Chronic idiopathic urticaria: profiles of skin mast cell histamine release during active disease and remission

Chronic Spontaneous Urticaria: Etiology and Pathogenesis

Urticaria, also known as hives, is a common condition thought to affect up to 20% of individuals worldwide in their lifetime. This skin condition is characterized by the appearance of pruritic, erythematous papules or plaques with superficial swelling of the dermis. The major complaint is the symptom of pruritus. Angioedema, which involves a deeper swelling of dermal or mucosal tissues, may accompany urticaria. Urticaria can be classified by both time course of symptoms and the underlying etiology.

Chronic urticaria and the pathogenic role of mast cells

The signs and symptoms of chronic urticaria (CU) are caused by the activation and degranulation of skin mast cells (MCs). Recent studies have added to our understanding of how and why skin MCs are involved and different in CU. Also, novel and relevant mechanisms of MC activation in CU have been identified and characterized. Finally, the use of MC-targeted and MC mediator-specific treatments has helped to better define the role of the skin environment, the contribution of specific MC mediators, and the relevance of MC crosstalk with other cells in the pathogenesis of CU. Here, we review these recent findings and their impact on our understanding of CU, with a focus on chronic spontaneous urticaria (CSU). Also, we highlight open questions, issues of controversy, and unmet needs, and we suggest what studies should be performed moving forward.

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

Objective

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

Methods

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

Results

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

Conclusion

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

Mast Cells in the Skin: Defenders of Integrity or Offenders in Inflammation?

Mast cells (MCs) are best-known as key effector cells of immediate-type allergic reactions that may even culminate in life-threatening anaphylactic shock syndromes. However, strategically positioned at the host–environment interfaces and equipped with a plethora of receptors, MCs also play an important role in the first-line defense against pathogens. Their main characteristic, the huge amount of preformed proinflammatory mediators embedded in secretory granules, allows for a rapid response and initiation of further immune effector cell recruitment. The same mechanism, however, may account for detrimental overshooting responses. MCs are not only detrimental in MC-driven diseases but also responsible for disease exacerbation in other inflammatory disorders. Focusing on the skin as the largest immune organ, we herein review both beneficial and detrimental functions of skin MCs, from skin barrier integrity via host defense mechanisms to MC-driven inflammatory skin disorders. Moreover, we emphasize the importance of IgE-independent pathways of MC activation and their role in sustained chronic skin inflammation and disease exacerbation.

How to Approach Chronic Inducible Urticaria

Chronic inducible urticaria (CIndU) is a group of chronic urticarias characterized by the appearance of recurrent wheals, recurrent angioedema or both, as a response to specific triggers. CIndU includes both physical (symptomatic dermographism, cold and heat urticaria, delayed pressure urticaria, solar urticaria, and vibratory urticaria) and nonphysical urticarias (cholinergic urticaria, contact and aquagenic urticaria). Here, we review the different forms of CIndU with an emphasis on symptomatic dermographism, cold urticaria, cholinergic urticaria, and delayed pressure urticaria. We discuss the clinical features, the diagnostic workup including provocation and threshold testing, and available treatment options.

Emerging Therapies in Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is characterized by typically short-lived and fleeting wheals, angioedema or both, which occur spontaneously and persist for longer than 6 weeks. This term is applied to the most common subtype of chronic urticaria. The underlying pathophysiology for CSU involves mast cell and basophil degranulation with release of histamine, leukotrienes, prostaglandins and other inflammatory mediators. Although a variety of treatments exist, many patients do not tolerate or benefit from the existing therapies and even require more effective treatments. Omalizumab is currently the only licensed biologic for antihistamine-refractory CSU, and novel drugs are under development. This article reviews its current status regarding pathogenesis and approach to treatment as well as therapeutic agents that are under development for the treatment of CSU.

Chronic Spontaneous Urticaria: The Devil's Itch

Chronic urticaria is defined as the presence of urticaria for a period exceeding 6 weeks, assuming symptoms for most days of the week. It is divided into chronic inducible urticarias and chronic spontaneous urticaria, previously termed chronic idiopathic urticaria. The latter designation emphasizes that patients can experience urticaria independent of any exogenous stimulus even if one can define circumstances that may worsen symptoms. A search for such an external "cause" is fruitless because the underlying abnormality is "intrinsic," whether it is autoimmune, or some unknown process. Approximately 40% of patients with chronic spontaneous urticaria report accompanying episodes of angioedema, whereas 10% have angioedema as their primary manifestation. In most cases, it is a self-limiting disorder, persisting for 2 to 5 years in most cases, although 20% of patients suffer for more than 5 years. The treatment that has evolved is largely empiric, based on double-blind, placebo-controlled studies whenever possible, but is not yet targeted to any particular pathogenic mechanism. In this article, we review the current status regarding pathogenesis, discuss the diagnostic workup, and update the approach to treatment including consideration of published guidelines, our own experience, and guideline updates that are being prepared.

Treatment of chronic spontaneous urticaria: Immunomodulatory approaches

This paper summarizes and reviews the mechanisms of action and data concerning efficacy of recommended treatments as well as other treatments that have been tested, independently of the outcomes, in the management of chronic spontaneous urticaria. Due to the central role of mast cells, basophils and histamine in the pathophysiology of this disease, H₁-antihistamines remain the first-line treatment. However, current knowledge about this complex disease, also recognizes an important role for T lymphocytes, B lymphocytes, and autoantibodies. Implications of these others mediators thus provide further targets for treatment. Indeed, agents previously used to treat other autoimmune and inflammatory diseases, have demonstrated efficacy in chronic spontaneous urticaria and are therefore potential therapeutic alternatives for antihistamine unresponsive patients.

Omalizumab treatment in patients with chronic inducible urticaria: A systematic review of published evidence

BACKGROUND

Omalizumab, a recombinant anti-IgE antibody, effectively treats chronic spontaneous urticaria. Evidence is lacking in patients with chronic inducible urticarias (CIndUs), which are frequently H₁-antihistamine resistant.

OBJECTIVE

From the current published literature, we aimed to determine the strength of evidence for omalizumab efficacy and safety in the treatment of CIndUs.

METHODS

We performed a PubMed search to identify evidence on omalizumab use in the following 9 CIndU subtypes: symptomatic dermographism, cold urticaria, delayed-pressure urticaria, solar urticaria, heat urticaria, vibratory angioedema, cholinergic urticaria, contact urticaria, and aquagenic urticaria.

RESULTS

Forty-three trials, case studies, case reports, and analyses were identified. Our review indicates that omalizumab has substantial benefits in patients with various CIndUs. The evidence is strongest for symptomatic dermographism, cold urticaria, and solar urticaria. Little/no evidence was available on vibratory angioedema and aquagenic and contact urticaria. Our review supports rapid onset of action demonstrated through early symptom control in most cases, sometimes within 24 hours. Many patients gained complete/partial symptom relief and substantially improved quality of life. Adverse events were generally low, with omalizumab being well tolerated by most patients, including children.

CONCLUSIONS

A strong body of evidence supports the use of omalizumab in the treatment of patients with therapy-refractory CIndU. More data from randomized controlled studies are warranted.

Mechanisms of action that contribute to efficacy of omalizumab in chronic spontaneous urticaria

The monoclonal anti-immunoglobulin E (IgE) antibody, omalizumab, was the first drug approved for use in patients with chronic idiopathic/spontaneous urticaria (CIU/CSU) who remain symptomatic despite H₁ -antihistamine treatment. Omalizumab binds to free IgE, which lowers free IgE levels and causes FcεRI receptors on basophils and mast cells to be downregulated. It has been shown to improve symptoms of CIU/CSU, but its mechanism of action is not currently understood. Potential mechanisms in CIU/CSU include reducing mast cell releasability, reversing basopenia and improving basophil IgE receptor function, reducing activity of IgG autoantibodies against FcεRI and IgE, reducing activity of IgE autoantibodies against an antigen or autoantigen that has yet to be definitively identified, reducing the activity of intrinsically 'abnormal' IgE, and decreasing in vitro coagulation abnormalities associated with disease activity. However, none of these theories alone or in combination fully account for the pattern of symptom improvement seen with omalizumab therapy, and therefore, no one mechanism is likely to be the definitive mechanism of action. Additional research is needed to further clarify the involvement of omalizumab in relieving symptoms associated with the complex, multifactorial pathogenesis of CIU/CSU.

Immunological events in chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is a highly debilitating skin disease associated with systemic features. We have made significant progress in several aspects relating to this condition. However, the exact physiopathology remains unknown. There is mounting evidence for an autoimmune basis, demonstrated by the CSU serum ability to activate healthy donors skin mast cells and blood basophils. However, it is only seen among 35–40% of patients. Mast cells and basophils play an important role in this skin condition. Both cells in CSU patients have unique features that differentiate them from basophils and mast cells from healthy donors. In the case of basophils, basopenia is typically found in CSU patients. Basophils from CSU patients also tend to be hyporesponsive to stimuli that act through the IgE receptor, responsive to other stimuli as MCP-1 or C5a, and hyperesponsive when incubated with sera. Eosinophils are also present in CSU skin biopsies, yet their exact role has not yet been defined. Likewise, endothelial cells also play a function, as indirectly demonstrated by an increase of vasoactive peptides in skin and plasma of CSU patients’ samples. All these facts orchestrate a systemic inflammation response producing a significant increase of several inflammatory markers. Unfortunately, we lack a unitary model that could explain the exact role of each of these players. In this review, we will describe the history and discover the pathway to the present knowledge on the immunological facts of this disease.

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.

The role of focal infections in the pathogenesis of psoriasis and chronic urticaria

INTRODUCTION

The Focal Infection Theory, originally presented at the beginning of the 20(th) century, postulates that systemic diseases can be caused by microorganisms that arise from the focus of infection. Foci of infections have been described as sinuses, adenoids, tonsils, teeth, genitourinary tract, gall bladder and kidneys. A focus of infection is defined as the area that can occur in any part of the body, contains a pathogen (microorganism) and is usually asymptomatic. There are discordant opinions about the role of focal infections in the pathogenesis of psoriasis and urticaria.

AIM

To establish whether there is a higher incidence of focal infections in patients with chronic urticaria and psoriasis.

MATERIAL AND METHODS

We retrospectively reviewed 129 patients with a history of psoriasis and chronic urticaria: 58 women and 71 men treated in the Department of Dermatology of the Jagiellonian University Medical College in Krakow.

RESULTS

In the analyzed group, 11 patients had a dental consultation, 58 - laryngological consultation and 29 women had a gynecological consultation. The most common examples of focal infection were tonsillitis, upper respiratory tract infections, sinusitis, dental caries and genitourinary tract infections. Aggravating factors were similar to previously described.

CONCLUSIONS

A high incidence of focal infections in patients with psoriasis and urticaria suggests that infections may play a significant role in the pathogenesis of these skin disorders. Treatment of infection foci may play the key role in the remission of skin changes.

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

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

Diagnosis and treatment of urticaria and angioedema: a worldwide perspective

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

Basophil responsiveness in chronic urticaria

Chronic urticaria is a common skin disease without an etiology in the majority of cases. The similarity of symptoms and pathology to allergen-induced skin reactions supports the idea that skin mast cell and blood basophil IgE receptor activation is involved; however, no exogenous allergen trigger has been identified. Recent evidence supports a role for blood basophils in disease expression. Specifically, blood basopenia is noted in active disease with the recruitment of blood basophils to skin lesional sites. In addition, blood basophils display altered IgE receptor-mediated degranulation that reverts in disease remission. In active chronic idiopathic urticaria (CIU) subjects, changes in IgE receptor-signaling molecule expression levels accompany the altered degranulation function in blood basophils. The arrival of therapies targeting IgE has further shown that altered blood basophil degranulation behavior has potential use as a disease biomarker in CIU.

Cultured peripheral blood mast cells from chronic idiopathic urticaria patients spontaneously degranulate upon IgE sensitization: Relationship to expression of Syk and SHIP-2

Recently, signaling changes in the FcvarepsilonRI pathway involving inositol lipid phosphatases have been identified in the basophils of chronic idiopathic urticaria (CIU) subjects. Based on the profile of basophil FcvarepsilonRI-mediated histamine degranulation, we have segregated CIU subjects into two groups, CIU Responder (CIU R) or CIU Nonresponder (CIU NR). In the present study, we compared expression of SHIP-1, SHIP-2, and Syk protein to histamine release (HR) from mast cells (MC) cultured from the peripheral blood of CIU R, CIU NR, and normal subjects. The MC of CIU R donors contained significantly increased Syk and decreased SHIP-2 as compared to CIU NR (Syk: p=0.038, SHIP-2: p=0.038) and normals (Syk: p=0.042, SHIP-2: p=0.027). Spontaneous HR from CIU donors was increased two-fold compared to normals (p=0.04). In summary, our results suggest a possible predilection for urticarial MC to spontaneously degranulate upon IgE sensitization contributing to the increased pruritus associated with CIU.

New concepts in chronic urticaria

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

Pathophysiology of chronic urticaria

OBJECTIVE

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

DATA SOURCES

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

STUDY SELECTION

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

RESULTS

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

CONCLUSION

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

Urticaria

Urticaria with or without angioedema is frequently encountered in primary care medicine. Although many patients and physicians think that urticaria is evidence of an IgE-mediated allergic reaction, often the etiology of urticaria is unknown. This uncertainty frequently results in patients enduring unnecessary lifestyle changes or extensive testing. In more persistent cases, patients achieve control of their disease only with the use of more toxic medications, such as corticosteroids, and this can lead to a range of systemic complications. Acute urticaria is typically due to a hypersensitivity reaction while chronic urticaria has a more complex pathogenesis. Antihistamines remain the mainstay of symptomatic treatment for both.

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.

Basophils and mast cells in chronic idiopathic urticaria

Chronic idiopathic urticaria (CIU) is diagnosed in patients when urticarial eruptions recur for more than 6 weeks, and no specific cause is determined. Given that urticaria resembles the lesions induced by injection of histamine or allergen into the skin, a role for mast cells or basophils has been proposed in the generation of localized urticarial lesions. However, currently, the exact mechanisms governing regional mast cell or basophil activation are unknown. In the past decade, there has been mounting interest in viewing CIU as an autoimmune disease, given the presence of circulating autoantibodies to IgE or the alpha subunit of the high-affinity IgE receptor (FceRI) in a subset of patients. In this review, we propose that in addition to autoantibodies, specific differences in the expression of FceRI-signaling molecules in the basophils or mast cells of CIU patients may contribute to the generation of urticarial eruptions.

Comparative evaluation of Type 1 latex hypersensitivity in patients with chronic urticaria, rubber factory workers and healthy control subjects

Latex hypersensitivity manifests itself most commonly with contact urticaria. In this study, we investigated the frequency of latex hypersensitivity as a possible aetiological factor in patients with chronic urticaria (CU) and compared latex hypersensitivity of CU patients (n = 50) with that of rubber factory workers (n = 50) and healthy controls (n = 50). Prick test with latex and fruit extracts and determination of latex-specific immunoglobulin E (IgE) were performed. As a risk factor, contact dermatitis due to rubber additives was tested by patch test. Latex hypersensitivity was detected in 14% of CU patients, 12% of rubber factory workers and 12% of healthy controls (P > 0.05). Positive patch test with rubber additives was detected in 6% of CU and 4% of rubber factory workers. 3 of 7 CU patients had sensitivity to fruits in addition to latex hypersensitivity. In 1 patient with CU, the clinical complaints were found to be related to latex hypersensitivity. These findings suggest that the frequency of latex hypersensitivity in CU patients is no higher than that in healthy individuals. However, CU patients should be carefully asked about latex allergy, as we demonstrated that 1 of the CU patients had undiagnosed symptomatic latex allergy.

Interstitial cystitis and bladder mastocytosis in a woman with chronic urticaria

A patient with chronic urticaria and angioedema developed endoscopically confirmed interstitial cystitis. Bladder biopsy revealed bladder mastocytosis with > 60 mast cells/mm2 (normal < 10) in the detrusor and submucosa. Most of the mast cells were activated and degranulated. The occurrence of IC in a patient with urticaria and angioedema, diseases both associated with mast cell pathophysiology, supports the role of mast cells in interstitial cystitis.

Comparison of histamine-releasing factor recovered from skin and peripheral blood mononuclear cells of patients with chronic idiopathic urticaria

BACKGROUND

The pathogenesis of chronic idiopathic urticaria is characterized by defective histamine release. Skin mast cells show an increased release of histamine while circulating basophils are less responsive to immunologic stimulus.

OBJECTIVE

The purpose of the study was to examine and compare the production of the histamine-releasing factor in the skin and within the peripheral blood of patients with chronic idiopathic urticaria and normal control subjects, as a possible factor responsible for the difference observed in the releasability of both skin mast cells and basophils.

METHODS

Using the skin chamber technique, histamine-releasing factor production and histamine concentration were assessed in normal-appearing skin of patients with chronic idiopathic urticaria (n = 12) and normal controls (n = 5) over a 2-hour observation period. In both groups, histamine-releasing factor production by peripheral blood mononuclear cells was also measured.

RESULTS

The weighted average of histamine-releasing factor production during the 2-hour observation period was higher in the non-lesional skin of patients with chronic idiopathic urticaria as compared with normal controls (5.6 +/- 1.4% versus 0.7 +/- 0.6%, P < .01). In contrast, less histamine-releasing factor was produced by peripheral blood mononuclear cells in chronic urticaria as opposed to normal controls (17.2 +/- 2.1% versus 25.7 +/- 2.8%, P < .03). Spontaneous histamine concentration was not significantly different in patients with chronic urticaria than in normal controls.

CONCLUSION

Histamine-releasing factor production is increased in the skin, and decreased in the peripheral blood of patients with chronic idiopathic urticaria when compared with nonatopic controls. The lower production of histamine releasing factor in the blood could be explained by the migration of activated T-lymphocytes in the skin.

Allergen-induced histamine release in intact human skin in vivo assessed by skin microdialysis technique: characterization of factors influencing histamine releasability

BACKGROUND

The purposes of the study were to characterize allergen-induced histamine release in intact human skin in vivo by using a novel microdialysis technique and to study covariates influencing histamine releasability.

METHODS

Hollow microdialysis fibers were inserted into the upper dermis in 15 timothy-sensitivity subjects. Up to 12 fibers were inserted in each subject. Each fiber was perfused with Krebs-Ringer's solution at a rate of 3.0 microliters/min. Three to four serial dilutions of allergen were applied to the skin by intracutaneous injections or skin prick test above individual fibers. Samples were collected in two 2-minute fractions before skin challenge and in 10 consecutive samples for 20 minutes after skin challenge. Histamine was assayed spectrofluorometrically.

RESULTS

A significant dose-response relationship for histamine release was demonstrated with intracutaneous tests and skin prick tests. The time to reach peak histamine release after an intracutaneous test was 4 to 8 minutes, compared with 12 to 14 minutes for a skin prick test. Histamine release correlated significantly with wheal size. Intrasubject coefficient of variation on histamine release was about 20%. A substantial intersubject variation in histamine releasability was observed. Seventy to seventy-five percent of the variation could be accounted for by a combination of gender, total and allergen-specific IgE, and an in vitro basophil histamine release test.

CONCLUSIONS

Using a skin microdialysis technique, we have described in detail histamine release in intact human skin by allergen. The microdialysis method proved to be a reproducible technique for monitoring histamine release in allergic skin reactions and for studying histamine releasability of skin mast cells in vivo.

Urticaria, angioedema, and rheumatologic disease

Urticaria and angioedema are common processes that are experienced by 15% to 25% of the population at least once during a lifetime. This article presents an overview of urticaria and angioedema with emphasis on these processes as they relate to rheumatic disease. Discussion includes classification of urticaria and angioedema and recommended evaluation and treatment of patients presenting with such problems.

Comparison of serum histamine-releasing activity and clinical manifestations in chronic idiopathic urticaria

We found increased serum histamine-releasing activity (HRA) in 27% of patients with chronic idiopathic urticaria. Patterns of clinical manifestations were similar in those with and without serum HRA, including responses to a standard treatment regimen. In HRA+ patients the degree of serum HRA generally correlated with clinical disease activity.

Codeine-induced histamine release in intact human skin monitored by skin microdialysis technique: comparison of intradermal injections with an atraumatic intraprobe drug delivery system

BACKGROUND

The skin microdialysis technique makes it possible to measure histamine release in intact human skin in vivo directly. In this study we have used the microdialysis technique to characterize histamine release by codeine after intracutaneous injections and following skin challenge by a novel atraumatic delivery technique.

OBJECTIVE

The purpose of the study was to compare histamine release in human skin by codeine, delivered by an intraprobe drug delivery system (IPD) and intracutaneous injections (ICT), with respect to dose-response relations, kinetics of histamine appearance and decay, correlations between histamine release and skin responses, and reproducibility.

METHODS

Hollow dialysis fibres were inserted intradermally in 12 healthy subjects. Twelve fibres were inserted in each subject, six fibres in each arm. Each fibre was perfused at a rate of 3 microM/min, and samples were collected in 2 min fractions. By the IPD technique, codeine was administered to the skin by adding codeine to the perfusion medium. Sequential IPD challenges were performed in one arm, and ICTs were done on the other arm.

RESULTS

Sixfold serial dilutions of codeine (0.01-3 mg/mL) caused a significant dose-related histamine release by ICT and IPD. Peak histamine release was found within the first 4 min after skin challenge by ICT and IPD, followed by a fast decline with a dialysate histamine half life of approximately 2-3 min. Peak histamine release was linearly correlated with cumulative release of the 20 min sampling period, and histamine release correlated with weal size. The coefficient of variation on peak histamine release was 18.9% and 4.8% for codeine ICT and IPD, respectively.

CONCLUSION

We have described in detail codeine-induced histamine release in intact human skin in vivo by the microdialysis technique. It was possible to administer codeine atraumatically to the skin by intraprobe delivery. The skin microdialysis technique opens up possibilities for measurement of inflammatory mediators release in normal and diseased skin, and it will be possible to deliver immunopharmacologically active drugs to the skin by intraprobe delivery.