Thrombin in the Activation of the Fluid Contact Phase in Patients with Hereditary Angioedema Carrying the F12 P.Thr309Lys Variant.

Hereditary angioedema due to pathogenic FXII variants (HAE-FXII) is a rare dominant disease caused by increased activation of the plasma contact system. The most prevalent HAE-FXII variant, c.1032C > A p.Thr309Lys (FXII309Lys), results in a smaller FXII protein with increased sensitivity to fluid-phase activation by poorly understood mechanisms. We aimed to investigate the functionality of the FXII309Lys variant in 33 HAE-FXII patients, 25 healthy controls and 46 patients with congenital disorders of glycosylation (CDG). Activation of the plasma contact system was assessed by western blot and amidolytic assay in basal conditions or after treatment with either artificial or physiological activators. Recombinant wild-type and FXII309Lys variants were expressed in S2 insect (Drosophila) cells. Amidolytic and fibrin generation assays were performed in fresh plasma samples. FXII309Lys samples exhibited an increased electrophoretic mobility comparable with N-glycan-deficient FXII from CDG patients and asialo-FXII generated by neuraminidase treatment. They presented increased sensitivity to activation by dextran sulphate and silica which resulted in the generation of an aberrant 37-kDa heavy chain. We did not observe increased susceptibility of FXII309Lys to proteolysis by exogenous or tPA-generated plasmin. However, both exogenous and endogenous thrombin cleaved the FXII309Lys variant, releasing a 37-kDa fragment and resulting in enhanced proteolytic activation on the fluid phase. This model supports a sequential proteolytic activation process involving thrombin priming of FXII309Lys, followed by kallikrein cleavage and generation of active ßFXIIa. The present results and the observation that angioedema episodes in HAE-FXII patients occur predominantly during hypercoagulable situations suggest a key role for thrombin.

Guía de laboratorio para el diagnóstico de pacientes con síndrome crioglobulinémico / Laboratory guidelines for the diagnosis of patients with cryoglobulinaemic syndrome

Los síndromes crioglobulinémicos comprenden un conjunto de manifestaciones que se encuentran en diversas enfermedades y que comparten un mismo mecanismo fisiopatológico: el depósito de crioglobulinas en lechos vasculares. La presencia de crioglobulinas es criterio diagnóstico de estos síndromes por lo que es imprescindible su correcta detección y caracterización. El Grupo de Inmunoquímica de la Sociedad Española de Inmunología ha realizado una revisión exhaustiva clínica y metodológica, debido a la heterogeneidad técnica interlaboratorios, con el objetivo de proporcionar una herramienta útil y efectiva para el diagnóstico de síndromes crioglobulinémicos

Cryoglobulinaemic syndromes include a collection of manifestations that are found in various diseases and that share a pathophysiological mechanism: cryoglobulin deposit in vascular beds. For these syndromes, the presence of cryoglobulins is a diagnostic criterion, and their correct detection and characterisation are therefore essential. The Immunochemistry Group of the Spanish Society of Immunology conducted a comprehensive clinical and methodological review, due to the interlaboratory heterogeneity in techniques, with the objective of providing a useful and effective tool for diagnosing cryoglobulinaemic syndromes

Serum complexes between C1INH and C1INH autoantibodies for the diagnosis of acquired angioedema.

Acquired angioedema due to C1-inhibitor (C1INH) deficiency (AAE) is caused by secondary C1INH deficiency leading to bradykinin-mediated angioedema episodes. AAE typically presents in adulthood and is associated with B cell lymphoproliferation. Anti-C1INH autoantibodies (antiC1INHAbs) are detectable in a subset of AAE cases and considered a hallmark of the disease. When free antiC1INHAbs and malignant tumors are not detectable, diagnosis relies on the finding of low C1INH levels and/or function, lack of family history and SERPING1 mutations, age at onset and low or undetectable C1q levels, none of which is specific for AAE. We tested the diagnostic value of a novel enzyme-linked immunosorbent assay (ELISA) for the detection of circulating complexes between C1INH and antiC1INHAbs (C1INH-antiC1INHAb) in the serum of 20 European AAE patients characterized on the basis of their complement levels and function. Free antiC1INHAbs were detected in nine of 20 patients [six of immunoglobulin (Ig)G class, two of IgM class and one simultaneously presenting IgG and IgM classes], whereas C1INH-antiC1INHAb complexes were found in 18 of 20 of the AAE cases, regardless of the presence or absence of detectable free anti-C1INHAbs. Of note, nine of 20 patients showed negative free antiC1INHabs, but positive C1INH-antiC1INHAb complexes in their first measurement. In the cohort presented, IgM-class C1INH-antiC1INHAb are specifically and strongly associated with low C1q serum levels. Detection of C1INH-antiC1-INHAbs provides an added value for AAE diagnosis, especially in those cases in whom no free anti-C1INH antibodies are detected. The link between IgM-class C1INH-antiC1INHAb complexes and C1q consumption could have further implications for the development of autoimmune manifestations in AAE.

Laboratory guidelines for the diagnosis of patients with cryoglobulinaemic syndrome. / Guía de laboratorio para el diagnóstico de pacientes con síndrome crioglobulinémico.

Cryoglobulinaemic syndromes include a collection of manifestations that are found in various diseases and that share a pathophysiological mechanism: cryoglobulin deposit in vascular beds. For these syndromes, the presence of cryoglobulins is a diagnostic criterion, and their correct detection and characterisation are therefore essential. The Immunochemistry Group of the Spanish Society of Immunology conducted a comprehensive clinical and methodological review, due to the interlaboratory heterogeneity in techniques, with the objective of providing a useful and effective tool for diagnosing cryoglobulinaemic syndromes.

Acquired angioedema with anti-C1-inhibitor autoantibodies during assisted reproduction techniques

No disponible

Laboratory guidelines for the diagnosis and follow-up of patients with monoclonal gammopathies.

We present guidelines from the Immunochemistry group of the Spanish Society for Immunology that are designed to provide a practical tool for the diagnosis and follow-up of monoclonal gammopathies. We review the clinical and analytical features of various monoclonal gammopathies, international consensus guidelines and techniques used to detect and follow-up monoclonal components.

Serum properdin consumption as a biomarker of C5 convertase dysregulation in C3 glomerulopathy.

Properdin (P) stabilizes the alternative pathway (AP) convertases, being the only known positive regulator of the complement system. In addition, P is a pattern recognition molecule able to initiate directly the AP on non-self surfaces. Although P deficiencies have long been known to be associated with Neisseria infections and P is often found deposited at sites of AP activation and tissue injury, the potential role of P in the pathogenesis of complement dysregulation-associated disorders has not been studied extensively. Serum P levels were measured in 49 patients with histological and clinical evidence of C3 glomerulopathy (C3G). Patients were divided into two groups according to the presence or absence of C3 nephritic factor (C3NeF), an autoantibody that stabilizes the AP C3 convertase. The presence of this autoantibody results in a significant reduction in circulating C3 (P < 0·001) and C5 levels (P < 0·05), but does not alter factor B, P and sC5b-9 levels. Interestingly, in our cohort, serum P levels were low in 17 of the 32 C3NeF-negative patients. This group exhibited significant reduction of C3 (P < 0·001) and C5 (P < 0·001) and increase of sC5b-9 (P < 0·001) plasma levels compared to the control group. Also, P consumption was correlated significantly with C3 (r = 0·798, P = 0·0001), C5 (r = 0·806, P < 0·0001), sC5b-9 (r = -0·683, P = 0·043) and a higher degree of proteinuria (r = -0·862, P = 0·013). These results illustrate further the heterogeneity among C3G patients and suggest that P serum levels could be a reliable clinical biomarker to identify patients with underlying surface AP C5 convertase dysregulation.

C1 inhibitor function using contact-phase proteases as target: evaluation of an innovative assay.

BACKGROUND: Controlling prekallikrein activation by C1 inhibitor (C1Inh) represents the most essential mechanism for angioedema patient protection. C1Inh function in the plasma is usually measured based on the residual activity of the C1s protease not involved in the pathological process. We have hereby proposed an alternative enzymatic measurement of C1Inh function based on contact-phase activation and correlation with angioedema diagnostic requirements. METHODS: The contact phase was reconstituted using the purified components, with C1Inh standard or plasma sample. The kinetics of the amidase activity were monitored using Pro-Phe-Arg-pNA, independently of alpha2-macroglobulin. We prevented any interference from a possible high plasma kininogenase activity by preincubating the samples with protease inhibitor. Receiver operating characteristics (ROC) were used to calculate the assay's diagnostic performance. RESULTS: The calibration curve was built using C1Inh standard (threshold limit 0.10 × 10(-3) U, i.e., 0.2 pmol), and C1Inh function was quantified in the sample, with a reference interval established based on healthy individuals (n = 281; men: 0.61-1.10 U/ml, median: 0.85 U/ml; women: 0.42-1.08 U/ml, median: 0.74 U/ml). The median values of female donors were lower than those of the others due to estrogen, yet C1Inh function remained within the reference interval. The ROC curve calculation provided the following optimum diagnostic cutoff values: women 0.36 U/ml (area under curve [AUC]: 0.99; sensitivity: 93.48%; specificity: 99.37%); and men 0.61 U/ml (AUC: 1; sensitivity: 100.0%; specificity: 100.0%). CONCLUSION: The performance outcome provided features suitable for angioedema diagnostic or follow-up. Established by means of the kinin formation process, this assay should be preferred over the method based on a C1s protease target.

Clinical Pattern and Acute and Long-term Management of Hereditary Angioedema Due to C1-Esterase Inhibitor Deficiency.

BACKGROUND: Hereditary angioedema due to C1-esterase inhibitor deficiency (HAE-C1-INH) is a life-threatening disease. OBJECTIVES: To describe the clinical characteristics and management of patients with HAE-C1-INH during routine clinical practice. METHODS: An observational, retrospective study was performed in patients with HAE-C1-INH. Demographic, clinical, and analytical data were collected from 2 periods: period A (October 2009-September 2010) and period B (October 2007-September 2009). RESULTS: We studied 112 patients with HAE-C1-INH (57.1% females). Age at onset of symptoms was 14.4 years (lower in patients who had experienced attacks in the previous year). In period B (n=87), 62.1% of patients presented at least 1 edema attack (median, 3.5 attacks/patient/2 years), and 19.1% of attacks were treated. In period A (n=77), 58.4% of patients were on maintenance therapy. Stanozolol was the most widely used drug (48.9%), with a mean weekly dose of 6.7 mg. At least 1 attack was recorded in 72.7% of patients (median, 3.0 attacks/patient/year), and 31.5% of the attacks were treated. Treatment of acute attacks increased by 12.4%. CONCLUSION: Age at onset of symptoms is associated with clinical expression of disease. The higher age at onset of symptoms, the fewer number of attacks per patient and year, and the lower dose of attenuated androgens necessary to control the disease than in other series lead us to hypothesize that HAE-C1-INH could have a less severe expression in Spain. Acute attacks seem to be treated increasingly often.

Clinical pattern and acute and long-term management of hereditary angioedema due to C1-esterase inhibitor deficiency

Background: Hereditary angioedema due to C1-esterase inhibitor deficiency (HAE-C1-INH) is a life-threatening disease. Objectives: To describe the clinical characteristics and management of patients with HAE-C1-INH during routine clinical practice. Methods: An observational, retrospective study was performed in patients with HAE-C1-INH. Demographic, clinical, and analytical data were collected from 2 periods: period A (October 2009-September 2010) and period B (October 2007-September 2009). Results: We studied 112 patients with HAE-C1-INH (57.1% females). Age at onset of symptoms was 14.4 years (lower in patients who had experienced attacks in the previous year). In period B (n=87), 62.1% of patients presented at least 1 edema attack (median, 3.5 attacks/patient/2 years), and 19.1% of attacks were treated. In period A (n=77), 58.4% of patients were on maintenance therapy. Stanozolol was the most widely used drug (48.9%), with a mean weekly dose of 6.7 mg. At least 1 attack was recorded in 72.7% of patients (median, 3.0 attacks/patient/year), and 31.5% of the attacks were treated. Treatment of acute attacks increased by 12.4%. Conclusion: Age at onset of symptoms is associated with clinical expression of disease. The higher age at onset of symptoms, the fewer number of attacks per patient and year, and the lower dose of attenuated androgens necessary to control the disease than in other series lead us to hypothesize that HAE-C1-INH could have a less severe expression in Spain. Acute attacks seem to be treated increasingly often (AU)

Antecedentes: El angioedema hereditario por déficit del inhibidor de la C1 esterasa (AEH-C1-INH) es potencialmente mortal. Objetivos: Describir las características clínicas y el manejo de pacientes con AEH-C1-INH durante la práctica clínica habitual. Métodos: Estudio retrospectivo observacional de pacientes con AEH-C1-INH. Se recogieron datos demográficos, clínicos y analíticos en los periodos A (Octubre 2009-Septiembre 2010) y B (Octubre 2007-Septiembre 2009). Resultados: Se estudiaron 112 pacientes con AEH-C1-INH (57,1% mujeres) con edad de inicio de los síntomas de 14,4 años (inferior en aquellos pacientes con ataques en el último año). En el periodo B (n=87) 62,1% tuvo al menos un ataque (mediana: 3,5 ataques/paciente /2 años) y el 19,9% de los ataques se trataron. En el periodo A (n=77) 58,4% recibieron tratamiento de mantenimiento, siendo el estanozolol el fármaco más utilizado (48,9%) (dosis media semanal 6,7mg). El 72,7% de los pacientes tuvo al menos un ataque (mediana: 3,0 ataques / paciente / año), el 31,5% se trataron. Hubo un incremento del 12,4% de tratamientos de ataques agudos. Conclusiones: La edad de inicio de los síntomas está relacionada con la expresión clínica de la enfermedad. La edad superior del inicio de los síntomas, el menor número de ataques por paciente/año, y una dosis inferior de andrógenos atenuados para controlar la enfermedad, comparado con otros países, permite hipotetizar que el AEH-C1-INH en España tendría una expresión clínica menos grave. Existe una tendencia al alza en la frecuencia de tratamiento de ataques agudos (AU)

Hereditary angioedema with F12 mutation: factors modifying the clinical phenotype.

BACKGROUND: Hereditary angioedema (HAE) with normal C1 inhibitor (C1Inh) associated with the c.983C>A and c.983C>G mutations of the F12 gene (FXII-HAE) is a rare condition, and presents with highly variable clinical expression. On the basis of data gathered from a large carrier cohort, we assessed the modifiers affecting the clinical phenotype. METHODS: We analyzed clinical and biological data recorded from 118 mutation carriers (80 symptomatic and 38 asymptomatic), 58 noncarrier relatives from 40 families, and 200 healthy donors. Disease severity was scored in relation to frequency and location of edema, as well as age at disease onset. To predict FXII-HAE disease severity, we analyzed the biological phenotype [C1Inh, C4, spontaneous amidase, angiotensin-I-converting enzyme (ACE), aminopeptidase P (APP), and carboxypeptidase N/M (CPN)] by means of logistic regression (Akaike information criterion) and odds ratio (OR). RESULTS: Meaningful variables contributed to FXII-HAE, with the kinin catabolism enzymes ACE and CPN exhibiting a significant inverse relationship with disease severity (OR = 0.36, 95% CI 0.23-0.59, P < 0.001; OR = 0.58, 95% CI 0.36-0.91, P < 0.05, respectively). CPN activities were 37.5 (28.5-41.3) nmol/ml/min and 38.5 (32.8-45.6) for FXII-HAE asymptomatic and symptomatic carriers, respectively, and 37.9 (30.5-43.7) nmol/ml/min for noncarriers. Angiotensin-I-converting enzyme activities were 58 (44-76) and 49 (35-59) nmol/ml/min for FXII-HAE asymptomatic and symptomatic carriers, respectively, and 56 (49-66) nmol/ml/min for noncarriers. CONCLUSIONS: The FXII-HAE is associated with modifiers, for example kinin catabolism enzymes, ACE and CPN, different from those recognized in HAE with C1Inh deficiency.

A novel method for direct measurement of complement convertases activity in human serum.

Complement convertases are enzymatic complexes that play a central role in sustaining and amplification of the complement cascade. Impairment of complement function leads directly or indirectly to pathological conditions, including higher infection rate, kidney diseases, autoimmune- or neurodegenerative diseases and ischaemia-reperfusion injury. An assay for direct measurement of activity of the convertases in patient sera is not available. Existing assays testing convertase function are based on purified complement components and, thus, convertase formation occurs under non-physiological conditions. We designed a new assay, in which C5 blocking compounds enabled separation of the complement cascade into two phases: the first ending at the stage of C5 convertases and the second ending with membrane attack complex formation. The use of rabbit erythrocytes or antibody-sensitized sheep erythrocytes as the platforms for convertase formation enabled easy readout based on measurement of haemolysis. Thus, properties of patient sera could be studied directly regarding convertase activity and membrane attack complex formation. Another advantage of this assay was the possibility to screen for host factors such as C3 nephritic factor and other anti-complement autoantibodies, or gain-of-function mutations, which prolong the half-life of complement convertases. Herein, we present proof of concept, detailed description and validation of this novel assay.

Consensus statement on the diagnosis, management, and treatment of angioedema mediated by bradykinin. Part II. Treatment, follow-up, and special situations.

BACKGROUND: There are no previous Spanish guidelines or consensus statements on bradykinin-induced angioedema. AIM: To draft a consensus statement on the management and treatment of angioedema mediated by bradykinin 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, 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 were held to reach the consensus. RESULTS: Treatment approaches are discussed, and the consensus reached is described. Specific situations are addressed, namely, pregnancy, contraception, travelling, blood donation, and organ transplantation. CONCLUSIONS: A review of and consensus on treatment of bradykinin-induced angioedema is presented.

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.

Utility of oligoclonal IgG band detection for MS diagnosis in daily clinical practice.

An early and accurate diagnosis of multiple sclerosis (MS) is very important, since it allows early treatment initiation, which reduces the activity of the disease. Oligoclonal IgG band (OCGB) detection is a good ancillary tool for MS diagnosis. However, it was argued that its usefulness was limited by the high interlaboratory variability. In the last years, different techniques for OCGB detection have appeared. We performed a blinded aleatorized multicenter study in 19 Spanish hospitals to assess the accuracy and reproducibility of OCGB detection in this new scenario. We studied cerebrospinal fluid (CSF) and serum samples from 114 neurological patients. Every hospital contributed to the study with triplicated pairs of CSF and serum samples of six patients and analyzed 18 different samples. Global analysis rendered a sensitivity of 92.1%, a specificity of 95.1% and a Kappa value of 0.81. This shows that current techniques for OCGB detection have good accuracy and a high interlaboratory reproducibility and thus, represent a good tool for MS diagnosis. When we analyzed separately the different techniques used for OCGB detection, the highest concordance was observed in western blot with alkaline phosphatase detection (kappa=0.91). This indicates that high sensitivity techniques improve the reproducibility of this assay.

C7 deficiency and meningococcal infection susceptibility in two spanish families.

In this work, we report the genetic basis of C7 deficiency in two different Spanish families. In family 1, by using exon-specific polymerase chain reaction and sequencing, a recently described mutation was found in homozygosity in the patient; a single base change in exon 15 (C2107T) leading to a stop codon that causes truncation of the C-terminal portion of C7 (Q681X). Patient's father, mother and sister were heterozygous for this mutation. Interestingly, patient's parents were not related. In family 2, a new single base mutation in exon 2 (G90A), leading to a stop codon that causes the premature truncation of C7 (W8X), was found in the patient, mother and sister 1. Additionally, patient 2, her father and sisters, displayed a missense mutation in exon 9 (G1135C) resulting in a change of aminoacid (G357R). Although sister 1 bore the same mutations in the C7 gene that patient 2, she remains asymptomatic. Because both mutations were found in the patient and her sister, we analyse other defence mechanisms such as FcgammaR polymorphisms as well as mannose-binding lectin alleles (MBL2 gene) and MBL levels. Results showed that both siblings bore identical combinations of FcgammaR allotypes and different MBL2 alleles, exhibiting patient 2 a MBL-insufficient genotype. Normal MBL levels were found in patient 1 and in two previously studied C7-deficient siblings, suggesting the involvement of other mechanisms of immunity distinct of FcgammaR variants and the MBL pathway, for the absence of meningococcal recurrent infections in certain C7-deficient individuals.

Successful renal transplantation in a patient with atypical hemolytic uremic syndrome carrying mutations in both factor I and MCP.

Kidney transplantation in patients with atypical hemolytic uremic syndrome (aHUS) carrying mutations in the soluble complement regulators factor H (CFH) or factor I (CFI) is associated with elevated risk of disease recurrence and almost certain graft loss. In contrast, recurrence is unusual in patients with mutations in the membrane-associated complement regulator membrane cofactor protein (MCP) (CD46). Therefore, a panel of experts recently recommended the combined liver-kidney transplantation to minimize aHUS recurrence in patients with mutations in CFH or CFI. There was, however, very limited information regarding transplantation in patients carrying mutations in both soluble and membrane-associated complement regulators to support a recommendation. Here, we report the case of an aHUS patient with a heterozygous mutation in both CFI and MCP who received an isolated kidney transplant expressing normal MCP levels. Critically, the patient suffered from a severe antibody-mediated rejection that was successfully treated with plasmapheresis and IvIgG. Most important, despite the complement activation in the allograft, there was no evidence of thrombotic microangiopathy, suggesting that the normal MCP levels in the grafted kidney were sufficient to prevent the aHUS recurrence. Our results suggest that isolated kidney transplantation may be a good first option for care in aHUS patients carrying CFI/MCP combined heterozygous mutations.