Characteristics of histamine-releasing activity in the sera of patients with chronic idiopathic urticaria

Fenebrutinib in H1 antihistamine-refractory chronic spontaneous urticaria: a randomized phase 2 trial

Bruton's tyrosine kinase (BTK) is crucial for FcεRI-mediated mast cell activation and essential for autoantibody production by B cells in chronic spontaneous urticaria (CSU). Fenebrutinib, an orally administered, potent, highly selective, reversible BTK inhibitor, may be effective in CSU. This double-blind, placebo-controlled, phase 2 trial (EudraCT ID 2016-004624-35 ) randomized 93 adults with antihistamine-refractory CSU to 50 mg daily, 150 mg daily and 200 mg twice daily of fenebrutinib or placebo for 8 weeks. The primary end point was change from baseline in urticaria activity score over 7 d (UAS7) at week 8. Secondary end points were the change from baseline in UAS7 at week 4 and the proportion of patients well-controlled (UAS7 ≤ 6) at week 8. Fenebrutinib efficacy in patients with type IIb autoimmunity and effects on IgG-anti-FcεRI were exploratory end points. Safety was also evaluated. The primary end point was met, with dose-dependent improvements in UAS7 at week 8 occurring at 200 mg twice daily and 150 mg daily, but not at 50 mg daily of fenebrutinib versus placebo. Asymptomatic, reversible grade 2 and 3 liver transaminase elevations occurred in the fenebrutinib 150 mg daily and 200 mg twice daily groups (2 patients each). Fenebrutinib diminished disease activity in patients with antihistamine-refractory CSU, including more patients with refractory type IIb autoimmunity. These results support the potential use of BTK inhibition in antihistamine-refractory CSU.

Presence of positive skin prick tests to inhalant allergens and markers of T2 inflammation in subjects with chronic spontaneous urticaria (CSU): a systematic literature review

BACKGROUND

Current guidelines do not recommend performing aeroallergen skin prick testing (SPT) in chronic spontaneous urticaria (CSU).

OBJECTIVE

The objective of this review was to investigate the presence of aeroallergen sensitization and markers of T2 inflammation in subjects with CSU.

METHODS

Systematic literature reviews to identify all studies that evaluated the presence of T2 markers of allergic inflammation in CSU subjects were performed.

RESULTS

In 16 studies that assessed the prevalence of positive SPT to multiple aeroallergens in CSU, 38.5% of CSU subjects had positive SPT. In three controlled studies, 34.2% of CSU subjects had positive SPT to multiple aeroallergens, compared to 13.6% of controls (p = 0.047). In 18 studies that assessed the prevalence of house dust mite (HDM) positive SPT in CSU, 27.5% of CSU subjects had positive SPT. In three controlled studies, 27.5% of CSU subjects had positive SPT to HDM, compared to 2.1% of controls (p = 0.047). Overall, CSU subjects were 3.1 times more likely to be aeroallergen-sensitized (95% CI 1.7-5.8, p = 0.0002) and 6.1 times more likely to be HDM-sensitized (95% CI 3.7-9.9, p < 0.00001) than controls. Mean total serum IgE (tIgE) levels were 238 kU/L and median tIgE levels were 164 kU/L, which was greater than the upper 90th percentile of normal (< 137 kU/L). Compared to healthy controls, CSU subjects were 6.5 times more likely to have IgG autoantibody against FcεR1α (p = 0.001), 2.4 times more likely to have IgG anti-IgE antibody (p = 0.03) and 5 times more likely to have anti-thyroid peroxidase (anti-TPO) antibody (p = 0.02). When corticosteroids were withheld for ≥ 28 days, mean blood eosinophil percentage was elevated at 5.9% (normal < 4%), but other studies reporting absolute count found the mean was in the normal range, 239 × 10 6 / L (normal < 400 × 10 6 / L).

CONCLUSION

Increased aeroallergen sensitization, tIgE, autoantibodies and blood eosinophil percentage in the CSU subjects indicates the possible importance of T2 inflammation in the pathogenesis of CSU. Further studies may be warranted to determine if specific allergen avoidance, desensitization or improvement in the mucosal allergic inflammation present in asthma and/or rhinitis has any benefit in the management of CSU.

Complement Activation in Inflammatory Skin Diseases

The complement system is a fundamental part of the innate immune system, playing a crucial role in host defense against various pathogens, such as bacteria, viruses, and fungi. Activation of complement results in production of several molecules mediating chemotaxis, opsonization, and mast cell degranulation, which can contribute to the elimination of pathogenic organisms and inflammation. Furthermore, the complement system also has regulating properties in inflammatory and immune responses. Complement activity in diseases is rather complex and may involve both aberrant expression of complement and genetic deficiencies of complement components or regulators. The skin represents an active immune organ with complex interactions between cellular components and various mediators. Complement involvement has been associated with several skin diseases, such as psoriasis, lupus erythematosus, cutaneous vasculitis, urticaria, and bullous dermatoses. Several triggers including auto-antibodies and micro-organisms can activate complement, while on the other hand complement deficiencies can contribute to impaired immune complex clearance, leading to disease. This review provides an overview of the role of complement in inflammatory skin diseases and discusses complement factors as potential new targets for therapeutic intervention.

Comparative Study of Positive Versus Negative Autologous Serum Skin Test in Chronic Spontaneous Urticaria and its Treatment Outcome

Background:

Chronic urticaria (CU) is defined as urticaria persisting daily or almost daily for more than 6 weeks and affecting 0.1% of the population. Mast cell degranulation and histamine release are of central importance in the pathogenesis of CU. About 40-50% of the patients with chronic idiopathic urticaria (CIU) or chronic spontaneous urticaria (CSU) demonstrates an immediate wheal and flare response to intradermal injected autologous serum. This led to the concept of autoimmune urticaria (AIU).

Aims:

To determine the occurrence, clinical features, associated clinical conditions, comorbidities of AIU, and to compare this with CSU. This study aimed to find the frequency of autologous serum skin test (ASST)-positive patients among patients with CSU and to identify the clinical and laboratory parameters associated with positive ASST and to compare the treatment outcome.

Materials and Methods:

A prospective correlation study in 110 patients with CSU was conducted, after screening 200 CU patients attending the outpatient Department of Dermatology during from January 2012 to May 2013. Patients were subjected to ASST, complete blood counts, urine routine examination, liver function tests, renal function tests, thyroid function tests (T3, T4, and TSH), and urine analysis.

Results:

Out of 200 CU patients screened, 90 patients had excludable causes based on detailed history and skin prick test, and the remaining 110 patients were considered to have CSU. These 110 patients were further subjected to ASST, serum immunoglobulin E (IgE), and peripheral blood eosinophilia. ASST was positive in 48 patients and negative in 62 patients. Frequency of urticarial attacks and associated diseases such as abnormal thyroid function tests in both ASST-positive and ASST-negative patients did not show any statistical significance. Only attacks of angioedema in ASST-positive individuals were higher and were statistically significant. In the ASST-positive group, 31 (81.25%) patients showed improvement with first-line antihistamines, along with oral prednisolone and injection Histaglobulin and 10 (10.41%) patients did not show any improvement. Thirty-three (43.54%) patients in the ASST-negative group showed improvement while 13 (30.62%) patients did not show improvement.

Conclusion:

ASST is considered a screening test for AIU, which decreases the rate of diagnosis of idiopathic form of CU. ASST-positive patients in addition to antihistamines, were treated with short course of oral steroids and weekly Histaglobulin injections for 5 weeks followed by the 3^rd and 6^th months.

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.

Chronic idiopathic urticaria and Graves' disease

Chronic urticaria is a common condition characterized by recurrent episodes of mast cell-driven wheal and flare-type skin reactions lasting for more than 6 weeks. In about 75% of cases, the underlying causes remain unknown, and the term chronic idiopathic urticaria (CIU) is used to emphasize that wheals develop independently of identified external stimuli. Although CIU affects about 1.0% of the general population, its etiopathogenesis is not yet well understood. It is now widely accepted that in many cases CIU should be regarded as an autoimmune disorder caused by circulating and functionally active IgG autoantibodies specific for the IgE receptor (FceRI) present on mast cells and basophils or for IgE itself. The well-known association of CIU with other autoimmune processes/diseases represents further indirect evidence of its autoimmune origin. Autoimmune thyroid diseases, especially autoimmune thyroiditis, represent the most frequently investigated diseases in association with CIU. Here we review this topic with particular regard to the association between Graves' disease and CIU. The possible pathogenetic mechanisms and the clinical implications of such an association are discussed.

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.

Chronic urticaria: the autoimmune paradigm

Chronic urticaria is a disease consisting of spontaneous pruritic welts, present on all or most days for more than 6 weeks. It is commonly supposed to be allergic in origin, although allergy is not the cause in the majority of cases, and it has therefore been termed 'chronic idiopathic urticaria'. Recent evidence indicates that at least a subset of patients in whom no extrinsic or internal cause can be identified are in fact autoimmune in origin. This is based mainly on the detection of pathogenic autoantibodies to the high-affinity immunoglobulin E receptor FcepsilonR1, which are thought to activate cutaneous mast cells. In this article, we review the evidence that has given rise to this autoimmune 'paradigm' and its impact on diagnosis and management.

Impact of Desloratadine on Symptoms and Quality of Life in Subjects with Chronic Idiopathic Urticaria: A Multicenter, Practice-based Study

Background

Controlled trials have demonstrated the efficacy of antihistamines in the treatment of chronic idiopathic urticaria. Second-generation antihistamines are recommended as first-line therapy for chronic idiopathic urticaria. The purpose of this study was to determine the effect of desloratadine, a newer, nonsedating, second-generation antihistamine, on symptoms of chronic idiopathic urticaria, disease severity, and quality of life (QoL).

Methods

In an open-label, observational, multicenter study, 348 subjects with chronic idiopathic urticaria were given 5 mg of desloratadine once daily for 2 weeks. Outcome measures included change from baseline at Day 14 using the Aerius Quality of Life Questionnaire (AEQLQ); change from baseline in pruritus score, number and maximum size of hives, sleep quality, and activity impairment; and subjects' response to therapy.

Results

Desloratadine significantly decreased subjects' overall condition and symptom scores from baseline to Day 14 (2.19 ± [SD] 0.66 and 1.14 ± 0.89, respectively; P < 0.0001). Desloratadine treatment significantly improved all 10 AEQLQ domain scores from baseline to Day 7 and Day 14 (P < 0.0001). Sleep disturbance scores decreased 40% from baseline to Day 7 (1.42 ± 1.03 to 0.85 ± 0.89, respectively), and interference with daily outdoor activity scores showed a 41% decrease from baseline to Day 7 (1.11 ± 0.98 to 0.66 ± 0.90) (P < 0.0001 for both). There were significant reductions in itching, size of hives, and hive score at both Days 7 and 14. Treatment resulted in moderate, marked, or complete relief of symptoms in 76.2% of subjects. Desloratadine was well tolerated, with no adverse events reported.

Conclusion

In an open-label, observational study, desloratadine 5 mg once daily significantly decreased symptoms of chronic idiopathic urticaria and improved subject QoL.

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.

Basophil phenotypes in chronic idiopathic urticaria in relation to disease activity and autoantibodies

Potentially pathogenic IgG autoantibodies to IgE or its receptor, Fc epsilonRIalpha, have been detected in approximately 40% of chronic idiopathic urticaria (CIU) patients. CIU patients' basophils display distinct altered Fc epsilonRIalpha-mediated degranulation. CIU patients with basophil histamine release in response to polyclonal goat anti-human IgE > or = 10% are classified as CIU responders (CIU-R) and < 10% are CIU non-responders (CIU-NR). We compared the presence of autoantibodies to basophil degranulation phenotypes and to disease status (active or inactive). Sera were collected from non-CIU subjects and CIU subjects who participated in a longitudinal study of disease severity and had defined basophil degranulation phenotypes. Immunoenzymetric assays (IEMA) quantified IgG anti-Fc epsilonRIalpha and anti-IgE. IgG anti-Fc epsilonRIalpha antibody was detected in 57% of CIU-R (n=35), 55% of CIU-NR (n=29), and 57% of non-CIU subjects (n=23), whereas IgG anti-IgE was present in 43% of CIU-R, 45% of CIU-NR, and 30% of non-CIU subjects. Both the autoantibody levels and the functional basophil phenotype remained stable in subjects with active disease (n=16), whereas there was an enhancement in basophil function as subjects evolved into a state of remission (n=6), which appears independent of the presence of autoantibody. IEMAs detected a similar frequency of autoantibodies in CIU-R, CIU-NR, and non-CIU subjects. Basophil function may be independent of IEMA-detected autoantibodies.

Other Allergic Skin Disorders

In this chapter we discuss allergic skin disorders other than atopic dermatitis (AD): the urticaria-angioedema syndrome, allergic contact dermatitis (ACD), protein contact dermatitis (PCD), phytodermatitis, allergic photodermatitis and allergic vasculitis.

Chronic urticaria: recent advances

Chronic urticaria is an umbrella term, which encompasses physical urticarias, chronic "idiopathic" urticaria and urticarial vasculitis. It is important to recognize patients with physical urticarias as the investigation and treatment differs in important ways from patients with idiopathic chronic urticaria or urticarial vasculitis. Although relatively uncommon, urticarial vasculitis is an important diagnosis to make and requires histological confirmation by biopsy. Underlying systemic disease and systemic involvement, especially of the kidneys, should be sought. It is now recognized that chronic "idiopathic" urticaria includes a subset with an autoimmune basis caused by circulating autoantibodies against the high affinity IgE receptor (FceR1) and less commonly against IgE. Although the autologous serum skin test has been proven useful in prompting search for and characterization of circulating wheal-producing factors in chronic urticaria, its specificity as a screening test for presence of functional anti-FceR1 is low, and confirmation by demonstration of histamine-releasing activity in the patient's serum must be the benchmark test in establishing this diagnosis. Improved screening tests are being sought; for example, ability of the chronic urticaria patient's serum to evoke expression of CD 203c on donor human basophils is showing some promise. The strong association between autoimmune thyroid disease and autoimmune urticaria is also an area of ongoing research. Drug treatment continues to be centered on the H1 antihistamines, and the newer second-generation compounds appear to be safe and effective even in off-label dosage. Use of systemic steroids should be confined to special circumstances such as tapering regimens for acute flare-ups. Use of leukotriene antagonists is becoming popular, but the evidence for efficacy is conflicting. Cyclosporin is also effective and can be used in selected cases of autoimmune urticaria, and it is also effective in non-autoimmune cases, although less so.

Efficacy and safety of desloratadine in adults with chronic idiopathic urticaria: a randomized, double-blind, placebo-controlled, multicenter trial

BACKGROUND AND OBJECTIVE

Chronic idiopathic urticaria (CIU), a condition characterized by pruritus and wheals, can cause patients physical and psychological distress. Desloratadine, a second-generation histamine H(1) receptor antagonist (antihistamine), is a first-line treatment option for CIU. The objective of this study was to evaluate the efficacy and safety of once-daily desloratadine 5mg versus placebo for the treatment of CIU symptoms and disease severity in adults.

METHODS

This was a randomized, placebo-controlled, multicenter trial of 137 adult patients with active CIU who received oral once-daily desloratadine 5mg or placebo for 6 weeks. Outcome measures included pruritus severity, number of wheals, and the size of the largest wheal. Patients assessed signs and symptoms on a four-point scale twice daily. The overall therapeutic response at the end of the 6-week treatment period was also rated.

RESULTS

Desloratadine treatment was associated with significant improvements compared with placebo in pruritus scores and in the size of the largest wheals as early as day 1. These improvements continued through to the end of the trial. The mean score for the number of wheals was significantly lower in the desloratadine group than in the placebo group on days 14 and 42 (p < or = 0.016). Overall improvement in CIU (complete, marked, or moderate therapeutic response) was also greater at the end of the study in the desloratadine group compared with placebo (p < 0.001). Adverse events occurred with similar frequency among desloratadine- and placebo-treated patients.

CONCLUSION

Once-daily desloratadine 5mg is well tolerated and superior to placebo in reducing pruritus and wheals associated with CIU. Desloratadine provided rapid and sustained relief of CIU symptoms as early as after the first dose and maintained this effect until the end of the 6-week treatment period.

Autoimmunity and complement in the pathogenesis of chronic urticaria

Chronic urticaria is a debilitating skin disease that is believed to have an underlying autoimmune etiology in 35% to 50% of cases. Patients with autoimmune urticaria have functional antibodies in their sera that release histamine from basophils and mast cells. The C5a component of complement is required for mast cell degranulation in this process and at least augments basophil histamine release. In this article, the evidence that is key to our understanding of autoimmunity and complement in the pathogenesis of a subset of patients with chronic urticaria is outlined. Some of the issues in testing for and treating autoimmune urticaria are discussed.

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.

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'.

Increased plasma levels of matrix metalloproteinase-9 are associated with the severity of chronic urticaria

BACKGROUND

Matrix metalloproteinase (MMP)-9 is produced by many inflammatory cells such as macrophages, neutrophils, mast cells, eosinophils and T lymphocytes. Activated T cells are capable, through cell-cell contact, of inducing MMP-9 expression in human mast cells.

OBJECTIVE

To investigate the activation status of peripheral CD4+ T cells and the level of MMP-9 in the plasma of patients with chronic urticaria (CU), and whether MMP-9 levels are in association with CU severity.

METHODS

Study subjects included 29 patients with CU and 30 healthy control subjects. At the time of assessment, patients were divided into subgroups according to urticarial severity. Plasma levels of total MMP-9 (free pro-MMP-9 and free MMP-9) were determined by ELISA. CD4+ lymphocytes were positively selected with magnetic microbeads. After 48 h of activation, CD4+ T cells were assayed for both nuclear factor-kappa B (NF-kappa B) expression and proliferation.

RESULTS

Plasma levels of MMP-9 were found to be significantly higher in 29 CU patients compared with 18 healthy controls (186 +/- 174 vs. 31 +/- 21 ng/mL, P<0.0001). We also found a significant correlation between MMP-9 levels and urticarial severity (r = 0.92, P<0.001). In addition, CD4+ T cells from CU patients expressed higher levels of NF-kappa B than CD4+ T cells from healthy controls (82 +/- 30 vs. 69 +/- 20 optical density, P = 0.007). Finally, as compared with seven healthy individuals, DNA synthesis in CD4+ T cells from seven CU patients was found to be significantly elevated (1000 +/- 240 vs. 751 +/- 166 counts per minute, P = 0.01).

CONCLUSION

Increased levels of MMP-9 are found in CU patients, and particularly among those with severe disease. We also demonstrated that CD4+ T cells from such patients are highly activated.

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.

Functional assessment of pathogenic IgG subclasses in chronic autoimmune urticaria

BACKGROUND

Chronic urticaria is caused by a complement fixing, IgG antibody directed to the alpha-subunit of the IgE receptor, which is present in 35% to 45% of patients. This autoimmune subgroup can be identified by an autologous skin test or histamine release from human basophils or cutaneous mast cells. However, binding assays do not correlate with these functional assays. We considered the possibility that pathogenic antibody may be present within particular IgG subclasses, which might facilitate development of a binding method that can reliably screen patients.

OBJECTIVE

To determine the subclass distribution of IgG antireceptor antibodies on the basis of histamine release, and to assess the possibility that a subclass specific ELISA binding method could be used to screen patients.

METHODS

We isolated patient IgG by protein G affinity chromatography and then isolated patient IgG subclasses 1, 2, 3, and 4 by a combination of antibody affinity chromatography and protein A affinity chromatography. The ability of each subclass to activate basophils was assayed by histamine release.

RESULTS

Patient IgG subclasses IgG 1 , IgG 3 , and to a lesser degree IgG 4 have antibody capable of activating basophils to release histamine, whereas IgG 2 is inactive. Immunoblot or RAST assay that is subclass-specific does not correlate with histamine release as a result of nonfunctional but binding antibody within IgG subclasses 1, 3, or 4, and complement activation by IgG 1 and IgG 3 .

CONCLUSION

Purification of IgG subclasses from patients with chronic urticaria demonstrates functional antibody in IgG 1 and IgG 3 and occasionally IgG 4 . Nonfunctional antibody within IgG 2 plus nonfunctional antibody mixed with functional antibody within IgG 1 , IgG 3 , and IgG 4 and effects of complement are responsible for a lack of correlation of histamine release with binding assays even if subclass-specific.

Skin Prick Tests in Patients with Chronic Urticaria

Acute or chronic urticaria is not a common manifestation of systemic disease. However it affects 15% of the population at least once during their lives. The most common causes of urticaria are allergic. In all, we studied 130 patients (mean age 54.8) with chronic urticaria, 88 women and 42 men, in an effort to identify common causes of urticaria, using environmental and food allergens. 90 of our patients (69.2%) did not present with skin sensitivity. The remaining 40 individuals presented with skin sensitivity: 20 (15.3%) to food allergens, 14 (10.7%) to environmental allergens and 6 patients (4.6%) to both allergens (environmental and food). We note that in chronic urticaria it is unusual to find underlying causes.

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.

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.

Circulating stem cell factor in patients with chronic idiopathic urticaria

BACKGROUND

The nature of histamine-releasing factors involved in the pathogenesis of chronic idiopathic urticaria (CIU) is still controversial, since functional IgG autoantibodies specific for the high-affinity IgE receptor, Fc(epsilon)RI, can be detected in only 20% of patients showing a strong skin reactivity on the autologous serum skin test. The absence of systemic eosinophilia in CIU patients, along with the increase in mast cells in skin biopsy specimens, suggests a possible role for stem cell factor (SCF), the only cytokine/growth factor known to induce mediator release from human mast cells.

OBJECTIVE

To investigate the possible role of SCF as a histamine-releasing factor in patients with CIU.

METHODS

The SCF levels were measured in serum samples from 65 patients with CIU who scored strongly positive on the autologous serum skin test; of these patients, 32 had negative results and 33 had positive results on in vitro histamine release assay by a quantitative commercial sandwich immunoassay technique. Serum samples from 40 healthy subjects were used as controls.

RESULTS

Serum SCF levels in all 65 CIU patients did not differ from those found in healthy controls. No difference in SCF levels was found between patients with positive and negative results on histamine release assay.

CONCLUSIONS

An increase in serum SCF levels does not play a pathogenic role in CIU.

Intolerance to nonsteroidal anti-inflammatory drugs might precede by years the onset of chronic urticaria

BACKGROUND

Recent studies have found that most otherwise normal subjects with a history of acute urticaria induced by several nonsteroidal anti-inflammatory drugs (NSAIDs) show a wheal-and-flare reaction on intradermal injection of autologous serum. This phenomenon has been previously observed in patients with chronic urticaria (CU) and suggests a possible common background in CU and NSAID-induced urticaria. A relationship between these 2 conditions is further suggested by the fact that up to 30% of patients with CU have a worsening of their skin disorders after the ingestion of chemically unrelated NSAIDs.

OBJECTIVE

I sought to assess whether otherwise normal subjects with multiple or single NSAID intolerance show a propensity to have CU.

METHODS

Two hundred eighty otherwise normal patients with an unequivocal history of acute urticaria induced by NSAIDs seen during the last 10 years were studied. On the basis of both clinical history and oral challenge tests with at least 2 alternative NSAIDs, the patients were classified as having single or multiple NSAID intolerance. All the patients were re-evaluated within the end of 2002, 1 to 10 years after the first visit, to assess the onset of CU. One hundred allergic adults without a history of CU and of drug allergy followed up for 1 to 10 years were used as control subjects.

RESULTS

One hundred fifty-nine and 121 patients were finally considered as having single or multiple NSAID intolerance, respectively. At the follow-up visit, 93 (33%) of 280 patients had CU. The prevalence of CU was very similar in subjects with single or multiple NSAID intolerance (48/159 [30%] vs 45/121 [37%], respectively; P = not significant). Only 1 (1%) of 100 atopic control subjects had CU during the follow-up period (P <.001). Among single NSAID reactors, patients who had CU had a significantly higher prevalence of intolerance to aspirin than those who did not have CU (36/48 [75%] vs 41/111 [37%], P <.001), whereas the latter had a markedly higher prevalence of intolerance to pyrazolone drugs (52/111 [47%] vs 10/48 [21%], P <.01). Altogether, only 12 (15%) of 82 patients intolerant to drugs other than aspirin versus 36 (47%) of 77 aspirin reactors had CU (P <.001).

CONCLUSION

NSAID intolerance might precede the onset of CU by years. Both multiple and single NSAID reactors with a history of aspirin-induced urticaria seem at higher risk for CU than patients with a history of single intolerance to NSAIDs other than aspirin.

Laboratory tests and identified diagnoses in patients with physical and chronic urticaria and angioedema: A systematic review

BACKGROUND

The value of laboratory tests in chronic urticaria is still controversial.

OBJECTIVE

Our aim was to assess this value in clinical studies, and to identify factors explaining the variation in the number of identified causes.

METHODS

A total of 4 electronic databases were searched, and a manual literature search was performed. Only unselected patient series with more than 50 adult patients were included. From each included study predefined items were recorded to assess their quality (consecutive patients, use of standardized diagnostic criteria) and validity (follow-up, assessment of treatment effects, level of evidence).

RESULTS

A total of 29 studies were included, involving 6462 patients. The verification of the validity of the results and the level of evidence of the included studies were limited.

CONCLUSION

No relationship between the number of identified diagnoses and the number of performed laboratory tests, the different settings, the study design, or the publication period was found. On the basis of this systematic review and the relevant literature, a clinical guideline in the form of a flowchart is presented.

Molecular aspects of allergy

Atopic diseases such as asthma, rhinitis, eczema and food allergies have increased in most industrialised countries of the world during the last 20 years. The reasons for this increase are not known and different hypotheses have been assessed including increased exposure to sensitising allergens or decreased stimulation of the immune system during critical periods of development. In allergic diseases there is a polarisation of the Th2 response and an increase in the production of type 2 cytokines which are involved in the production of immunoglobulin E and the development of mast cells, basophils and eosinophils leading to inflammation and disease. The effector phase of atopy is initiated by interaction with Fc epsilon RI expressed on effector cells such as mast cells and basophils but also found on an ever increasing list of cells. Binding of a polyvalent allergen to the variable part of IgE leads to a cross-link of the receptor that triggers the cell to release histamine and pharmacological mediators of the symptomatic allergic response. Cross-linking of Fc epsilon RI by autoantibodies against the alpha-chain of the Fc epsilon RI, causing subsequent histamine release is thought to be involved in the pathogenesis of other diseases such as chronic idiopathic urticaria (CIU). To date, most therapeutic strategies are aimed at inhibiting and controlling components of the inflammatory response. Recently, new treatment strategies have emerged that focus on the development of preventive and even curative treatments. The most promising therapeutic approaches are aimed at inhibiting the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic anti-IgE or anti-Fc epsilon RIalpha autoantibodies. Clinical trials in humans using an humanised anti-IgE antibody showed that this antibody was well tolerated and reduced both symptoms and use of medication in asthma and allergic rhinitis. Thus interruption of the atopic cascade at the level of the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic antibodies is effective and represents an attractive therapy for the treatment of atopic disease.

Chronic idiopathic urticaria: a family study

BACKGROUND

Genetic factors play a pivotal role in the pathogenesis of many autoimmune disorders. Recent studies demonstrated that chronic idiopathic urticaria (CIU) is an autoimmune disease at least in a subset of patients, but familial studies have not yet been conducted.

OBJECTIVE

To investigate the familial pattern of CIU.

METHODS

One thousand three hundred eight adults with CIU (aged >12 years; male/female 388/920) seen during the last 10 years were thoroughly interviewed to ascertain the presence of CIU among first-degree relatives. Positive histories were confirmed by medical recordings. Proportions were compared with those expected in the general population on the basis of a 0.1% prevalence of the disease.

RESULTS

Fifty-six of 1,308 (4%) patients had a familial history of CIU affecting at least one first-degree relative. This number exceeded by approximately eight times the expected one (P < 0.001). Twenty-two of 23 (96%) patients with a positive familial history were positive on autologous serum skin test (P < 0.01 by comparison with previous studies).

CONCLUSION

The observation that CIU is much more frequent among first-degree relatives of affected individuals than in the general population suggests the existence of a genetic background for the disease and provides a clinical support to the reported association between CIU and human leukocyte antigen DR4. Ninety-six percent of patients with a positive familial history were positive on autologous serum skin test, a condition that has been associated with the presence of circulating histamine releasing factors, including anti-Fc epsilonRI or anti-immunoglobulin E antibodies.

Chronic urticaria

Chronic urticaria has a spectrum of clinical presentations and causes. About 50% of patients with "idiopathic" disease have histamine-releasing autoantibodies in their blood. The term autoimmune urticaria is increasingly being accepted for this subgroup of patients, in whom immunosuppressive therapies may be appropriate if conventional approaches to management are unsuccessful. This article reviews the classification, causes, and management of chronic urticaria in light of recent advances in the understanding of its etiology.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should have up-to-date knowledge of the classification, assessment, and management of chronic urticaria and understand where the concept of autoimmune urticaria fits into existing frameworks.

Autoreactivity is highly prevalent in patients with multiple intolerances to NSAIDs

BACKGROUND

A subset of drug-allergic patients show a marked propensity to react against several, chemically unrelated nonsteroidal anti-inflammatory drugs (NSAIDs). The pathogenesis of such multiple drug reactions is unclear. Approximately 30% of patients with chronic idiopathic urticaria, a condition frequently characterized by autoreactivity on autologous serum skin test (ASST), experience flares of hives after taking chemically unrelated NSAIDs.

OBJECTIVE

To detect whether a clinically unapparent autoreactivity may represent the nonspecific mechanism facilitating drug-induced histamine release in patients with a history of urticaria/angioedema induced by several, chemically unrelated NSAIDs.

METHODS

Thirty-six adults with a history of acute NSAID-induced urticaria (22 with multiple NSAID sensitivity [MNS]; 14 with single NSAID sensitivity [SNS]; and 20 atopic controls without a history of drug allergy) underwent ASST. Sera from 14 MNS and 4 SNS subjects (all ASST-positive) underwent histamine release assay with basophils from normal donors. Sera from five MNS patients were tested on autologous basophils as well.

RESULTS

Twenty of 22 (91%) MNS subjects versus 5 of 14 (36%) SNS subjects were positive on ASST (P < 0.01). No atopic control was ASST-positive. Sera from 4 of 14 (29%) MNS patients versus 0/4 SNS subjects (P = NS) induced significant histamine release from basophils of normal donors. The use of autologous basophils did not significantly change these results.

CONCLUSION

Most patients with multiple NSAID intolerance and approximately one-third of those with single NSAID hypersensitivity are characterized by the presence of circulating histamine-releasing factors. Their nature is still unclear, but the fact that only a minority of sera from ASST+ subjects were able to induce histamine release from normal basophils in vitro suggests that these factors might not differ from those involved in most patients with chronic urticaria. These factors might play a relevant pathogenic role in NSAID-induced urticaria reactions.

Increased expression of endothelial cell adhesion molecules due to mediator release from human foreskin mast cells stimulated by autoantibodies in chronic urticaria sera

Histamine-releasing antibodies that act against the epitope of the alpha chain of Fc(epsilon)RI (anti-Fc(epsilon)RI(alpha) antibody) that may affect pathogenesis in serum of patients with chronic urticaria. We assessed the capability of anti-Fc(epsilon)RI(alpha) antibody in sera from patients with chronic urticaria to release histamine and cytokines, and to induce the expression of endothelial cell adhesion molecules. We also assessed the release of inflammatory mediators from cultured foreskin mast cells, and expression of endothelial cell adhesion molecules on human dermal microvascular endothelial cells. Cells were pretreated with mast cell-conditioned media: culture media of mast cells treated with sera from chronic urticaria patients containing anti-Fc(epsilon)RI(alpha) antibody. Histamine release from human foreskin mast cells challenged with sera, increased after both 20 min and 16 h intervals. Leukotriene D4 release also increased at both 20 min and 16 h. Tumor necrosis factor-alpha increased significantly in foreskin mast cell culture challenged with sera of chronic urticaria patients. After the stimulation of human dermal microvascular endothelial cells with the conditioned media, the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin increased significantly. Treatment of the conditioned media with anti-tumor necrosis factor-alpha monoclonal antibody partially inhibited the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. The data suggest that sera from patients with chronic urticaria containing anti-Fc(epsilon)RI(alpha) antibody release mediators and tumor necrosis factor-alpha by activating human foreskin mast cells. This release can play a pathogenic role in chronic urticaria by activating endothelial cells, in part due to the actions of tumor necrosis factor-alpha from mast cells.

Methotrexate-responsive chronic idiopathic urticaria: a report of two cases

Chronic idiopathic urticaria (CIU) may be severe and refractory to standard therapies. We describe two patients with CIU, neither of whom had detectable autoantibodies, in whom control of the disease was achieved with methotrexate.

Chronic urticaria: novel clinical and serological aspects

BACKGROUND

Recently, distinct studies have shown that: (a) chronic idiopathic urticaria (CIU) is autoimmune in 30-50% of cases; (b) in patients with CIU the autologous serum skin test is inhibited by heparin; and (c) basophil histamine release induced in vitro by CIU sera maybe complement-dependent.

OBJECTIVE

To carry out a comprehensive clinical and serological study on CIU based upon these observations.

METHODS

Three hundred and six adults with CIU underwent intradermal (ID) test with autologous serum; 57 of them with autologous heparinized plasma as well. Sera from 121 patients (plasmas from 17) were employed to induce in vitro histamine release from basophils of normal donors. The effects of heating (56 degrees C, 60 min), filtration through membrane, and preincubation with heparin were evaluated as well.

RESULTS

Autologous serum and plasma induced a weal and flare reaction in 205 out of 306 (205/306; 67%) and in 8/57 (14%) patients, respectively. Positive plasma skin tests were observed only in patients showing strongly positive serum skin tests. Plasma did not elicit any skin reaction in 3/3 patients with dermatographism who showed a positive intradermal test with saline. Sera from 20/121 (16.5%) patients induced significant histamine release from basophils of normal donors. 19/20 sera were from patients with a positive intradermal test; thus, basophil histamine release assay was positive in 19/87 (21.8%) patients with a positive serum skin test. Heating at 56 degrees C x 1 h markedly reduced the histamine-releasing activity of both serum and plasma from in vitro reactors. Ultrafiltered fractions > 100 kDa of both sera tested retained the histamine-releasing activity, whereas fractions < 100 kDa were not able to induce any histamine release. Heparin dose-dependently inhibited histamine release induced by sera and plasma, and by basophil agonists such as anti-IgE, formyl-methionyl-leucyl-phenilalanine, and interleukin (IL)-3.

CONCLUSIONS

67% of our patients with CIU showed a positive autologous serum skin test. Sera from about 20% of those positive on autologous serum skin test induced histamine release from normal basophils in vitro probably as a consequence of the presence of functional autoantibodies. The marked difference between in vivo and in vitro findings could reflect the existence of a mast cell-specific histamine-releasing factor which does not release histamine from basophils of healthy blood donors. However, it might be also the result of in vivo priming of patients' cutaneous mast cells or of heterogeneity of basophil donors. At least in some cases complement seems essential for histamine-releasing activity of serum from patients with CIU. Heparin inhibits histamine release from both basophils (in vitro) and mast cells (in vivo), probably acting directly at a cellular level.

Mechanisms of autoimmune activation of basophils in chronic urticaria

BACKGROUND

Approximately 35% to 40% of patients with chronic urticaria possess a circulating antibody directed to the alpha subunit of the high-affinity type I IgE receptor (FcepsilonRI), which is detectable by using histamine release assays or immunoblotting. Prior reports suggest that purified IgG may not directly activate basophils but rather does so through complement activation.

OBJECTIVE

We sought to further elucidate the mechanism by which this antibody causes basophil histamine release, including the role of complement, and to reassess the relationship of functional versus binding assays.

METHODS

We incubated human basophils with patient serum, patient IgG, or patient IgG plus normal serum as a complement source and measured histamine release for each condition. IgG fractions were neutralized with cloned alpha subunit to determine whether histamine release decreased proportionately. We also screened sera from 260 patients to compare histamine release with immunoblotting results.

RESULTS

We initially tested 35 sera from patients with chronic urticaria by using basophils from 2 atopic donors and one nonreleaser with rabbit anti-IgE. No histamine was released from the nonreleaser, yet all donors responded identically to monocyte chemotactic protein 1, indicating a requirement for IgE or the IgE receptor. Basophil histamine release was markedly augmented by complement if release by IgG alone was low. Incubation of purified IgG with an increasing concentration of cloned alpha subunit gradually reduced the histamine-releasing capability in patients with positive or negative immunoblot results. Of 260 patients tested, 43% had positive histamine release results, and 47% had positive immunoblot results, yet there was no correlation when individual patients were assessed.

CONCLUSION

A subpopulation of patients with chronic urticaria possess IgG antibody directed to the alpha subunit of FcepsilonRI. This IgG activates basophils, which is dependent on or augmented by complement. Binding assays for the FcepsilonRI alpha subunit, such as immunoblotting, are not currently feasible as a screening method. A functional assay is required.

Multiple drug allergy syndrome: a distinct clinical entity

Multiple drug allergy syndrome is a clinical condition characterized by a propensity to react against different, chemically unrelated antibiotic or nonantibiotic drugs. The origin of this syndrome is still elusive. This article critically examines the medical literature on multiple drug allergy syndrome, compares and discusses recent personal observations obtained in patients with intolerance to multiple antibiotic or anti-inflammatory drugs, suggests possible pathogenic mechanisms for this type of drug allergy, and reports on current personal research in this field.

Randomized double-blind study of cyclosporin in chronic 'idiopathic' urticaria

BACKGROUND

Histamine-releasing activity (HRA) is detectable in up to 50% of patients with chronic ordinary urticaria.

OBJECTIVES

To determine the effect of cyclosporin on clinical features and HRA in patients with chronic urticaria.

METHODS

Thirty patients with severe unremitting disease, responding poorly to antihistamines and showing a positive autologous serum skin test (ASST) as a marker of HRA, were randomized to 4 mg kg-1 daily of cyclosporin (Sandimmun, n = 20) or placebo (n = 10) for 4 weeks. Non-responders were offered open-label cyclosporin for 4 weeks. All were followed for up to 20 weeks or until clinical relapse; all took cetirizine 20 mg daily throughout the study. The primary measure of efficacy was a daily urticaria activity score (UAS) of weal numbers and itch (maximum score 42 per week). A positive response was defined as a reduction to < 25% of baseline weekly UAS and relapse as a return to > 75%. The effect of cyclosporin on serum HRA was assessed by in vitro basophil histamine release assays and ASSTs before and after treatment.

RESULTS

Twenty-nine patients (19 active, 10 controls) completed the randomized trial medication. Eight of 19 on active treatment but none on placebo had responded at 4 weeks (P < 0.05). Three others on active drug met the criterion for response at 2 weeks but not at 4 weeks. Mean reduction in UAS between weeks 0 and 4 was 12.7 (95% confidence interval, CI 6.6-18.8) for active and 2.3 (95% CI - 3.3-7.9) for placebo (P = 0.005). Seventeen non-responders (seven randomized to active and 10 to placebo) chose open-label cyclosporin and 11 responded after 4 weeks. Six of the eight randomized active drug responders relapsed within 6 weeks. Of the 19 responders to randomized and open-label cyclosporin, five (26%) had not relapsed by the study end-point. Mean in vitro serum HRA fell from 36% (95% CI 22-49%) to 5% (95% CI 1-8%) after cyclosporin treatment (n = 11, P < 0.0001). The ASST response to post-treatment serum was also reduced (P < 0.05).

CONCLUSIONS

This study shows that cyclosporin is effective for chronic urticaria and provides further evidence for a role of histamine-releasing autoantibodies in the pathogenesis of this chronic 'idiopathic' disease.

Chronic urticaria

Chronic urticaria remains a major problem in terms of etiology, investigation, and management. It is important to identify patients in whom physical urticaria is the principal cause of disability. Once confirmed by appropriate challenge testing, no further investigation is required. Urticarial vasculitis (UV) is a major differential diagnosis of "idiopathic" urticaria (CIU). I perform biopsy of most patients in this category because UV cannot be considered confirmed in the absence of histologic evidence. Patients with confirmed UV need to be thoroughly investigated for paraproteins, lupus erythematosus hepatitis B and C, and inflammatory bowel disease. Of patients with CIU, a few (<5%) prove to have food additive reactivity confirmed by placebo-controlled challenge testing. There is no convincing evidence of the involvement of Helicobacter pylori or parasite infestation as a cause of chronic urticaria, although H pylori could have an indirect role. Recently it has become clear that 27% to 50% of patients with CIU have functional autoantibodies directed against the alpha-chain of the high-affinity IgE receptor or less commonly against IgG. These antibodies, whose involvement has now been independently confirmed in several centers, are identified by autologous serum skin testing and confirmed by histamine release studies or immunoblotting. Their removal (by intravenous Ig or plasmapheresis) or treatment by cyclosporine has proved highly beneficial in severely affected patients. However, the routine treatment of all CIU patients, irrespective of etiology, remains the judicious use of H(1) antihistamines.

Chronic urticaria serum induces histamine release, leukotriene production, and basophil CD63 surface expression--inhibitory effects ofanti-inflammatory drugs

BACKGROUND

A role of potential histamine-releasing autoantibodies against the high-affinity IgE receptor on the surface of basophils and mast cells is discussed in the pathogenesis of chronic urticaria. This so-called autoimmune urticaria may be diagnosed by a positive intracutaneous autologous serum skin test, which is found in about 30% of patients with chronic urticaria.

OBJECTIVE

Our purpose was, first, to compare the effect of complement-inactivated sera of 20 patients with chronic urticaria and positive autologous serum skin tests, 20 patients with chronic urticaria and negative skin tests, and 20 control subjects without chronic urticaria (10 atopic and 10 nonatopic subjects) and, second, to analyze the effect of anti-inflammatory drugs on the serum activity.

METHODS

The following assay systems were used: release of histamine in whole blood samples, surface expression of the activation marker CD63 on basophils, and sulfidoleukotriene de novo production in leukocyte suspensions. Whole blood, basophils, and leukocyte suspensions were obtained from a nonatopic and an atopic donor.

RESULTS

Sera of patients with autologous serum skin test positive chronic urticaria resulted not only in significantly increased histamine release compared with skin test-negative chronic urticaria sera but also in a significant higher induction of basophil CD63 surface expression and sulfidoleukotriene de novo production. However, serum activity was neither characteristic for chronic urticaria nor for chronic urticaria with a positive autologous serum skin test. Preincubation with dapsone, chloroquine, and lidocaine dose dependently resulted in a significant reduction of all histamine release, CD63 expression, and sulfidoleukotriene production. In addition, mizolastine was able to inhibit serum-induced sulfidoleukotriene production.

CONCLUSION

Further studies investigating the in vivo effect of these drugs will have to clarify their role in the management of the subset of patients with chronic urticaria demonstrating serum-induced inflammatory effects.

Human leucocyte antigen class II associations in chronic idiopathic urticaria

The major histocompatibility complex (MHC) acts as a marker for self during T-cell ontogeny and is associated with the pathogenesis of many autoimmune diseases. Recent investigations have shown about 30% of patients with chronic idiopathic urticaria (CIU) have IgG autoantibodies against the high-affinity IgE receptor, FcepsilonRI, or IgE. A link between MHC class II alleles and CIU has not been reported previously. DNA was extracted from blood of 100 Caucasian patients with CIU, and the MHC class II type determined using the polymerase chain reaction with sequence-specific primers, testing for DRB and DQB1 alleles. The frequency of alleles in CIU patients was compared with that found in 603 controls. Further human leucocyte antigen (HLA) typing on patient subsets, classified by the patients' responses to intradermal injection of autologous serum and their serum-induced histamine release from basophil leucocytes of healthy donors, was undertaken. HLA DRB1*04 (DR4) and its associated allele, DQB1*0302 (DQ8), are raised in CIU patients compared with a control population (P = 2 x 10-5 and P = 2 x 10-4, respectively). HLA DRB1*15 (DR15) and its associated allele, DQB1*06 (DQ6), are significantly less frequently associated with CIU. The HLA DRB1*04 association is particularly strong (corrected P = 3.6 x 10-6) for patients whose serum has in vivo and in vitro histamine-releasing activity. HLA class II typing is consistent with the concept that CIU is a heterogeneous disease, and supports an autoimmune pathogenesis in a subset of patients.