Inibidor de C1 esterase derivado do plasma humano via intravenosa para o tratamento de crises de angioedema hereditário em pacientes com dois anos ou mais de idade / C1 esterase inhibitor derived from human plasma intravenously for the treatment of hereditary angioedema crises in patients with two or more years of age

INTRODUÇÃO: O angioedema hereditário (AEH) é uma doença genética ultrarrara, potencialmente fatal e subdiagnosticada. É uma imunodeficiência primária do sistema complemento, e foi classificado como um erro inato da imunidade em decorrência da deficiência de inibidor de C1 esterase (C1-INH), proteína que controla as vias de ativação do complemento. A alteração do C1-INH leva ao aumento da produção de bradicinina que, por sua vez, causa vasodilatação, aumento da permeabilidade dos vasos e extravasamento de plasma. A classificação mais atualizada do AEH agrupa os pacientes naqueles com deficiência do inibidor da C1-esterase (C1-INH), codificado pelo gene SERPING1 e naqueles C1-INH normal (anteriormente denominado de tipo III). Os pacientes com mutação do SERPING1 podem apresentar uma deficiência quantitativa do C1-INH (AEH tipo I) ou uma proteína anômala que resulta em deficiência funcional do C1-INH (tipo II). O diagnóstico é realizado através do exame clínico (anamnese, exame físico e quadro clínico) e laboratorial (dosagem de C4 e de C1-INH), além de teste genético (presença de mutação patogênica em SERPING1) para confirmação. O AEH não tem cura, porém há opções terapêuticas para a profilaxia e controle das crises agudas. Conforme o atual Protocolo Clínico e Diretrizes Terapêuticas (PCDT) de Angioedema associado a deficiência de C1 esterase (C1-INH), o tratamento das crises agudas é realizado em ambiente hospitalar, com uso de plasma fresco congelado, caso exista o risco de asfixia para o paciente. O plasma fresco congelado não foi testado em ensaios clínicos quanto à sua eficácia e segurança nas crises de AEH, e sua administração oferece não apenas a reposição do C1-INH, mas também os substratos nos quais ess

The Mortality from Hereditary Angioedema Worldwide: a Review of the Real-World Data Literature.

This study aims to review the global mortality secondary to laryngeal edema in patients diagnosed with hereditary angioedema and their relatives over the years, as well as to describe epidemiological and clinical findings associated with this outcome. An extensive search of the literature was made in PubMed, Scopus, and Embase to identify mortality rates secondary to laryngeal edema in patients with hereditary angioedema. The search was carried out in September of 2020 and in April of 2021, and keywords based on the MeSH terms were searched in three databases. The filter of language was used for finding only articles in English, and there was no limit to the year of publication. A total of twenty-three articles fulfilled the inclusion criteria for review and data extraction. The analyzed studies included 3292 patients and 411 deaths from asphyxia due to laryngeal edema. One hundred and three deaths in close relatives were described as secondary to the same cause. The main findings were summarized in tables: year and place of publication, the number of patients and deaths from laryngeal edema, patients previously diagnosed, and death age. Death rates from laryngeal edema had an average of one death for every 20 patients. Eight studies reported deaths in relatives. For every 7.4 patients in these studies, one relative died. The percentage among deaths in general associated with laryngeal edema was evaluated in three studies (32.7%, 44.4%, and 56%). The high frequency of this outcome suggests that deaths still occur, and improvement of hereditary angioedema treatment still needs to be met.

An ABC of the Warning Signs of Hereditary Angioedema.

Hereditary angioedema (HAE) with C1 inhibitor deficiency is a genetic disorder that clinically manifests with attacks of angioedema in the subcutaneous and submucosal tissues, mainly in the extremities, abdomen, and upper airway. During attacks, vascular permeability is increased due to increased bradykinin (BK). This means that special therapies are needed for attacks that do not respond to traditional antiallergic therapies involving antihistamines, corticosteroids, and epinephrine. The recurring attacks may disable patients and lead to frequent visits to emergency rooms where misdiagnoses are common. HAE attacks may be fatal when upper-airway edema occurs, if proper treatment with a C1 inhibitor concentrate or BK receptor antagonist is not administered or an emergency tracheostomy is not performed. We propose a mnemonic method for the warning signs of HAE for the use as a diagnostic tool, i.e., the so-called "ABC" of the warning signs of HAE. The letters represent the following: A = Angioedema, B = Bradykinin, C = C1 inhibitor, D = Distress factors, E = Epinephrine nonresponsive, F = Family history, and G = Glottis/Gastrointestinal edema. To avoid fatalities, medical staff and patients, including family members, must be aware of HAE. An alphabetical mnemonic method has been developed and we hope it may benefit patients.

New mutations in SERPING1 gene of Brazilian patients with hereditary angioedema.

Hereditary Angioedema is an autosomal dominant inherited disease leading to oedema attacks with variable severity and localization predominantly caused by C1-INH deficit. More than 400 mutations have been already identified, however no genetic analysis of a Brazilian cohort of HAE patients with C1-INH deficiency has been published. Our aim was to perform genetic analysis of C1-INH gene (SERPING1) in Brazilian HAE patients. We screened the whole SERPING1 coding region from 30 subjects out of 16 unrelated families with confirmed diagnosis of HAE due to C1-INH deficiency. Clinical diagnosis was based on symptoms and quantitative and/or functional analysis of C1-INH. We identified fifteen different mutations among which eight were not previously described according to databases. We found five small deletions (c.97_115del19; c.553delG; c.776_782del7; c.1075_1089del15 and c.1353_1354delGA), producing frameshifts leading to premature stop codons; seven missense mutations (c.498C>A; c.550G>C; c.752T>C; c.889G>A; c.1376C>A; c.1396C>T; c.1431C>A); one nonsense mutation (c.1480C>T), and two intronic alterations (c.51+1G>T; c.51+2T>C). Despite the small number of participants in this study, our results show mutations not previously identified in SERPING1 gene. This study represents the first Brazilian HAE cohort evaluated for mutations and it introduces the possibility to perform genetic analysis in case of need for differential diagnosis.

Angioedema hereditario en Medellín, Colombia: evaluación clínica y de la calidad de vida / Hereditary angioedema in Medellín (Colombia): Clinical evaluation and quality of life appraisal

Introducción. El angioedema hereditario es una inmunodeficiencia primaria de carácter autosómico dominante, debida a un déficit en la proteína inhibidora del factor C1 y caracterizada por episodios recurrentes de edema subcutáneo y de las mucosas. Las impredecibles y frecuentes crisis de angioedema afectan la calidad de vida de los individuos que las padecen. Objetivo. Analizar las características clínicas de una familia con un caso índice de angioedema hereditario y determinar el impacto de la enfermedad en la calidad de vida. Materiales y métodos. En el estudio se incluyeron 26 miembros de la familia, a 25 de los cuales se les midieron los niveles sanguíneos del factor C4 del complemento y del inhibidor de C1 antigénico y funcional. Se utilizaron dos instrumentos, el SF-36 para evaluar la salud del adulto y el KIDSCREEN-27 para la calidad de vida de niños y adolescentes. Resultados. El 83 % de los individuos que reportaron síntomas cumplían con los criterios serológicos del angioedema hereditario de tipo I: valores bajos del factor C4 del complemento y del inhibidor de C1 cuantitativo (antigénico) y cualitativo (funcional). Se encontró que la calidad de vida en cuanto al bienestar psicológico y el desempeño emocional de los pacientes, se veía considerablemente afectada por los síntomas de la enfermedad. Conclusión. Este estudio provee información sobre la primera familia caracterizada con angioedema hereditario de tipo 1 en el Valle de Aburrá, Colombia. Aunque para ello se usó un instrumento genérico, se confirmó, además, el efecto negativo de la enfermedad en la calidad de vida de los individuos que la padecen.

Introduction: Hereditary angioedema is an autosomal dominant primary immunodeficiency caused by a deficiency of the C1 inhibitor protein and characterized by recurrent episodes of subcutaneous and mucosal edema. Unpredictable and frequent crisis of angioedema affect the quality of life of individuals suffering this kind of disorder. Objective: To analyze the clinical characteristics of a family with an index case of hereditary angioedema and to determine the impact of this disease on their quality of life. Materials and methods: Twenty six members of the family were included in the trial; 25 of them were analyzed for C4 complement and antigenic and functional C1 inhibitor blood levels. Two instruments (SF-365 and KIDSCREEN-27) were used to evaluate adult health quality and children and teenagers quality of life, respectively. Results: Eighty three percent (83%) of individuals reporting symptoms of the condition exhibited serological criteria of hereditary angioedema type I: low levels of both C4 complement and quantitative (antigenic) and qualitative (functional) C1 inhibitor. In relation to patients' psychological and emotional performance, their quality of life was significantly affected by the symptoms of hereditary angioedema. Conclusion: This study provides evidence of the first family in Valle de Aburrá (Colombia) characterized as having hereditary angioedema type I. Despite the use of a generic instrument, the negative impact on the quality of life of individuals suffering this disease was also confirmed.

Coagulation Factor XII Gene Mutation in Brazilian Families with Hereditary Angioedema with Normal C1 Inhibitor.

BACKGROUND: Hereditary angioedema (HAE) with normal C1 inhibitor (C1-INH) is a rare disorder. Mutations of the gene encoding coagulation factor XII have been identified in a subset of patients with this condition. Our aim was to investigate mutations in the F12 gene in patients with HAE with normal C1-INH from Brazil. METHODS: We studied 5 Brazilian families with index female patients who presented with recurrent angioedema with normal C1-INH and C4 levels. Genomic DNA was isolated from whole blood and PCR was performed. Mutations were detected by the sequencing of exon 9 of the F12 gene and allelic discrimination. RESULTS: The c.983C>A (p.Thr328Lys) mutation was identified in 16 subjects, from 4 of the 5 families studied, including 8 patients with symptoms of HAE with normal C1-INH (87.5% women) and 8 subjects asymptomatic for HAE (25% women). Mean age at onset of symptoms among the FXII-HAE patients was 13.8 years (range 6-25 years). Recurrent abdominal pain (100%) and subcutaneous angioedema (87.5%) were the most frequent clinical presentations. Two patients presented with associated laryngeal edema. In keeping with previous observations in patients with both C1-INH-HAE and HAE with normal C1-INH, all 7 women with FXII-HAE reported triggering or worsening of symptoms upon intake of estrogen-containing oral contraceptives and/or pregnancy. CONCLUSIONS: We report for the first time in Brazil a mutation in the F12 gene as a likely cause of HAE with normal C1-INH in patients with recurrent attacks of angioedema and/or abdominal pain. A higher frequency of abdominal pain attacks and onset of symptoms at a younger age were observed among Brazilian patients when compared to those from other parts of the world.

[Hereditary angioedema in Medellín (Colombia): Clinical evaluation and quality of life appraisal]. / Angioedema hereditario en Medellín, Colombia: evaluación clínica y de la calidad de vida.

INTRODUCTION: Hereditary angioedema is an autosomal dominant primary immunodeficiency caused by a deficiency of the C1 inhibitor protein and characterized by recurrent episodes of subcutaneous and mucosal edema. Unpredictable and frequent crisis of angioedema affect the quality of life of individuals suffering this kind of disorder. OBJECTIVE: To analyze the clinical characteristics of a family with an index case of hereditary angioedema and to determine the impact of this disease on their quality of life. MATERIALS AND METHODS: Twenty six members of the family were included in the trial; 25 of them were analyzed for C4 complement and antigenic and functional C1 inhibitor blood levels. Two instruments (SF-365 and KIDSCREEN-27) were used to evaluate adult health quality and children and teenagers quality of life, respectively. RESULTS: Eighty three percent (83%) of individuals reporting symptoms of the condition exhibited serological criteria of hereditary angioedema type I: low levels of both C4 complement and quantitative (antigenic) and qualitative (functional) C1 inhibitor. In relation to patients' psychological and emotional performance, their quality of life was significantly affected by the symptoms of hereditary angioedema. CONCLUSION: This study provides evidence of the first family in Valle de Aburrá (Colombia) characterized as having hereditary angioedema type I. Despite the use of a generic instrument, the negative impact on the quality of life of individuals suffering this disease was also confirmed.

A single nucleotide deletion at the C1 inhibitor gene as the cause of hereditary angioedema: insights from a Brazilian family.

BACKGROUND: Hereditary angioedema is an autosomal dominant disease characterized by episodes of subcutaneous and submucosal edema. It is caused by deficiency of the C1 inhibitor protein, leading to elevated levels of bradykinin. More than 200 mutations in C1 inhibitor gene have been reported. The aim of this study was to analyze clinical features of a large family with an index case of hereditary angioedema and to determine the disease-causing mutation in this family. METHODS: Family pedigree was constructed with 275 individuals distributed in five generations. One hundred and sixty-five subjects were interviewed and investigated for mutation at the C1 inhibitor gene. Subjects reporting a history of recurrent episodes of angioedema and/or abdominal pain attacks underwent evaluation for hereditary angioedema. RESULTS: We have identified a novel mutation at the C1 inhibitor gene, c.351delC, which is a single-nucleotide deletion of a cytosine on exon 3, resulting in frameshift with premature stop codon. Sequencing analysis of the hypothetical truncated C1 inhibitor protein allowed us to conclude that, if transcription occurs, this protein has no biological activity. Twenty-eight members of the family fulfilled diagnostic criteria for hereditary angioedema and all of them presented the c.351delC mutation. Variation in clinical presentation and severity of disease was observed among these patients. One hundred and thirty-seven subjects without hereditary angioedema did not have the c.351delC mutation. CONCLUSION: The present study provides definitive evidence to link a novel genetic mutation to the development of hereditary angioedema in patients from a Brazilian family.

[Hereditary angioedema. A report of a case and literature review]. / Angioedema hereditario. Comunicación de un caso y revisión de la bibliografía.

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.

Angioedema hereditário: intervenções iatrogênicas - Caso clínico comentado / Hereditary angioedema: iatrogenic interventions

Objetivo: Apresentar o caso clínico de um paciente com dor abdominal recorrente submetido a quatro intervenções cirúrgicas no período de cinco meses. Descrição: Paciente masculino, 31anos, com história de dor abdominal recorrente desde os sete anos de idade que motivou diversos atendimentos em serviço de emergência. Nos cinco meses que antecederam a consulta em nosso serviço foi submetido a quatro laparotomias exploradoras sem conclusão diagnóstica, além de referir emagrecimento de 30 kg. Foram dosadas as concentrações séricas do inibidor de C1 esterase (C1-INH) e do quarto componente do complemento (C4), e ambas estavam reduzidas. Iniciado tratamento com hormônio androgênio atenuado, houve melhora clínica, e atualmente está assintomático.Comentários: Trata-se de um caso de angioedema hereditário (AEH) com predomínio de manifestações gastrintestinais. O retardo no diagnóstico provocou a realização desnecessária de quatro intervenções cirúrgicas, que resultaram em desnutrição e perda de qualidade de vida. O AEH deve ser incluído entre os diagnósticos diferenciais de dor abdominal recorrente com o objetivo de evitar intervenções cirúrgicas iatrogênicas nestes pacientes.

[Therapeutic approach of hereditary angioedema]. / Angioedema hereditário: considerações sobre terapia.

PURPOSE: Hereditary Angioedema was first described by William Osler in 1888 and it is caused by a hereditary or acquired deficiency of C1 esterase inhibitor (C1-INH). Treatment is indicated for acute attacks or prophylaxis of angioedema which occur in the subcutaneous tissue respiratory or gastrointestinal tracts. Treatment includes attenuated androgens, inhibitors of kininogen or plasminogen, like tranexamic acid or e-aminocaproic acid and the administration of C1-INH concentrate. We describe the peculiarities of the treatment chosen for 10 patients (4 families) with HAE and their evolution. METHODS: Ten patients (1-38 years old) with HAE were diagnosed by clinical history and laboratory evaluation. The following tests were performed for the complement system: C1-INH, C4 and C3 levels and hemolytic assay (CH50 and APH50) for the classic and alternative pathways. Treatment was initiated considering severity of symptoms, age, gender and therapeutic response of the patient. RESULTS: Clinical evaluation showed: 4/10 patients with recurrent subcutaneous edema; 3/10 with previous laryngeal edema and 3/10 with sporadic symptoms. Different severity of symptoms was verified in the same family. The laboratory evaluation detected: low C1-INH levels (10/10); low serum C4 level (8/10); undetectable CH50 (3/10) and low CH50 levels (6/10); low APH50 levels (2/10). Six out of ten patients did not receive any specific treatment and 2 of them had high risk of asphyxia. One adolescent had been controlled with e-aminocaproic acid, one child had been changed from danazol to tranexamic acid, a 30 year old female patient had received oxandrolone and a 38 year old man had been treated with danazol. CONCLUSIONS: Although HAE is caused by the same defect and affects members of the same family, various approaches have been taken to treat these patients. We observed different alternatives of prophylactic therapy for HAE, of which some did not require drug therapy.

Angioedema hereditário: considerações sobre terapia / Therapeutic approach of hereditary angioedema

OBJETIVOS: A primeira descrição clínica completa do angioedema hereditário (HAE) foi relatada por William Osler, em 1888. As formas de angioedema com deficiência de C1-INH são divididas em hereditárias e adquiridas. A terapêutica pode ser direcionada aos ataques agudos ou profilaxia de novos episódios. O tratamento de escolha é feito através de hormônios masculinizantes, podendo também ser indicado os inibidores da ativação do cininogênio e do plasminogênio como o ácido tranexâmico ou o ácido e-aminocapróico e a reposição de concentrado de C1-INH. O presente estudo relata a evolução de 10 pacientes (quatro famílias) acometidos por HAE e as peculiaridades do tratamento utilizado em cada caso. MÉTODOS: Dez pacientes (1-38 anos) com HAE foram diagnosticados através de história clínica e exames laboratoriais. Os testes realizados para avaliação do sistema complemento foram: dosagem sérica de C1-INH, C4 e C3 e ensaio hemolítico (CH50 e APH50) para as vias clássica e alternativa. O tratamento foi indicado de acordo com a gravidade dos sintomas, idade, sexo e resposta terapêutica. RESULTADOS: A avaliação clínica evidenciou 4/10 pacientes com edema subcutâneo recorrente; 3/10 pacientes com edema de laringe prévio e 3/10 pacientes com sintomas esporádicos. Sintomas de gravidade diferentes foram evidenciados na mesma família. A avaliação laboratorial (dosagem sérica) demonstrou: níveis de C1-INH diminuídos em 10/10; níveis diminuídos de C4 8/10; níveis indetectáveis de CH50 em 3/10 e diminuídos em 6/10; níveis diminuídos de APH50 em 2/10. 6/10 pacientes não receberam tratamento específico, sendo que dois deles apresentam alto risco para asfixia; uma adolescente tem sido controlada com ácido e-aminocapróico, uma criança que fazia uso de danazol passou a receber ácido tranexâmico, uma paciente de 30 anos recebe oxandrolona e um homem de 38 anos está em tratamento com danazol. CONCLUSAO: Apesar do HAE ser causado pelo mesmo defeito e acometer membros da mesma família, diferentes critérios têm sido estabelecidos para o tratamento desses pacientes. Foram indicados diferentes esquemas terapêuticos para HAE e alguns dos pacientes puderam ser seguidos sem terapia medicamentosa.

Glycosaminoglycans affect the interaction of human plasma kallikrein with plasminogen, factor XII and inhibitors.

Human plasma kallikrein, a serine proteinase, plays a key role in intrinsic blood clotting, in the kallikrein-kinin system, and in fibrinolysis. The proteolytic enzymes involved in these processes are usually controlled by specific inhibitors and may be influenced by several factors including glycosaminoglycans, as recently demonstrated by our group. The aim of the present study was to investigate the effect of glycosaminoglycans (30 to 250 micro/ml) on kallikrein activity on plasminogen and factor XII and on the inhibition of kallikrein by the plasma proteins C1-inhibitor and antithrombin. Almost all available glycosaminoglycans (heparin, heparan sulfate, bovine and tuna dermatan sulfate, chondroitin 4- and 6-sulfates) reduced (1.2 to 3.0 times) the catalytic efficiency of kallikrein (in a nanomolar range) on the hydrolysis of plasminogen (0.3 to 1.8 microM) and increased (1.9 to 7.7 times) the enzyme efficiency in factor XII (0.1 to 10 microM) activation. On the other hand, heparin, heparan sulfate, and bovine and tuna dermatan sulfate improved (1.2 to 3.4 times) kallikrein inhibition by antithrombin (1.4 microM), while chondroitin 4- and 6-sulfates reduced it (1.3 times). Heparin and heparan sulfate increased (1.4 times) the enzyme inhibition by the C1-inhibitor (150 nM).

Angioedema hereditário: quantos diagnósticos foram perdidos? / Hereditary angiodema: how many diagnosis were lost?

Objetivo: Apresentar uma imunodeficiência rara, o angioedema hereditário, descrita em cerca de 2 (per cent) dos pacientes com angioedema. A herança é autossômica dominante e quando não tratada pode causar óbito em 25 (per cent) dos pacientes. Método: Levantamento bibliográfico sobre os aspectos do angioedema hereditário, comentando-se em particular o caso de uma paciente e a demora de seu diagnóstico. Resultado: O diagnóstico da doença geralmente ocorre após os 30 anos de idade, devido as crises serem mais intensas e freqüentes. Conclusão: O angioedema hereditário deve ser considerado desde cedo no diagnóstico diferencial do angioedema, para propiciar controle do quadro clínico, diminuição das complicações da doença e melhor qualidade de vida ao paciente.

Hereditary angioedema. Long-term follow-up of 88 patients. Experience of the Argentine Allergy and Immunology Institute.

Since the detection of the first patient with hereditary angioedema (HA) in 1978, 88 new patients belonging to 16 families have been referred to our clinic. Eighty patients had Type I disease, 5 Type II, and 3 Type III (secondary). We describe the clinical onset, frequent complications, diagnostic tests of the complement system, and abnormalities of the coagulation pathway linked to complement activation. Particular attention was paid to family members who could present succedaneum symptoms. The results of danazole and other therapies and protective and preventive treatment for surgery also are discussed.

Human homozygous type I plasminogen deficiency and ligneous conjunctivitis

On the basis of a questionnaire sent to the ophthalmology departments of hospitals throughout Germany, 10 patients with ligneous conjunctivitis or pseudomembranous disease, ranging in age from 1 to 71 years were identified. All 10 patients had severely reduced plasminogen levels. Genetic analysis revealed homozygous type I plasminogen deficiency (which had not previously been described in humans) in 7 patients and compound heterozygous plasminogen deficiency in 1 patient. Clear differentiation was not possible in 2 patients. Most of the parents had heterozygous plasminogen deficiency. None of the patients had experienced any episodes of thrombosis. Additionally, the following observations were made: 1) Levels of polymorphonuclear (PMN)-elastase protein were markedly elevated in 6 of 6 patients and 10 of 11 parents tested, and levels were higher in homozygotes than in heterozygotes. 2) Hereditary factor XII deficiency was found in 3 of 6 patients tested. 3) C1-inhibitor was elevated in 2 of 4 patients, prekallikrein was elevated in 1 of 4 patients, and plasminogen activator inhibitor type 1 was elevated in 1 of 4 patients. Infusions of lys-plasminogen concentrate induced pronounced fibrinolytic activity as indicated by high levels of D-dimer, increases in plasmin-antiplasmin complex and decreases in polymorphonuclear elastase. C1-inhibitor, prekallikrein and PAI-1 normalized after repeated infusions of lys-plasminogen. In contrast to dysplasminogenemia, severe type I plasminogen deficiency might be seen as a problem of extravascular space, in particular of the mucous membranes, possibly triggered by mechanically induced or inflammatory lesions of the vessels supplying the tissue

SC5b-9 is the most sensitive marker in assessing disease activity in Brazilian SLE patients.

This study investigated whether increased plasma levels of terminal complement complex (SC5b-9) or split products correlate with disease activity and clinical manifestations in Brazilian systemic lupus erythematosus (SLE) patients. Comparisons with conventional measurements of complement and other inflammatory markers were also performed. Plasma levels of SC5b-9, C3a desArg, C1rs-C1Inhibitor, C3b(Bb)P, C3, C4, erythrocyte sedimentation rate (ESR) and mucoproteins (MP) were measured in 41 patients with SLE of different disease activity: 10 patients with none, 15 patients with mild, and 16 patients with moderate or severe activity. All parameters, with the exception of C3 and C3b(Bb)P, showed a statistically significant correlation with disease activity. Plasma levels of SC5b-9, C3a desArg, C4, CH50, ESR and MP revealed significant differences between the groups of patients without activity and those with moderate or severe disease. Although none of the variables were able to discriminate between patients without and those with mild activity, SC5b-9, C3a desArg, C4, ESR and mucoproteins showed significant differences between the patients with mild and those with moderate or severe disease. Among all the variables, SC5b-9 levels showed the most significant results and correlated well with the severity of the disease (p < 0.0005). Our data suggest that elevated levels of complement activation products, particularly of SC5b-9 are more sensitive markers in assessing disease activity than conventional laboratory diagnosis. Modern complement diagnosis is therefore recommended for monitoring disease progress in SLE patients.