Angioedema and emergency medicine: From pathophysiology to diagnosis and treatment

Angioedema is a self-limiting edema of the subcutaneous or submucosal tissues due to localised increase of microvascular permeability whose mediator may be histamine or bradykinin. Patients present to emergency department when angioedema involves oral cavity and larynx (life-threatening conditions) or gut (mimicking an acute abdomen). After initial evaluation of consciousness and vital signs to manage breathing and to support circulation if necessary, a simple approach can be applied for a correct diagnosis and treatment. Forms of edema such as anasarca, myxedema, superior vena cava syndrome and acute dermatitis should be ruled out. Then, effort should be done to differentiate histaminergic from non-histaminergic angioedema. Concomitant urticaria and pruritus suggest a histaminergic origin. Exposure to allergens and drugs (mainly ACE inhibitors and non steroidal anti-inflammatory drugs) should be investigated as well as a family history of similar symptoms. Allergic histaminergic angioedema has a rapid course (minutes) whereas non histaminergic angioedema is slower (hours). Since frequently the intervention needs to be immediate, the initial diagnosis is only clinical. However, laboratory tests can be subsequently confirmatory. Allergic angioedema is sensitive to standard therapies such as epinephrine, glucocorticoids and antihistamines whereas non histaminergic angioedema is often resistant to these drugs. Therapeutic options for angioedema due C1-inhibitor deficiencies are C1-inhibitor concentrates, icatibant and ecallantide. If these drugs are not available, fresh frozen plasma can be considered. All these medications have been used also in ACE inhibitor-induced angioedema with variable results thus they are not currently recommended whereas experts agree on the discontinuation of the causative drug.

[Angioedema]

Angioedema may be an overlooked common disease. Angioedema comprises the idiopathic, the allergic, pseudo allergic, the physical form as well as the hereditary form. Diagnosis is simple when symptoms are classical (lips, eyes and tongue) but might be missed if symptoms are nonspecific such as dizziness or dyspnoea. However, the most striking observation reviewing the literature is the absence of original research on angioedema considering the high prevalence of the disease. From a patient and physician perspective more information and research on angioedema is needed.

Epidemiology of angioedema without wheals in an allergy and immunology center

We describe the diagnostic epidemiology, the clinical course, the family history and the response to treatment of patients with angioedema without wheals (AWW) at an Allergy and Immunology Clinical Center. We reviewed the case records of all patients at our office from January 1997 to April 2013. We recorded sex, age, age at onset of symptoms, family history of angioedema, number of visits to the office, type of angioedema, and response to treatment from those patients with angioedema without wheals. We classified angioedema according to its pathophysiology. We also describe those patients with angioedema mimics. From a total of 17,823 new patients, 303 had a presumptive diagnosis of angioedema without wheals. Twenty-three patients had an angioedema mimic. Forty percent were male and 60% were female. Average age at first visit was 40.6. Average number of visits was 2.4. Fifty-seven patients referred a family history. We attributed idiopathic angioedema to 55.7% of patients, 24.3% were drug related, 15.7% were due to C1 inhibitor deficiency, 2.1% were drug related+idiopathic angioedema, 1.4% were type III and 0.7% had exercise-induced angioedema. Ninety six percent of 53 evaluable idiopathic angioedema patients referred a benefit with anti-histamine therapy. AWW was a rare cause of consultation. Most of our patients had anti H1 responsive idiopathic angioedema and none had allergic angioedema. Women cases prevailed over men's. Family history and average age of onset of symptoms were different among the different types of angioedema.

[Angioedema]

Angioedema may be an overlooked common disease. Angioedema comprises the idiopathic, the allergic, pseudo allergic, the physical form as well as the hereditary form. Diagnosis is simple when symptoms are classical (lips, eyes and tongue) but might be missed if symptoms are nonspecific such as dizziness or dyspnoea. However, the most striking observation reviewing the literature is the absence of original research on angioedema considering the high prevalence of the disease. From a patient and physician perspective more information and research on angioedema is needed.

Consensus statement on the diagnosis, management, and treatment of angioedema mediated by bradykinin. Part I. Classification, epidemiology, pathophysiology, genetics, clinical symptoms, and diagnosis

BACKGROUND

There are no Spanish guidelines or consensus statement on bradykinin-induced angioedema.

AIM

To review the pathophysiology, genetics, and clinical symptoms of the different types of bradykinin-induced angioedema and to draft a consensus statement in light of currently available scientific evidence and the experience of experts. This statement will serve as a guideline to health professionals.

METHODS

The consensus was led by the Spanish Study Group on Bradykinin-Induced Angioedema (SGBA), a working group of the Spanish Society of Allergology and Clinical Immunology. A review was conducted of scientific papers on different types of bradykinin-induced angioedema (hereditary and acquired angioedema due to C1 inhibitor deficiency, hereditary angioedema related to estrogens, angioedema induced by angiotensin-converting enzyme inhibitors). Several discussion meetings of the SGBA were held in Madrid to reach the consensus.

RESULTS

The pathophysiology, genetics, and clinical symptoms of the different types of angioedema are reviewed. Diagnostic approaches are discussed and the consensus reached is described.

CONCLUSIONS

A review of bradykinin-induced angioedema and a consensus on diagnosis are presented.

[Increasing incidence of angioedema without urticaria--clinical features]

The causes of angioedema (AE), a self-limited, localized swelling of subcutaneous tissue or mucosa unaccompanied by urticaria, are diverse. The commonly applied label of "allergic" is frequently wrong and standard anti-allergic therapy can be ineffective. Types of AE could be categorized according to mediators which mediate vascular leakage: bradykinin AE (hereditary, acquired, angiotensin-converting enzyme inhibitor (ACEi)-related), histamine AE (allergic etiology), and various mediators mediated AE (pseudoallergic reaction to non-steroidal anti-inflammatory drugs). Idiopathic AE is a poorly understood syndrome. The growing relevance of AE without urticaria has been highlighted; angioedema is the most common cause of hospital admission among all acute allergic diseases. The diagnosis of AE is based on the presence of family history (hereditary), absence of family history with the onset during or after the fourth decade of life (acquired C1lnh deficiency), and treatment with ACEi (ACEi-related angioedema). About 0.1%-0.7% of patients taking ACEi develop angioedema as a well-documented but still frequently unrecognized side effect of drugs. Laboratory diagnosis is enabled by measuring serum levels of C1lnh antigen or C1lnh function. Type 1 (hereditary angioedema (HAE) was diagnosed when both antigenic and functional levels of C1lnh were below 50% of normal, and type 2 when functional levels of C1lnh were low, along with antigenic levels normal or higher. ACEi-related AE is diagnosed when AE recurs during therapy and disappears upon withdrawal. Symptoms may appear several years after therapy introduction. Severe acute attacks should be treated with C1lnh concentrate and icatibant, a selective and specific antagonist of bradykinin B2 receptors. Prophylaxis with attenuated androgens (danazol, stanazolol, oxandrolone) is effective in preventing symptom development.

[The multiple etiologies of angioedema]

Angioedema is a frequent disorder with multiple aetiologies. Angioedemas associated with urticaria are usually caused by histamine release and respond to anti-histamines and adrenalin. They include allergic angioedemas, anaphylactoid reactions (mostly drug-induced, e.g. NSAID), physical angioedemas and recurrent idiopathic angioedema. Bradykinin probably plays a causative role in the pathogenesis of ACE-inhibitor or angiotensin II receptor blocker related angioedemas, as well as in the pathogenesis of the rare hereditary or acquired C1-inhibitor deficiency angioedemas. Urticaria is then typically absent and anti-histamines, as well as adrenalin, are ineffective.

[Practical management of C1 inhibitor deficiency]

C1 inhibitor deficiency is a rare syndrome clinically characterized by recurrent episodes of swelling of subcutaneous tissue or angioedema. It can involve the skin, upper respiratory airways and abdomen. There are two main types: hereditary and acquired. Angioedema can involve practically any part of the cutaneous surface, it can cause lethal laryngeal edema and can present as gastrointestinal obstruction. The attacks can be triggered, in general, by trauma, drugs or infections. Diagnosis is confirmed by decreased serum levels of C4 and absence or marked decrease of the level or function of C1 inhibitor. Commonly employed drugs for prophylaxis and treatment of these patients include anabolic steroids, antifibrinolytic agents, and infusion of C1 inhibitor concentrate. Fresh frozen plasma is an option to be considered for short term prophylaxis or treatment of the acute attack. It is convenient to know this syndrome as it is a potentially life-threatening disease. Diagnosis of this rare syndrome is based on clinical features and characteristic alterations of laboratory tests. The acute attack should be treated as quickly as possible. Prophylactic therapy is indicated in certain circumstances (dental procedures, oral surgery).

Angioedema without urticaria: a large clinical survey

BACKGROUND

Angioedema without major urticarial flares (hives) is poorly understood. Its causes are diverse, and little is known about its pathogenic mechanisms. We report on our 11 years of experience with this condition and propose a classification of patients affected by angioedema unaccompanied by urticaria.

METHODS

From 1993 through 2003 at our outpatient clinic, 929 consecutive patients were examined for recurrent angioedema unaccompanied by urticaria. A detailed history was taken to identify known causes of angioedema, with special attention to external allergenic agents. Each patient underwent a complete physical examination, routine laboratory tests (blood cell count, protein electrophoresis, erythrosedimentation rate, examination of stool for ova and parasites, pharyngeal and urine cultures, sinus and dental radiography, and measurements of antitissue autoantibodies and rheumatoid factor in plasma), and complement parameters (C1 inhibitor, C4 and C1q). Further testing was done when pertinent, based on clinical findings. When all results were negative, response to H1-antihistamine was considered.

RESULTS

Angioedema could not be classified in 153 patients who were lost to follow-up (16.4%). Among the 776 cases with adequate data, these types of angioedema were identified: 124 (16%) related to external agents such as a drug, insect bite or foodstuff; 85 (11%) related to treatment with angiotensin-converting enzyme inhibitor; 55 (7%) associated with an autoimmune disease or infection; and 197 (25%) caused by C1 inhibitor deficiency. In the other 315 cases (41%), the etiology was undiscovered: 254 cases (33% of the study sample) were idiopathic histaminergic; 40 (5%) were idiopathic nonhistaminergic; and 21 (3%) had other causes of peripheral or generalyzed edema.

INTERPRETATION

Our data indicated that angioedema without urticaria could be classified according to specific clinical and pathogenic characteristics, and we have suggested a work-up for patients experiencing this condition.

Hereditary angioedema

Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by a C1-inhibitor deficiency. It is characterized by potentially life-threatening recurrent episodes of angioedema of the skin and mucosa. Several recent studies have further elucidated the immunology of HAE implicating bradykinin, the key mediator of the contact system. This article reviews the pathophysiology, subtypes, and clinical features of HAE. Therapeutic approaches for various clinical situations (emergency and prophylactic regimens) are also discussed.

Hereditary angioedema: new findings concerning symptoms, affected organs, and course

PURPOSE

Hereditary angioedema (HAE) due to C1 inhibitor deficiency is clinically characterized by relapsing skin swellings, abdominal pain attacks, and life-threatening upper airway obstruction. Our aim was to examine a temporal and spatial pattern of the edema episodes by evaluating the long-term course of hereditary angioedema in order to establish a specific swelling pattern.

SUBJECTS AND METHODS

Data were generated from 221 patients with C1 inhibitor deficiency by asking them about symptoms they experienced during their edema episodes. Documentation was accomplished through the use of standardized questionnaires.

RESULTS

A total of 131110 edema episodes were observed. Clinical symptoms started at a mean age of 11.2 (SD 7.7) years. During the following cumulative 5736 years, only 370 (6.5%) symptom-free years occurred. Skin swellings, including extremity, facial, genital, and trunk swellings, and abdominal attacks occurred in 97.4% of all edema episodes of the disease. The other episodes were laryngeal edema (0.9%); edema of the soft palate (0.6%); tongue swellings (0.3%); headache episodes (0.7%); episodes affecting urinary bladder (0.3%), chest (0.2%), muscles (0.4%), joints (0.1%), kidneys (0.1%), and esophagus (0.05%), and were partly combined with other edema episodes. The per-patient analysis and the per-episode analysis revealed markedly discrepant results. On average, women had a more severe course of the disease than men. Patients with early onset of clinical symptoms were affected more severely than those with late onset.

CONCLUSION

The described swelling pattern is specific for HAE and allows a tentative diagnosis based on clinical symptoms and the course of the disease.

[Analysis of the prevalence of subtypes of urticaria and angioedema]

BACKGROUND

The prevalence of various subtypes of urticaria in Japan has not been analyzed.

METHODS

We have classified 260 (105 males and 155 females) out patients with urticaria based on the classification in Guidelines for the diagnosis and treatment of urticaria and angioedema" prepared by the Japanese Dermatological Association with slight modification.

RESULTS

The urticaria in 200 out of 260 (76.9%) patients was idiopathic, and 101 (38.8%) patients showed more than one type of urticaria or angioedema. Among 146 patients with chronic urticaria, 90 (61.6%) were complicated by other types of urticaria; 59 (40.4%) by factitia, 29 (19.9%) by angioedema, and 12 (8.2%) by other types of urticaria. Deep pressure urticaria has been assumed as a rare type of urticaria in Japan, but was diagnosed in 5 patients with other types of urticaria.

CONCLUSION

Most of the subtypes of urticaria could be diagnosed mainly by history and physical examinations. Correct diagnosis of the subtypes of urticaria should be the basis of better understanding and the treatment of this disease.

[Hereditary angioedema. A report of a case and literature review]

Hereditary angioedema is a congenital disorder with recurrent attacks of localized swelling of submucosal and subcutaneous tissue, or both caused by a deficiency of the plasma protein C1 inhibitor. It is caused by heterozygous defects in the C1 inhibitor gene located on chromosome 11q, and it has an autosomal dominant inheritance pattern. This disease afflicts 1 in 10,000 to 1 in 150,000 persons. Hereditary angioedema has been reported in all races, and no sex predominance has been found. Skin and visceral organs may be involved by the typically massive local edema. The most commonly involved viscera are the respiratory and gastrointestinal systems, and it can affect the upper airways resulting in severe life-threatening symptoms, including the risk of asphyxiation. There are three types of hereditary angioedema, which difference lies in the inheritance pattern and in the C1 esterase inhibitor and C4 concentrations. The treatment is complicated and it should be treated with intravenous purified C1 inhibitor concentrate; corticosteroids, antihistamines and epinephrine can be useful adjuncts but they are not effective. We report a patient with hereditary angioedema type 1 and make a review of the medical literature.

[Urticaria and angioedema. An internal disorder with cutaneous manifestation]

Urticaria and angioedema will affect 15-20% of the general population during their lifetime, and this remains one of the most vexing conditions to evaluate and treat. This review of the literature is to give the reader a global insight into the spectrum of urticaria and angioedema, focusing on differential diagnosis and pathogenic mechanisms. It will define the role of the mast cell, exploring a possible autoimmune basis for urticaria. Last, the different potential treatments will be discussed. Urticaria and angioedema are frustrating problems for both physicians and their patients; however, the problem may best be approached by considering urticaria as a general affection rather than a specific cutaneous disease. The physical examination and medical history remain the two most important pieces of information.

[Determination of the functional activity, amount of C1 inhibitor, and autoantibodies as a tool for differential diagnosis of angioedema]

Aetiology of angioedema (and therefore the scheme of its treatment) can be different. Angioedema may be subdivided into four categories: hereditary and acquired angioedemas, allergies and vasculitis. To establish the reason of the hereditary and acquired form of angioedema analyses of functional activity of complement components, quantities and activity of C1 inhibitor, presence (or absence) autoantibodies to C1 inhibitor allow. Sorption of the puried enzymes of activated subcomponent C1s or plasmin on micropanels allows to connect specifically in cells of plate C1 inhibitor from serum and with the help conjugate of antibodies against C1 inhibitor with a horse-radish peroxidase to determine quantity of connected functionally active C1 inhibitor. Addition of this test-system ELISA system for determination of quantitative contents of C1 inhibitor in serum, and also systems for definition IgG, IgA and IgM autoantibodies against C1 inhibitor finishes creation of a necessary set of methods of differential diagnostics.

[Profhylaxis and treatment of hereditary and acquired angioedema at HUB; use of the C1-esterase inhibitor]

INTRODUCTION

Hereditary and acquired angioedema result from a deficiency in first complement component esterase (C1-esterase) inhibitor. It is characterized by transient subcutaneous tissue, intestinal wall, and upper airway swelling, which may lead to asphyxia and death. The pathophysiology, classification, diagnosis, and treatment of this condition are discussed, as is the follow-up of patients diagnosed with angioedema who received 1 vial of concentrated C1-INH (Berinert); the contribution of the Pharmacy Department in the dispensation and control of said drug is also assessed.

MATERIAL AND METHODS

PubMed and other relevant sources were searched. Patient, dispensation, and Berinert(R) indication data were collected from controlled prescriptions; follow-up was completed by performing a medical history, collecting laboratory data, and patient interview when needed.

RESULTS

Eight out of 9 cases were of hereditary angioedema, and 1 case was of acquired angioedema. Danazol was used as long-term prophylaxis in 8 patients, but side effects forced discontinuation in some of them. The C1-INH concentrate was effective in 6 acute episodes that were detected during the study, as well as in 3 surgical prophylaxis cases (overall use 6,500 U).

CONCLUSION

Danazol was effective as prophylactic treatment, but had severe side effects. The C1-INH concentrate was effective both as prophylactic therapy and treatment for acute episodes. An adequate stock of this product will be available at the Pharmacy Department.

Clinical and aetiological aspects in urticaria and angio-oedema

BACKGROUND

Urticaria is a common disorder that affects as many as 20% of all people at some time during their lifetime.

OBJECTIVES

To analyse the prevalence of various forms of urticaria according to an aetiological and clinical classification, we carried out a 4-year study in an outpatient clinic.

METHODS

The study was carried out on 562 consecutive patients (178 males and 384 females; mean age 35.4 +/- 16), who had been referred to our unit for the study of urticaria and angio-oedema. Baseline investigations included: the patient's family and personal history of allergy; duration of symptoms, presence of associated symptoms and objective signs of the current episode; clinical, laboratory and instrumental investigations; assessment of response to antihistamine treatment.

RESULTS

A family history of atopy was present in 35% of patients and a personal history of allergy in 24%. We subdivided urticaria and angio-oedema into several groups on the basis of their clinical and aetiological aspects. Of the 562 patients, 424 (76%) presented with ordinary urticaria (43 acute urticaria, 311 chronic urticaria, 70 episodic urticaria), 80 (14%) physical urticaria, 49 (9%) angio-oedema without weals, six (1%) IgE-mediated contact urticaria and three (0.5%) urticarial vasculitis. In 64 cases (11%) urticaria/angio-oedema was associated with one or more symptoms. We identified 394 cases (82%) of idiopathic urticaria, 42 (9%) of immunological urticaria, 29 (6%) of non-immunological urticaria and 17 (3%) of urticaria secondary to infections. Of the treated subjects, 54% showed a good response to treatment with antihistamines.

CONCLUSIONS

Our data provide an overview of urticaria/angio-oedema in a large series of patients, based on clinical-aetiological aspects, and related to recent diagnostic guidelines.

[Urticaria and angioedema]

Urticaria is a common complaint characterized by the eruption of cutaneous wheals, accompanied by redness and itching and in which mast cells are thought to play a central role. Wheals range from a few millimeters to several centimeters in diameter and are usually short lasting, except in case of urticarial vasculitis in which they last longer than 24 hours. Urticaria may occur alone or be associated with angioedema, that can be defined as a deep dermal and subcutaneous edema typically affecting the lips, face, hands, feet, penis or scrotum. Angioedema may also involve the submucosal tissue, and when the swellings occur in the oropharynx they can be alarming and occasionally life-threatening. In many cases the cause of acute urticaria or angioedema may be determined, whilst the pathogenetic and diagnostic aspects of the chronic forms are more complex and variable. The clinical features of, as well as the diagnostic and therapeutic approaches to the different forms of urticaria and angioedema are here reviewed, focusing on chronic idiopathic urticaria.

Five novel mutations in the C1 inhibitor gene (C1NH) leading to a premature stop codon in patients with type I hereditary angioedema

Hereditary angioedema (HAE) is a disorder characterised by recurrent attacks of localized subcutaneous or submucosal edema. It is inherited in an autosomal dominant fashion and caused by a deficiency of C1 inhibitor (C1 inh, or C1NH). Most patients with HAE have an absolute deficiency of C1 inh (type I HAE) while the rest (15% of kindreds) synthetize a dysfunctional C1 inh protein (type II HAE). In this report a novel use of denaturing gradient gel electrophoresis (DGGE) followed by direct sequencing of the C1 inhibitor gene is presented. Five novel mutations, one nonsense (p.S48X) and four small deletions resulting in frameshifts (g.2264-2265delAG, g.2304delC, g.8493-8494delCC and g.16676-16677delTG) have been identified in the C1 inhibitor gene in five families with type I HAE. All of these mutations lead to premature termination of translation and thus can be considered causative of the C1 inh deficiency. Moreover, two previously described mutations in the reactive center of C1 inh, p.R444C and p.R444H, have been detected in four unrelated patients with type II HAE.

A review of the reported defects in the human C1 esterase inhibitor gene producing hereditary angioedema including four new mutations

C1 esterase inhibitor (C1INH) is an important regulatory protein of the classical pathway of complement. Mutations in the gene for this protein cause the autosomal dominant disorder hereditary angioedema (HAE). Approximately 85% of patients with HAE have a Type I defect, characterized by a diminished level of antigenic and functional C1INH. Patients with Type II defects have sufficient protein, but one allele produces dysfunctional protein. We have sequenced the DNA from HAE patients and have discovered four previously unreported mutations. The first mutation is a splice site error at nucleotide 8721, which changes the 3' acceptor splice site AG to GG at the end of intron 5 at nucleotide 8721-8722. The second mutation is a single base insertion in exon 3 between nucleotides 2467 and 2468. The third mutation is a missense error present in the eighth exon of the C1INH; at nucleotide 16867 (amino acid 470), a T to A mutation transforms a Met to a Lys. The fourth mutation closely resembles the third mutation in that it is a missense error occurring in exon 8 in the distal hinge region; a T16827C substitution changes the Phe at amino acid 457 to Leu. This report compiles a list of 97 distinct defects in the C1INH gene that cause hereditary angioedema.

Acquired angioedema with C1 inhibitor deficiency: is the distinction between type I and type II still relevant?

BACKGROUND

Acquired angioedemas are divided into type I associated with lymphoproliferation and type II caused by anti-C1-inhibitor antibodies. Recent reports have suggested that this distinction is not so clear-cut, mainly because of the presence of antibodies against the C1 inhibitor in some cases belonging to the type I group. We report herein 2 additional cases of acquired angioedema with anti-C1-inhibitor antibody.

MATERIAL AND METHODS

One man and 1 woman had had acquired angioedema for several years. In the man, a monoclonal component had been detected several years before the present study. In the second patient, a monoclonal component was detected during the study. The following data were studied on successive blood samples collected during angioedema manifestations: complement component levels, functional activity of the classical pathway, functional and antigenic C1 inhibitor doses, ELISA test to detect autoantibodies to C1 inhibitor and Western blot analysis of the C1 inhibitor.

RESULTS

In both patients, CH50 and C4 activities were decreased, and an autoantibody to C1 inhibitor was detected. In 1 case, the antibody appeared after the monoclonal component; in the second case, it appeared before and belonged to a different immunoglobulin class.

CONCLUSION

Our data suggest that the distinction between type I and type II acquired angioedema is no longer valid because of overlapping in some cases.

Predicting airway risk in angioedema: staging system based on presentation

Angioedema is an immunologically mediated, anatomically limited, nonpitting edema that can lead to life-threatening airway obstruction. To predict the risk of airway compromise in angioedema, we retrospectively reviewed 93 episodes in 80 patients from 1985 to 1995. Intubation or tracheotomy was necessary in 9 (9.7%) cases. Angiotensin-converting enzyme inhibitor use in 36 cases (39%) was associated with intensive care unit (ICU) admission (P = 0.05). ICU stay correlated significantly with presentation with voice change, hoarseness, dyspnea, and rash (P < 0.05). Voice change, hoarseness, dyspnea, and stridor were present in patients requiring airway intervention (P < 0.05). On the basis of our data, we propose a staging system by which airway risk may be predicted from the anatomic site of presentation. Patients with facial rash, facial edema, lip edema (stage I), and soft palate edema (stage II) were treated as outpatients and on the hospital ward. Patients with lingual edema (stage III) usually required ICU admission. All patients with laryngeal edema (stage IV) were admitted to the ICU. Airway intervention was necessary in 7% of stage III patients and in 24% of stage IV cases. No deaths were caused by angioedema. Airway risk in angioedema may be predicted by anatomic site of presentation, allowing appropriate triage with preparation for airway intervention in selected cases.

[Round Table: Urticaria and angioedema: introduction and classification]

Urticaria and angioedema are common diseases in children and adults. Approximately 15-25% of the population will have urticaria or angioedema at least once in their life-time. Urticaria is characterized as the appearance of erythematous, circumscribed, elevated, pruritic, edematous swelling of the upper dermal tissue. Erythematous swelling of the deeper cutaneous and subcutaneous tissue is called angioedema. In angioedema lesions are less pruritic but pain and burning are common. Urticaria may occur in any part of the body, whereas angioedema often involves face, extremities or genitalia. In contrast to other forms of edema there are not symmetric distribution. Urticaria and angioedema are often associated. Urticaria is considered acute if symptoms are present for less than 6 weeks, but usually in childhood lesions disappear in a few days. In chronic urticaria symptoms are longer than 6 weeks; if the episodes were of shorter duration than the symptoms-free periods urticaria is considered recurrent. Acute urticaria has been reported to be the common type in childhood and chronic urticaria is more frequent in adults. Acute urticaria is usually a self-limited benign disease in young children. Nevertheless it is an uncomfortable nuisance, interfering daily activities and sleep, and produces psychosocial impact in patients and parents (an altered self-image is always an alarming situation). Urticaria is a frequent cause of emergency room visit but few patients need to be admitted. Urticaria has long been believed to be an allergic disease but clinically it has rare been proved to be so. The basic mechanism involves the release of diverse vasoactive mediators that arise from the activation of cells or enzymatic pathways. Histamine is the best known of these substances, and elicits the classic triple response consisting of vasodilatation (erythema), increased vascular permeability (edema) and an axon reflex that increases reaction. In contrast to simple symptoms and easy diagnosis of urticaria, etiologic factors are often difficult to establish. Urticaria can be classified according to the eliciting factors and the different pathomechanisms. According to several works, clinical history carried out by a trained physician can be regarded as the most valuable diagnostic tool and extensive screening test do not contribute to etiologic diagnosis of urticaria. Only a few specific tests appeared to be valuable at this respect. In different studies about children urticaria, the most common etiological factors have been identified as infection, physical urticaria, food allergy, drug adverse reaction, parasitic infestation and papular urticaria. The aim of this work-shop is to define, describe and discuss these frequent problems.

Impaired production of both normal and mutant C1 inhibitor proteins in type I hereditary angioedema with a duplication in exon 8

In the autosomal dominant disorder type I hereditary angioedema, reduced levels of C1 inhibitor may be due in part to increased turnover and decreased synthesis of normal C1 inhibitor protein. A type I hereditary angioedema patient was recently described in whom the C1 inhibitor mutation consisted of a 20-bp duplication of nucleotides 1414 to 1433 in exon 8 that introduced a frame shift predicting the loss of a normal stop codon and the translation of a protein 52 amino acids longer than normal. In this study, we analyzed the expression of C1 inhibitor in fibroblasts obtained from a skin biopsy of this patient. Two proteins of approximately 78 and 94 kDa were found intracellularly, corresponding to the products of normal and mutated alleles, respectively. Pulse-chase analysis showed a complete lack of secretion of the mutated form. In addition, there was decreased extracellular production of the normal C1 inhibitor, suggesting either decreased secretion or increased intracellular catabolism of the normal protein because of the presence of the mutant allele. The production of other complement proteins was normal. This study provides a model for further analysis of autosomal dominant genetic disorders in which production of the functional protein may be affected by the product of the mutated allele.

C-1-inhibitor binding monoclonal immunoglobins in three patients with acquired angioneurotic edema

The syndrome of acquired angioneurotic edema (AAE) is characterized by the adult onset of angioedema, the lack of evidence for inheritance of the disorder, and the frequent association of the C1-inhibitor (C1-INH) deficiency with lymphoproliferative or other malignant diseases. Recently, a new type of AAE (type II AAE) has been described. The two major biologic differences of this new syndrome compared with all other previously reported AAE cases (type I AAE) are the presence in patients' sera of both anti-C1-INH autoantibodies, often monoclonal, and a circulating low molecular weight (95 kd) C1-INH protein. From the clinical point of view, the absence of underlying lymphoproliferative disease is the hallmark of type II AAE compared with type I AAE. However, the distinction between type I and type II AAE may not be so clear-cut. We report three patients with monoclonal gammopathies and AAE for whom the initial diagnosis was type I AAE. The demonstration by ELISA of the C1-INH binding ability of their monoclonal immunoglobulins in addition to the presence of 95 kd C1-INH protein enables us to change the diagnosis to type II AAE. From the therapeutic point of view, it is crucial to detect the anti-C1-INH antibody and to analyze the C1-INH size to distinguish type I and type II AAE, especially if patients have a monoclonal gammopathy, to give the appropriate treatment (attenuated androgens vs immunosuppressive regimen, respectively) to prevent a fatal outcome.

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.

[Immunologic studies in chronic urticaria]

Chronic urticaria is considered to be a heterogeneous disease, which can be divided into several subclasses. The authors investigated 126 patients suffering from chronic urticaria with 41 of unknown origin. The aim of the present study was to work out a strategy for the complete investigation of patients with chronic urticaria. The findings of the immunological study modified the results obtained by medical assessment of the 126 chronic urticaria cases, diminished the number of the patient with chronic urticaria unknown etiology.

Unique C1 inhibitor dysfunction in a kindred without angioedema. II. Identification of an Ala443-->Val substitution and functional analysis of the recombinant mutant protein

We have determined the cause of an unusual C1 inhibitor abnormality in a large kindred. We previously found that half of serum C1 inhibitor molecules in affected kindred members are normal. The other half complexed with C1s but showed little complex formation with C1r. These molecules also appeared to be relatively resistant to digestion by trypsin. Taken together, the findings suggested that members of this kindred are heterozygous for an unusual C1 inhibitor mutation. Sequencing of genomic DNA from the kindred revealed that thymine has replaced cytosine in the codon for Ala443 (P2 residue) in one C1 inhibitor allele, resulting in substitution with a Val residue. To test the effect of this substitution, a mutant C1 inhibitor containing Ala443-->Val was constructed by site-directed mutagenesis and expressed in COS-1 cells. Both the Ala443-->Val mutant and the wild-type C1 inhibitor complexed completely with C1s, kallikrein, and coagulation Factor XIIa after incubation at 37 degrees C for 60 min. In contrast, the mutant inhibitor failed to complex completely with C1r under the same conditions. Time course analysis showed that the ability of the mutant to complex with C1s is also impaired: although it complexed completely in 60 min, the rate of complex formation during a 0-60-min incubation was decreased compared with wild-type C1 inhibitor. The mutant inhibitor also formed a complex with trypsin, a serine protease that cleaves, and is not inhibited by, wild-type C1 inhibitor. The Ala443-->Val mutation therefore converts C1 inhibitor from a substrate to an inhibitor of trypsin. These studies emphasize the role of the P2 residue in the determination of target protease specificity.

Crucial residues in the carboxy-terminal end of C1 inhibitor revealed by pathogenic mutants impaired in secretion or function

The last exon of the C1-1NH gene was screened for point mutations in 36 unrelated hereditary angioedema patients. Mutations were found in eight patients, predicting changes in the short COOH-terminal region which anchors the reactive site loop on its COOH-terminal side. The effects of each of these mutations were examined in transiently transfected Cos-7 cells. Complete intracellular retention or degradation was observed with substitutions in the COOH-terminal strands 4B or 5B: Leu459-->Pro, Leu459-->Arg, and Pro467-->Arg were all blocked at early stages of intracellular transport, but differences in the immunofluorescence patterns indicated that a significant fraction of the Leu459-->Pro and of the Pro467-->Arg proteins reached a compartment distinct from the endoplasmic reticulum. In line with previous findings with alpha 1-antitrypsin, chain termination within strand 5B resulted in rapid degradation. Mutant Val451-->Met, in strand 1C, and mutant Pro476-->Ser, replacing the invariant proline near the COOH terminus, yielded reduced secretion, but these extracellular proteins were unable to bind the target protease C1s. Presence of low levels of both dysfunctional proteins in patient plasmas defies the conventional classification of C1 inhibitor deficiencies as type I or type II. These data point to a key role of certain residues in the conserved COOH-terminal region of serpins in determining the protein foldings compatible with transport and proper exposure of the reactive site loop.

Type II hereditary angioedema: presentation and follow-up of three cases

Three cases with a family history of type II hereditary angioedema (HAE) are presented, together with their progress following treatment with stanozolol. The development of patients with this drug was satisfactory in clinical terms, as it gave rise to virtually no side effects or angioedema episodes. Only patient 3 showed an elevation of hepatic enzyme (SGOT, SGPT) levels in serum, 2 months after starting treatment. C4 values of patient 2 attained sporadic normalization in the first five months of treatment, while the values corresponding to the other two patients remained below normal at all times. The activity of C1 inhibitor (C1-INH) remained below normal in all three cases. In patient 3, it was observed that circulating immunocomplex (CIC) monitoring was, together with clinical progress, a useful method for controlling HAE activity.

Contiguous deletion and duplication mutations resulting in type 1 hereditary angioneurotic edema

Mutations that cause low antigenic and functional levels of C1 inhibitor protein result in type 1 hereditary angioneurotic edema. This disease is characterized by episodic edema leading to considerable morbidity and sometimes death. We present here two novel mutations in the reactive center coding region. One mutation is a deletion of an imperfect palindrome encompassing nucleotides 1395-1428 and the other is a direct duplication of nucleotides 1414-1433. These mutations do not depend on improper pairing of direct repeats, but may form as a consequence of a peculiar consensus sequence or an alternative secondary structure.

[Classification of urticaria and genetic angioedema]

Urticaria and genetic angioedema may be divided into three groups, according to their pathogenesis: anomaly of the complement system, physical origin or metabolic origin. Recent developments essentially concern hereditary angio-oedema, with location of the gene of the inhibitor of C1 esterase on chromosome 11 and the discovery of deletions or mutations of this gene in affected families.

Hereditary angioedema type II--a study of two families

Hereditary angioedema (HA) is caused by a quantitative or qualitative deficiency of C1 esterase inhibitor (C1 INH). We present a study of nine patients with HA belonging to two different families. The symptoms started before 10 years of age in most cases (78%). Facial edema (lips, eyes) and of the extremities (feet, hands) were the most frequent complaints. Three patients presented edema of the glottis and one of them underwent a tracheostomy twice. Laboratory tests, outside the acute crisis, revealed low levels of C4 in all patients. The serum levels of C1 INH were normal in seven patients; however, functional activity was not observed in any of them. After the use of a modified androgen (danazol), control of symptoms was observed in all patients, although functional activity was re-established in only five patients.

Peripheral edema due to increased vascular permeability: a clinical appraisal

The release of vasoactive substances produces reversible changes of endothelial permeability with consequent edematous syndromes. We present 899 patients referred to our clinic for "non-hydrostatic non-hyponcotic" recurrent edema problems. Personal and family histories were recorded and a complete physical examination was carried out for each patient. In chronic situations laboratory tests [blood cell count, cryoglobulins, thyroid hormones, complement components (C3, C4, C1 inhibitor), total IgE, skin testing] were performed. Four subgroups of angioedema are identified for relevant clinical and etiopathogenetic differences. Seventy-three percent of patients had an urticaria-angioedema syndrome responding to antihistamine and/or corticosteroid treatment (histamine-dependent angioedema). Twenty-three percent had an angioedema related to a deficiency in C1 esterase inhibitor (complement-dependent angioedema). In a minority of patients, angioedema was due to the pharmacological effect of a drug (pharmacological angioedema) or was of a totally unknown origin (idiopathic angioedema). A generalized increase in vascular permeability was reported in 3 patients (systemic capillary leak syndrome). A brief survey of the literature is given with the review of our patients.

Rapid and sensitive techniques for identification and analysis of 'reactive-centre' mutants of C1-inhibitor proteins contained in type II hereditary angio-oedema plasmas

Novel procedures for structural analysis of the 'reactive-centre' residues, particularly the P1 residue, of the dysfunctional C1-inhibitor proteins found in the plasmas of type II hereditary angio-oedema (HAE) patients are described. C1-inhibitor is adsorbed directly from plasma on to Sepharose-anti-(C1 inhibitor) beads. The P1 residue of C1 inhibitor is arginine and hence a potential cleavage site for trypsin. Thus trypsin digestion of the immobilized protein, followed by SDS/PAGE of the released fragments, identifies P1 residue mutations. Pseudomonas aeruginosa elastase digestion of the immobilized protein, followed by purification of the released C-terminal peptide (by h.p.l.c.) and N-terminal sequence analysis defines the new P1 residue (or other mutations in the reactive-centre region). The techniques are both rapid and highly sensitive, requiring only 400 microliters of plasma. In addition, they permit accurate assessment of the level of normal (functional) inhibitor in a subclass of type II HAE plasmas, those containing P1-residue mutant proteins.

Chronic urticaria

Urticaria affects 15% to 20% of the population once or more during a lifetime. Chronic urticaria is a frequent recurrent eruption over a period greater than 6 weeks; the cause remains a mystery in more than 75% of cases. Urticaria and angioedema may be produced by immunologic or nonimmunologic means. Urticarial vasculitis, contact urticaria, mastocytosis, physical urticarias, dermatographism, cholinergic urticaria, localized heat urticaria, cold urticaria, aquagenic urticaria, and vibratory angioedema all require specific evaluation and treatment. Chronic idiopathic urticaria is usually controlled by antihistamines; depending on the circadian rhythm of the eruption, sedative or nonsedative antihistamines are prescribed. Some patients will require a combination of H1 and H2 antagonists, or even parenteral corticosteroids.

Molecular defects of the C1-inhibitor gene in hereditary angioedema

Family studies of hereditary angioedema are discussed with particular emphasis on the molecular basis of the more common form of the disease (type I), characterized by quantitative C1-Inhibitor deficiencies. Results obtained in several laboratories can be interpreted in the light of the restriction maps and of the exon-intron structure of the normal C1-Inhibitor gene that have been published recently. Several partial deletions of either exon 4 or exon 7 or of larger portions of the 5' end of the gene and a duplication of exon 4 have been described. These gene alterations are essentially family-specific and they account for at least fifteen-percent of the defects in type I hereditary angioedema. Detailed sequences analyses of cloned defective genes indicate that clusters of repetitive sequences of the Alu family, located within several introns, are responsible for the relatively high frequency of gross gene alterations observed at the C1-Inhibitor locus. In contrast, most of the defects that lead to production of dysfunctional proteins appear to be point mutations within the P1 residue of the reactive site, whose codon features a hypermutable CpG dinucleotide.

Current concepts of urticaria and angioedema

An operational classification based on immunoreactants provides insight to possible pathogenetic mechanisms participating in the genesis of urticaria and angioedema. Such an approach addresses the causes of urticaria and angioedema. Therapy can then be developed depending on the established mechanism-etiology. Unfortunately, in less than a third of the instances can a distinct etiology be established, but symptomatic therapy provides relief in a significant portion of such afflicted individuals.

[Hereditary angioedema. Effect of danazol on C4 and functional C1INH]

Hereditary angioedema (HAE) is an inherited deficiency of the inhibitor of C1 esterase (C1 inh). Two types of genetic C1 inh deficiency have been described, type I: quantitative, and type II: functional. For the purpose of the present study, 4 out of 51 HAE patients were selected. None of them had received any previous androgenic therapy. The group was integrated by two type I and one type II cases. All patients that entered in the protocol received 400 mg/day of danazol over 14 days. The complement system was evaluated by monitoring C4, Hemolytic complement 50% (CH50), Circulating Immune Complexes (CIC), and antigenic and functional C1 INH during the study. The level of the complement factors at the beginning and the end of this period demonstrated a statistically significant increase of C4 and CH50 and the disappearance of CIC, while C1INH remained unmodified. These results suggest that the therapeutic effect of Danazol may have two mechanisms of action: i. promotion of C4 synthesis by anabolic effect resulting in an improvement of the complement system with the disappearance of CIC, and ii, a minor increase of C1 inh level primarily due to the lack of its consumption.