What the first 10,000 patients with chronic urticaria have taught me: A personal journey

A Comparative, Three-Arm, Randomized Clinical Trial to Evaluate the Effectiveness and Tolerability of Bilastine vs Fexofenadine vs Levocetirizine at the Standard Dose and Bilastine vs Fexofenadine at Higher Than the Standard Dose (Up-Dosing) vs Levocetirizine and Hydroxyzine (in Combination) in Patients with Chronic Spontaneous Urticaria

Introduction

Though second-generation antihistamines (SGAH) are first-line drugs in chronic spontaneous urticaria (CSU), 50% of patients do not respond to them. In such patients, guidelines recommend either up-dosing of SGAH or combination of different antihistamines. However, the studies comparing these treatment regimens are limited.

Methods

In this comparative, three-arm study, CSU patients were randomized to receive standard dose of either bilastine, fexofenadine, or levocetirizine for 2 weeks. After 2 weeks of treatment, non-responders received double dose of either bilastine or fexofenadine, while hydroxyzine 25 mg once daily was added in the levocetirizine group. Patients were primarily evaluated for improvement in CSU, quality of life, and somnolence.

Results

A total of 110 patients with CSU were recruited. At the end of 4 weeks, 33/39, 26/35, and 22/36 patients in the bilastine, fexofenadine, and levocetirizine groups showed improvement in urticaria symptoms. At week 2, there was no statistical difference in urticaria activity score (UAS7) improvement between any of the groups; however, at week 4, there was a statistical difference between the bilastine and levocetirizine groups (p<0.05). Somnolence was significantly lower in the bilastine group (p<0.05). Bilastine was statistically significant (p<0.05) in the improvement of quality of life as compared to both groups. No major adverse events were reported during study period; however, bilastine was associated with significantly lower levels of AEs compared to levocetirizine (p<0.05).

Conclusion

Two-fold up-dosing of bilastine improves CSU symptoms without compromising safety as compared to two-fold up-dosing of fexofenadine and combination of first- and second-generation antihistamines.

Chronic urticaria in children - New insights from a large cohort

BACKGROUND

Chronic spontaneous urticaria is well-described in adults, but less so in children. The aim of this study is to describe the demographics, clinical characteristics, comorbidities, and outcomes of children with chronic, spontaneous urticaria.

METHODS

This retrospective study followed children up to 18 years old, diagnosed with chronic spontaneous urticaria, between the years 2002-2018, and treated in a tertiary referral allergy and clinical immunology center. Data including demographics, clinical characteristics, comorbidities, treatments, and outcomes were extracted from electronic medical records.

RESULTS

Records of 380 children coded to have chronic urticaria were reviewed, of which 250 (65.8%) fulfilled the diagnostic criteria for chronic spontaneous urticaria. There were 136 females (54.4%). Mean age at diagnosis was 11.4 years, and 122 (48%) were adolescents. The average duration of chronic spontaneous urticaria was 12.25 ± 15.2 months. The urticaria in 208 children )83.2%) resolved within 24 months. Eighty-seven patients (34.8%) had at least one atopic disease. Atopic comorbidities included atopic dermatitis in 17.2%, allergic rhinitis in 16%, asthma in 13.2%, and food allergy in 3.2%. Eighteen patients (7.2%) had a concomitant autoimmune disease. Nine (3.6%) had thyroid disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Chronic spontaneous urticaria in children is a self-limited disease with favorable prognosis. Atopic diseases are more prevalent in children with chronic spontaneous urticaria than in the general pediatric population, increasing the possibility of a special subgroup of TH2-related chronic urticaria in children.

Canakinumab Lacks Efficacy in Treating Adult Patients with Moderate to Severe Chronic Spontaneous Urticaria in a Phase II Randomized Double-Blind Placebo-Controlled Single-Center Study

BACKGROUND

Chronic idiopathic/spontaneous urticaria (CSU) is a common disease with a significant proportion of patients who do not respond to standard therapy with antihistamines and optionally corticosteroids/immunosuppressants.

OBJECTIVE

The IL-1β antagonist canakinumab is effective in cryopyrin-associated periodic syndromes associated with urticarial symptoms and urticarial vasculitis, and so it was suspected that it could also be effective in patients with CSU.

METHODS

The effect of canakinumab was investigated in 20 patients with moderate to severe CSU in a 1:1 randomization to either canakinumab or placebo in a double-blind single-dose crossover design. The verum group received 150 mg canakinumab subcutaneously once at baseline. Patients who had received placebo were able to switch to canakinumab at week 4 if they did not improve. The primary end point was clinical improvement at week 4 compared with baseline in sum of urticaria activity scores over 7 consecutive days. Secondary end points were the clinical improvement at week 8 compared with baseline in sum of urticaria activity scores over 7 consecutive days and the clinical improvement measured by the Physician Score and Dermatology Life Quality Index at week 1, 2, 4, and 8.

RESULTS

At week 4, 2 patients with canakinumab and 3 with placebo met the primary end point, and so canakinumab failed the significant superiority to the placebo (P = 1.0). An inclusion of the patients who switched to canakinumab after 4 weeks did not alter the result. There was also no significant difference between the verum and placebo groups for all secondary end points. The therapy was well tolerated, and mild adverse events were equally distributed between verum and placebo groups.

CONCLUSIONS

Because of this clinical trial with 20 patients, it must be assumed that canakinumab has no effect on lesions of CSU. This suggests that IL-1β may not play a crucial role in pathology of patients with CSU, unlike, for example, in hereditary fevers or urticarial vasculitis, where targeting IL-1 is a main treatment option. However, the good tolerability of canakinumab could be confirmed.

Treatment of urticaria: a clinical and mechanistic approach

PURPOSE OF REVIEW

This manuscript describes the recommended therapy of chronic spontaneous urticaria based on our understanding of the pathogenesis of hive formation. Thus, the mechanism of action of each medication is elaborated in addition to a discussion of clinical utility.

RECENT FINDINGS

The main drugs are antihistamines, omalizumab, and cyclosporine with a success rate of 40-55, 65-80, and 70-80%, respectively. Used in sequence, over 90% of patients can be successfully treated. The addition of omalizumab represents a major advance because of its efficacy, easy utility, and favorable side-effect profile. The interaction with IgE eliminates any reaction with antigens to which it might be directed, down regulates IgE receptors on mast cells and basophils, and leads to down-regulation of mast cell functions with amelioration of hives.

SUMMARY

The use of antihistamines in high dosage (at least four times a day) is effective in close to half the patients with CSU. For antihistamine resistance, the use of omalizumab has revolutionized therapy of antihistamine-resistant cases because of its efficacy and excellent side-effect profile. If the response is insufficient, cyclosporine is the next choice. Patients should be monitored regarding any adverse effects on blood pressure or renal function. All these are far safer than extended use of corticosteroid.

Chronic Urticaria: An Overview of Treatment and Recent Patents

Background:

Up to 1% of the general population in the USA and Europe suffer from chronic urticaria (CU) at some point in their lifetime. CU has an adverse effect on the quality of life.

Objective:

This study aims to provide an update on the epidemiology, pathogenesis, clinical manifesta-tions, diagnosis, aggravating factors, complications, treatment and prognosis of CU.

Methods:

The search strategy included meta-analyses, randomized controlled trials, clinical trials, reviews and pertinent references. Patents were searched using the key term “chronic urticaria” at the following links: www.google.com/patents, www.uspto.gov, and www.freepatentsonline.com.

Results:

CU is a clinical diagnosis, based on the episodic appearance of characteristic urticarial lesions that wax and wane rapidly, with or without angioedema, on most days of the week, for a period of six weeks or longer. Triggers such as medications, physical stimuli, and stress can be identified in 10 to 20% of cases. C-reactive protein/erythrocyte sedimentation rate, and complete blood cell count with differential are the screening tests that may be used to rule out an underlying disorder. The mainstay of therapy is reassurance, patient education, avoidance of known triggers, and pharmacotherapy. Second-generation H1 antihistamines are the drugs of choice for initial therapy because of their safety and efficacy profile. If satisfactory improvement does not occur after 2 to 4 weeks or earlier if the symptoms are intolerable, the dose of second-generation H1 antihistamines can be increased up to fourfold the manufacturer’s recom-mended dose (all be it off license). If satisfactory improvement does not occur after 2 to 4 weeks or earlier if the symptoms are intolerable after the fourfold increase in the dosage of second-generation H1 antihis-tamines, omalizumab should be added. If satisfactory improvement does not occur after 6 months or earli-er if the symptoms are intolerable after omalizumab has been added, treatment with cyclosporine and sec-ond-generation H1 antihistamines is recommended. Short-term use of systemic corticosteroids may be considered for acute exacerbation of CU and in refractory cases. Recent patents for the management of chronic urticaria are also discussed. Complications of CU may include skin excoriations, adverse effect on quality of life, anxiety, depression, and considerable humanistic and economic impacts. On average, the duration of CU is around two to five years. Disease severity has an association with disease duration.

Conclusion:

CU is idiopathic in the majority of cases. On average, the duration of CU is around two to five years. Treatment is primarily symptomatic with second generation antihistamines being the first line. Omalizumab has been a remarkable advancement in the management of CU and improves the quality of life beyond symptom control.

Effectiveness and safety of antihistamines up to fourfold or higher in treatment of chronic spontaneous urticaria

Background

Treatment with second-generation antihistamines is recommended in patients with chronic spontaneous urticaria (CSU). Some patients remain unresponsive even after up-dosing up to fourfold. Many third line treatment options have limited availability and/or give rise to significant side effects. We investigated effectiveness and safety of antihistamine treatment with dosages up to fourfold and higher.

Methods

This retrospective analysis of patients’ records was performed in adult CSU patients suffering wheals and/or angioedema (AE). Demographic, clinical, and therapeutic data was extracted from their medical records. We recorded the type, maximum prescribed dosage, effectiveness, and reported side effects of antihistamine treatment.

Results

Of 200 screened patients, 178 were included. Treatment was commenced with a once daily dose of antihistamines. Persisting symptoms meant that up-dosing up to fourfold occurred in 138 (78%) of patients, yielding sufficient response in 41 (23%). Up-dosing antihistamines was necessary in 110 (80%) patient with weals alone or weals with angioedema and 28 (64%) with AE only (p = 0.039). Of the remaining 97 patients with insufficient response, 59 were treated with dosages higher than fourfold (median dosage 8, range 5–12). This was sufficient in 29 patients (49%). Side effects were reported in 36 patients (20%), whereof 30 (17%) experienced somnolence. Side effects after up-dosing higher than fourfold were reported in six out of 59 patients (10%).

Conclusion

Up-dosing antihistamines higher than fourfold dosage seems a feasible therapeutic option with regards to effectiveness and safety. The need for third line therapies could be decreased by 49%, with a very limited increase of reported side effects.

Autologous Serum and Plasma Skin Tests in Chronic Spontaneous Urticaria: A Reappraisal

AIM

The objective of this study was to assess autologous serum skin test (ASST) vs autologous plasma skin test (APST) response in chronic spontaneous urticaria (CSU) patients and study the significance of intensity of positive responses in relation to clinicoepidemiological parameters.

MATERIALS AND METHODS

One hundred CSU patients and 100 age and sex-matched controls were recruited. The demographic and clinical features were recorded in all patients and routine investigations were performed. ASST and APST tests were performed as per the standard guidelines.

RESULTS

The mean duration of illness was 4.85 ± 5.07 years, 90% patients were APST (+), 68% ASST (+), and 22 patients were only APST (+). Positive predictive value (PPV) of ASST and APST was 90.7% and 95.7%, respectively. A significant inverse association was seen between thyroid status and serum IgE levels with APST and ASST positivity.

CONCLUSION

APST appears to have better PPV and high intensity of positive response on autologous tests, and correlates with ANA positivity and angioedema.

Treatment of chronic urticaria in children with antihistamines and cyclosporine

BACKGROUND

Chronic idiopathic urticaria, daily hives that last >6 weeks, can be resistant to antihistamines, even when higher than conventional doses are used. Other pharmacologic agents have been associated with inconsistent benefit.

OBJECTIVE

We examined the relationship of clinical characteristics and the presence of autoimmune antibodies to antihistamine resistance in children. We further examined the efficacy and safety of cyclosporine in children whose urticaria was resistant to antihistamine.

METHODS

Patients referred to the pediatric allergy and pulmonary specialty clinic at the University of Iowa Children's Hospital and diagnosed as having chronic idiopathic urticaria were identified during the period from August 2008 to July 2013. A retrospective examination of treatment and outcome was performed.

RESULTS

Forty-six patients, 26 female patients and 20 male patients, with chronic idiopathic urticaria were identified. The ages of 16 patients who were antihistamine resistant ranged from 9 to 18 years (median, 12.5 years). Those patients who were antihistamine responsive had a median age of 6 years, significantly lower than those who were antihistamine resistant (P = .0001). There was no significant association between autoimmune antibodies and antihistamine resistance. All the patients who were antihistamine resistant were treated with cyclosporine; all experienced complete resolution of urticaria at times that ranged from 2 days to 3 months (median, 7 days). Relapses responsive to repeated cyclosporine occurred in 5 of the patients after 1 week to 15 months (median, 6 months). Adverse effects were not seen in these patients.

CONCLUSION

Our data were consistent with efficacy and safety of cyclosporine for chronic urticaria in children when even high doses of antihistamines are ineffective.

Therapy of chronic urticaria: a simple, modern approach

OBJECTIVE

To examine the available treatment choices for chronic spontaneous urticaria (CSU) and discuss a new paradigm for treating such patients.

DATA SOURCES

The literature regarding treatment is reviewed, including considerations of published guidelines. Attention is focused on the most recent evidence indicating particular efficacy of omalizumab.

RESULTS

Omalizumab has been found to have considerable efficacy in phase 2 and phase 3 trials in which more than 900 patients have been studied. A response rate of 65% is seen in patients resistant to antihistamines as well as to histamine2 blockers and leukotriene antagonists, and 40% of patients are completely free of hives as long as therapy is continued. In addition, serious adverse events have not been seen. Only cyclosporine can match this response rate (excluding steroids), but the adverse effect profile (blood pressure and renal function) is substantial by comparison. Double-blind, placebo-controlled studies of other agents often listed as alternatives are lacking (ie, whether their success rate exceeds the 25%-30% placebo response is uncertain). The mechanism by which omalizumab works in CSU is not clear because the response rate is unrelated to the autoimmune profile and can occur rapidly (ie, within a few days).

CONCLUSION

Omalizumab has exceptional efficacy for antihistamine-resistant CSU with an excellent adverse effect profile.

Challenges in the management of chronic urticaria

The term "chronic idiopathic urticaria" denotes a spectrum of conditions with different poorly understood pathogenetic mechanisms in which the release of histamine plays a role. Nonsedating second-generation H1 antihistamines are postulated to be the first line of treatment of chronic idiopathic urticaria by national and international guidelines, but as control is not always achievable with the usually recommended doses, first-generation sedating antihistamines like hydroxyzine and diphenhydramine at high daily doses (200 mg) have been proposed as an alternative before resorting to treatment with systemic corticosteroids and other potentially hazardous agents. Our long time experience and recent research give us grounds to believe that increasing the doses of nonsedating H1 antihistamines up to fourfold improves significantly the chances of successful treatment. Our data suggest that the urticaria-associated discomfort is relieved by higher than conventional doses of levocetirizine and desloratadine in about 75% of the patients and that sedation/somnolence does not seem to be a major deterrent. The dose increase also improves the urticaria-specific quality of life. Contrary to the belief that individual patients may benefit from one antihistamine or another, we demonstrate that the drug with better ability to suppress the histamine skin effects in experiments in healthy volunteers (levocetirizine) is also superior in improving the different aspects of control of chronic urticaria (subjective and objective symptoms, quality of life) and that increasing its dose of up to fourfold may even paradoxically reduce the sense of sedation/somnolence in parallel with the relief of urticaria discomfort.

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.

Treatment of chronic spontaneous urticaria

Chronic spontaneous urticaria is defined as persistent symptoms of urticaria for 6 weeks or more. It is associated with autoimmunity in approximately 45 percent of patients. Therapy is often difficult however the initial approach should employ high-dose non-sedating antihistamines; 4-6 tablets/day may be necessary. It has been shown that the response to 4 tablets/day exceeds 3, and exceeds 2, which exceeds 1. However the dose that corresponds to the maximal dose of first generation antihistamines (hydroxyzine, diphenhydramine) used previously, is 6/day. Yet over half the patients are refractory to antihistamines and other agents should be tried next. Whereas current guidelines (published) often add leukotriene antagonists and/or H₂ receptor antogonists next, these are of little utility. Likewise drugs effective for urticarial vasculitis (colchicine, dapsone, sulfasalazine, hydroxychloroquine) are effective in a small percentage of patients and no study suggests that the response rate of any of them exceeds the 30% placebo responses seen in most double-blind, placebo controlled studies. The drugs that are effective for antihistamine-resistant chronic spontaneous urticaria are corticosteroids, cyclosporine, and Omalizumab. Use of steroids is limited by toxicity. If used at all, a dose of no more than 10 mg/day should be employed with a weekly reduction of 1 mg. The response rates to cyclosporine and Omalizumab are each close to 75%. Cyclosporine can be used effectively if care is taken to monitor blood pressure, urine protein, blood urea nitrogen, and creatinine, every 6 weeks. Omalizumab has the best profile in terms of efficacy/toxicity and, once approved by federal agencies for use in chronic spontaneous urticaria, a dramatic change in the treatment paradigm, whether associated with autoimmunity or not, is predicted. A phase 3 trial is currently in place. Refractoriness to both Omalizumab and cyclosporine is expected to be less than 5 percent of patients. Other agents, can then be tried.

Cyclosporin-A efficacy in chronic idiopathic urticaria

Common drugs in the therapy of chronic idiopathic urticaria (CIU) include antihistamines alone or combined with corticosteroids, but severe unresponsive patients require alternative treatments. This retrospective study aims to evaluate clinical response and safety of low-dose and long-term oral Cyclosporin-A (CyA) in unresponsive patients. One hundred and ten CIU patients, unresponsive to a previous treatment (antihistamines plus prednisone 0.2 mg/kg/day), received additional oral CyA 1–3 mg/kg/day for 6 months. The patients were subdivided into three groups (A, B, C) according to the different CyA doses. Parameters of clinical efficacy including pruritus, and size and number of wheals were evaluated at baseline, after three and six months. All adverse events were recorded. The mean total symptom severity score decreased by 63% in Group A, 76% in Group B, and 85% in Group C after 6 months. Total disappearance of the symptoms was recorded in 43 patients (39.1%): 7 (28%) of Group A; 12 (37.5%) of Group B and 24 (45%) of Group C. After a mean of 2 months from CyA suspension, 14 patients (11%) had recurrence of symptoms. Minor side effects were noted in 8 patients (7%). Our study indicates that low-dose, long-term CyA therapy is efficacious and safe in severe unresponsive CIU.

Chronic spontaneous urticaria in children: itching for insight

While there is increasing information about the pathogenesis and treatment of chronic spontaneous urticaria (csU) in adults, there is little published information about csU in children. Consequently, most of the recommendations contained in current guidelines for the prevention and treatment of csU in infants and children is based on extrapolation of data obtained in adults. To rectify this, this review points out critical gaps in our knowledge and suggests strategies which may help us to improve our understanding of this condition. How common is csU in children? What do we know about its clinical presentation and the presence of useful biomarkers? What are its common underlying causes? What is the course of csU in children? How does csU affect the everyday life of children? What treatment options are available for children? To answer these questions, two separate types of information are required. The first is information about the prevalence of the condition in the community at large and how csU affects the everyday life of both the child-patient and the parent or carer. Because most csU cases in infants and children do not come to specialists but are treated by general practitioners or by parents using over-the-counter medications, these questions may be answered only by general population surveys or schools programmes. The second is clinical information including family history and disease presentation, the presence of biomarkers and comorbidities, objective measures of severity, frequency and duration of exacerbations, the response to therapy and the time to remission. Targeted questionnaires need to be developed and validated for these investigations. This has already begun in Germany with the establishment of the CU-KID Netzwerk (Email address: cu-kid@charite.de), the aim of which is to identify clinical centres and colleagues who treat children with urticaria and to initiate the information gathering described above.

The use of cyclosporine in dermatology: part I

Cyclosporine is a calcineurin inhibitor that acts selectively on T cells. It has been used in dermatology since 1997 for its US Food and Drug Administration indication of psoriasis and off-label for various other inflammatory skin conditions, including atopic dermatitis, blistering disorders, and connective tissue diseases. In the last decade, many dermatologists have hesitated to use this important drug in their clinical practices because of its toxicity profile. The purpose of this article is to review the mechanism of action of cyclosporine and its current uses and dosing schedules. It is our goal to create a framework in which dermatologists feel comfortable and safe incorporating cyclosporine into their prescribing regimens.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to describe the mechanism of action of cyclosporine, recognize the potential role of cyclosporine in dermatology and the evidence to support this role, and incorporate cyclosporine into his or her prescribing regimens.

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2009

This review highlights some of the research advances in anaphylaxis and hypersensitivity reactions to foods, drugs, and insects, as well as advances in allergic skin disease that were reported in the Journal in 2009. Among key epidemiologic observations, several westernized countries report that more than 1% of children have peanut allergy, and there is some evidence that environmental exposure to peanut is a risk factor. The role of regulatory T cells, complement, platelet-activating factor, and effector cells in the development and expression of food allergy were explored in several murine models and human studies. Delayed anaphylaxis to mammalian meats appears to be related to IgE binding to the carbohydrate moiety galactose-alpha-1,3-galactose, which also has implications for hypersensitivity to murine mAb therapeutics containing this oligosaccharide. Oral immunotherapy studies continue to show promise for the treatment of food allergy, but determining whether the treatment causes tolerance (cure) or temporary desensitization remains to be explored. Increased baseline serum tryptase levels might inform the risk of venom anaphylaxis and might indicate a risk for mast cell disorders in persons who have experienced such episodes. Reduced structural and immune barrier function contribute to local and systemic allergen sensitization in patients with atopic dermatitis, as well as increased propensity of skin infections in these patients. The use of increased doses of nonsedating antihistamines and potential usefulness of omalizumab for chronic urticaria was highlighted. These exciting advances reported in the Journal can improve patient care today and provide insights on how we can improve the diagnosis and treatment of these allergic diseases in the future.

Pathogenesis of chronic urticaria

Chronic urticaria is defined as the presence of urticaria (hives) for at least 6 weeks with the assumption that it occurs daily or close to it. If we eliminate physical urticarias and urticarial vasculitis from consideration, the remainder can be divided into autoimmune chronic urticaria (45%) and idiopathic chronic urticaria (55%). The autoimmune subgroup is associated with the IgG anti-IgE receptor alpha subunit in 35-40% of patients and IgG anti-IgE in an additional 5-10%. These autoantibodies have been shown to activate blood basophils and cutaneous mast cells in vitro with augmentation of basophil activation by complement and release of C5a, in particular. Binding methods (immunoblot and ELISA) yield positives in many autoimmune diseases as well as occasional normal subjects or patients with other forms of urticaria but most such sera are non-functional. Activation of basophils or mast cells causing histamine release is quite specific for chronic urticaria and defines the autoimmune subgroup. Although pathogenicity is not formally proven, the antibodies cause wealing upon intradermal injection, and removal of the autoantibody leads to remission. A cellular infiltrate is seen to be characterized by mast cell degranulation and infiltration of CD4+ T lymphocytes, monocytes, neutrophils, eosinophils, and basophils. The intensity of the infiltrate and clinical severity of the disease (including accompanying angio-oedema) is more severe in the autoimmune subpopulation. This latter group also has a higher evidence of human leucocyte antigen DR alleles associated with autoimmunity and a 25% incidence of antithyroid antibodies with diagnosed hypothyroidism in some. Hypo-responsiveness of patients' basophils to anti-IgE and hyperresponsiveness to serum defines another subpopulation (at least 50%) that overlaps the idiopathic and autoimmune subgroups. Hypo-responsiveness to anti-IgE has been shown to be associated with elevated levels of cytoplasmic phosphatases that inhibit degranulation. Reversal of the abnormality is seen with disease remission. Further work will be needed to distinguish whether this is a cause or a consequence of persistent urticaria and to further assess the relationship (or lack thereof) of altered responsiveness (decreased or increased) with the presence or absence of activating autoantibodies.