECTIVE

To test whether ASST+ CU patients can benefit from repeated low-dose intramuscular injections of AWB.

METHODS

We characterized CU severity and duration, anti-Fc(epsilon)RI and anti-IgE expression, use of antihistamines, and quality of life in 56 CU patients (ASST+: 35, ASST-: 21) and assessed the therapeutic effects of 8 weekly AWB injections in a randomized, placebo-controlled, single-blind, parallel-group trial.

RESULTS

Numbers, size, intensity, and/or duration of CU symptoms, quality of life, as well as expression of anti-Fc(epsilon)RI or anti-IgE were similar in ASST+ and ASST- CU patients. However, CU in ASST+ patients was of longer duration and required markedly more antihistaminic medication. Interestingly, ASST+ patients, but not ASST- patients, showed significantly (1) reduced CU activity, (2) decreased use of antihistamines, and (3) improved quality of life after AWB treatment. Placebo treatment was ineffective in both groups, but differences of AWB and placebo treatment responses did not achieve statistical significance in either group, most likely due to the limited number of patients treated.

CONCLUSION

Our findings suggest that ASST+ CU is clinically different from other CU subforms and that ASST+ CU patients can benefit from AWB therapy.

Emerging drugs for chronic urticaria

Chronic urticaria (CU), with or without angioedema, is a frequent disorder defined as the occurrence of pruritic wheals for > 6 weeks. Studies carried out in the last two decades showed that the origin of the disease is autoimmune in up to 50% of cases. Currently available treatments include antihistamines, corticosteroids and ciclosporin; recently, leukotriene receptor antagonists proved effective in a subset of patients as well. For patients with an unremitting and extremely severe disease unresponsive to standard treatments, plasmapheresis and immunosuppressive drugs have been successfully attempted. Recent findings that the autologous plasma skin test scores positive in nearly all patients and that plasmas from patients with both autoimmune and 'idiopathic' chronic urticaria are frequently characterised by signs of thrombin activation (plasma levels of prothrombin fragment F(1.2) are significantly increased) suggest that clotting cascade might be somehow involved in the pathogenesis of CU. These findings put under a new light some rather sparse studies of the effect of drugs active on the coagulation system (heparin and oral anticoagulants) in patients with CU.

Plasma of patients with chronic urticaria shows signs of thrombin generation, and its intradermal injection causes wheal-and-flare reactions much more frequently than autologous serum

BACKGROUND

Several aspects of the pathogenesis of chronic urticaria (CU) remain contradictory. Autologous serum skin tests (ASSTs) and in vitro histamine release assays seem to look into distinct aspects of the disease, and the specificity of ASST has been questioned.

OBJECTIVE

We compared the autologous plasma skin test (APST) with ASST to detect autoreactivity in patients with CU. The clotting process was investigated as well by measuring in vivo thrombin generation.

METHODS

A total of 96 adults with CU underwent ASST; 71 of them underwent APST with Na citrate-anticoagulated plasma. Prothrombin fragment 1+2 plasma levels were measured by a sandwich ELISA in Na citrate-anticoagulated plasmas from 28 patients and 27 controls.

RESULTS

Fifty-one of 96 (53%) patients scored positive on ASST, whereas 61 of 71 (86%) patients scored positive on APST (21/30 [70%] ASST-negative and 40/41 [98%] ASST-positive). Plasma prothrombin fragment 1+2 was higher in patients than controls (3.06 [SD 3.36] vs 0.80 [0.34]; P < .001) and in ASST-positive/APST-positive than in ASST-negative/APST-positive patients (3.89 [SD 3.68] vs 1.33 [1.64]; P = 0.058) and was directly related to urticaria severity (r = 0.37; P < .05).

CONCLUSION

Most patients with CU are positive on APST-Na citrate. CU is associated with the generation of thrombin, a serine protease able to activate mast cells and to cause relevant increase in permeability of endothelium. APST and ASST only partially depend on the presence of circulating antibodies to FcepsilonRI or to IgE.

CLINICAL IMPLICATIONS

These findings provide new insights into the pathogenesis of CU and suggest new therapeutic opportunities for treating this disease.

Neutrophils interact with adenovirus vectors via Fc receptors and complement receptor 1

Neutrophils are effectors of the innate immune response to adenovirus vectors. Following the systemic administration of Cy2-labeled AdLuc in mice, flow cytometry and PCR analysis of liver leukocytes revealed that 25% of recruited neutrophils interacted with adenovirus vectors. In vitro, flow cytometry of human neutrophils incubated with Cy2-labeled AdLuc also demonstrated a significant interaction with adenovirus vectors. Fluorescence and electron microscopy confirmed vector internalization by neutrophils. The AdLuc-neutrophil interaction reduced vector transduction efficiency by more than 50% in coincubation assays in epithelium-derived cells. Adenovirus vector uptake by neutrophils occurred independently of coxsackievirus adenovirus receptor (CAR) and capsid RGD motifs, since neutrophils do not express CAR and uptake of the RGD-deleted vector AdL.PB* was similar to that of AdLuc. Furthermore, both AdLuc and AdL.PB* activated neutrophils and induced similar degrees of L-selectin shedding. Neutrophil uptake of AdLuc was dependent on the presence of complement and antibodies, since the interaction between AdLuc and neutrophils was significantly reduced when they were incubated in immunoglobulin G-depleted or heat-inactivated human serum. Blocking of complement receptor 1 (CD35) but not complement receptor 3 (CD11b/CD18) significantly reduced neutrophil uptake of AdLuc. Blocking of Fc gammaRI (CD64), Fc gammaRII (CD32), and Fc gammaRIII (CD16) individually or together also reduced neutrophil uptake of AdLuc, although less than blocking of CD35 alone. Combined CR1 and Fc receptor blockade synergistically inhibited neutrophil-AdLuc interactions close to baseline. These results demonstrate opsonin-dependent adenovirus vector interactions with neutrophils and their corresponding receptors.

Autoantibodies to the high-affinity IgE receptor in chronic urticaria: how important are they?

PURPOSE OF REVIEW

Eighty to 90% of patients with chronic urticaria have no specific external cause for their disease, which is therefore labeled 'chronic idiopathic urticaria'. We now know, however, that as many as 30-50% of patients have evidence of an autoantibody to the high-affinity receptor for IgE (FcepsilonRI), which may be pathogenic. The exact prevalence and role of these autoantibodies is still under investigation.

RECENT FINDINGS

The frequency of autoantibodies to FcepsilonRI in chronic urticaria has been estimated at 30-50%, but extensive epidemiological studies have not been done. Recent work has confirmed that autoantibodies to FcepsilonRI can be functional, meaning that they can cause histamine release from basophils in vitro. Evidence increasingly suggests that such autoantibodies are also functional in vivo, but conclusive evidence is still lacking. Approximately 50% of cases of urticaria still have no known cause, but recent studies have demonstrated that some of these patients may have intrinsic abnormalities of basophils or mast cells.

SUMMARY

The recent evidence that is discussed in this review helps to clarify the role of autoantibodies in some cases of urticaria, but also points towards other non-autoimmune mechanisms that might be pathogenic. Further investigation in these areas will help us to understand the cause of urticaria in cases that are still classified as 'idiopathic'.

Validation of basophil histamine release against the autologous serum skin test and outcome of serum-induced basophil histamine release studies in a large population of chronic urticaria patients

BACKGROUND

Endogenous histamine-releasing factors (HRFs) are involved in 30-60% of patients with chronic urticaria (CU). Evidence for their existence comes from in vivo studies of autoreactivity with the autologous serum skin test (ASST), in vitro immunoassays demonstrating autoantibodies against the immunoglobulin E (IgE) or the high affinity IgE receptor (FcepsilonRI) and serum-induced histamine release (HR) from basophils and mast cells. We have examined the correlation between the ASST and a new basophil histamine-releasing assay (the HR-Urtikaria test) in a group of well-characterized CU patients and subsequently determined the frequency of HR-Urticaria-positive sera from a larger population of CU patients.

SUBJECTS

Group 1 consisted of 28 patients with CU (16 were ASST-positive) 20 patients with atopic dermatitis, 24 patients with allergy to birch and nine healthy controls. Group 2 consisted of 873 unselected CU patients.

METHODS

White blood cells containing 1-2% basophils from a healthy nonatopic donor were incubated with patients sera in the presence of interleukin (IL)-3. Histamine was measured by the glass fibre method.

RESULTS

Using the ASST as the true outcome, the HR-Urticaria test showed a sensitivity and specificity of 75% in group 1 using a cut-off value for HR of >16.5%. None of the controls was positive in the HR-Urticaria test. In group 2, we found no difference in the frequency of positives between male (34.6%, n = 254) and female adults (35.1%, n = 576) but twice as many females as males were tested.

CONCLUSIONS

Our studies have shown that the HR-Urticaria test has a good sensitivity and specificity for endogenous HRFs demonstrated by the ASST in patients with CU and that about one-third of unselected patients with CU have a positive result.

No evidence of increased serum substance P levels in chronic urticaria patients with and without demonstrable circulating vasoactive factors

The neuropeptide substance P is a possible candidate as histamine-releasing factor in some patients with chronic ordinary urticaria (COU), particularly in those with evidence of a nonautoantibody circulating histamine-releasing factor. In this study, serum substance P levels were measured by enzyme immunoassay in 117 COU patients, 40 atopic subjects and 24 normal subjects. In vivo and in vitro assays for histamine-releasing factors, autologous serum skin test (ASST) and basophil histamine release (BHR) assay, respectively, were performed in all COU patients. Mean serum substance P concentration was not significantly different in COU patients and in normal subjects; however, significantly higher levels were detected in atopic subjects than in COU patients (P < 0.003). ASST and BHR assays allowed us to distinguish different subsets of COU patients. Mean serum substance P concentration did not vary significantly in the different subsets of patients. Nevertheless, interestingly three patients with positive ASST and negative BHR assay showed very high substance P levels. These results suggest that substance P does not play an important role as histamine-releasing factor in COU in general but only in occasional patients in whom it might act as a trigger of urticarial symptoms.

The autologous serum skin test in the follow-up of patients with chronic urticaria

BACKGROUND

The presence of anti-FcepsilonRI and anti-IgE autoantibodies in a subset of patients with chronic urticaria suggests their aetiopathogenetic role. In clinical practice, the presence of these antibodies is usually considered when the autologous serum skin test (ASST) is positive.

AIMS

To evaluate if the positive ASST follows up the activity of chronic urticaria.

METHODS

Autologous serum skin test and thyroid autoantibody detection were performed in 82 patients with chronic urticaria and repeated 1 year later, when the vast majority of patients were symptom-free. Twenty patients with Hashimoto thyroiditis (HT), who had never suffered from urticaria, represented the control group.

RESULTS

At the start of the study, the prevalence of positive ASST was 46.6%. The association of HT-urticaria was 29.3%. ASST was positive in 62 and 39% of patients with and without HT, respectively (P > 0.05 ns). One year later, 28 of 34 patients with a positive ASST were symptom-free, but 50% of them were positive for ASST. The ASST was positive in 86.7 and 8% of patients with and without HT, respectively (P < 0.001). In the control group, ASST was always negative.

CONCLUSIONS

The co-existence of autoimmune thyroiditis with chronic urticaria seems to induce a significant difference in the persistence of a positive ASST. Consistent with previous reports, a positive ASST correlates with disease exacerbation in chronic urticaria patients without thyroiditis. In patients with thyroiditis and urticaria, positive ASST persists even after the urticaria has disappeared, thus questioning whether a positive ASST to be a surrogate marker of the functional role of anti-FcepsilonRI and anti-IgE autoantibodies.

Autoimmune urticaria

A growing body of evidence shows that at least 40% of patients with unexplained (idiopathic) chronic urticaria have clinically relevant functional autoantibodies to the high-affinity IgE receptor on basophils and mast cells. The term "autoimmune urticaria" is used for this subgroup of patients presenting with continuous ordinary urticaria. This article reviews the evidence for the autoimmune hypothesis and other nonantibody serum histamine-releasing factors in the etiopathogenesis of urticaria; defines autoimmune urticaria; looks at how autoimmune urticaria fits into existing classifications of urticaria; proposes diagnostic criteria that may be useful to the clinician; and reviews the management implications for patients with this subset of chronic disease.

Multiple NSAID intolerance in chronic idiopathic urticaria is correlated with delayed, pronounced and prolonged autoreactivity

Autologous serum skin test (ASST) reactivity is positive in up to 60% of patients with chronic idiopathic urticaria (CIU). About 21 to 30% of patients with CIU have intolerance to acetyl salicylic acid (ASA) and/or other chemically unrelated non-steroidal anti-inflammatory drugs (NSAIDs). To investigate the relationship between ASA/NSAID intolerance and ASST reactivity, a case-control study was performed in 110 patients with CIU and 60 healthy controls. A positive ASST was defined as an erythematous wheal with a diameter of > 5 mm more than the saline-induced response. Patients were assessed at 10-minute intervals for a minimum of three hours. ASA/NSAID intolerance was ascertained by a placebo controlled-provocation test with offending drug (s). Forty-two patients with CIU (38.2%) had autoreactivity whereas only two of the controls (3.3%) displayed early and weak skin responses (P<.0001). ASA/NSAID intolerance was demonstrated in 30 (27.3%) patients with CIU. The prevalences of autoreactivity were 93.3% (28/30) and 17.5% (14/80) in patients with and without ASA/NSAID intolerance, respectively (P<.001). Thirteen of the 25 ASST-positive patients (52%) who had single (n: 7) or multiple (n: 6) NSAID intolerance showed early (before or at 30 min) and mild autoreactivity of short duration, whereas 15 of the remaining 17 ASST-positive patients (88.2%) who all had multiple NSAID intolerance showed delayed (later than 30 min) and prolonged autoreactivity (P<.05). These findings suggest that a common mechanism may be responsible for the pathogeneses of both delayed autoreactivity and multiple NSAID intolerance in CIU. It might be further speculated that delayed, prolonged, and pronounced autoreactivity may be a possible predictor for multiple NSAID sensitivity in CIU.

Assessment of histamine-releasing activity of sera from patients with chronic urticaria showing positive autologous skin test on human basophils and mast cells

BACKGROUND

All previous studies agree that only a proportion of sera from patients with chronic urticaria (CU) positive on the autologous serum skin test (ASST) are able to induce histamine release in vitro. A non-specific release of bradykinins during clotting of blood samples has been suggested; however, ASST seems rather specific and some data point to the existence of a mast cell-specific histamine-releasing factor.

OBJECTIVE

To assess whether, and to what extent, the use of both human basophils and mast cells increases the sensitivity of in vitro histamine release assays (HRAs) in ASST-positive patients with CU.

METHODS

The histamine-releasing activity of sera from 93 patients with CU selected on the basis of strong skin reactivity on ASST was assessed in vitro on basophils from 1 (n=86), 2 (n=31), or 3 (n=20) normal donors, and on mast cells from 1 (n=3), 2 (n=3), or 3 (n=87) normal donors.

RESULTS

Sera from 88/93 (95%) patients induced significant histamine release from mast cells or basophils on at least one HRA. 76/93 (82%), 45/90 (50%), 22/80 (28%), and 6/12 (50%) sera were able to induce significant histamine release from cells of 2/5, 3/5, 4/5 and 5/5 donors, respectively.

CONCLUSION

Sera from nearly all ASST-positive patients with CU are able to induce histamine release in vitro. However, the serum from each single patient seems to show its maximal activity on autologous mast cells in vivo, and functional in vitro tests show much variability and seem less sensitive than ASST in the detection of patients with histamine-releasing factors in their blood.