Secondary hypogammaglobulinemia in adults—A large retrospective cohort study / Hipogammaglobulinemia secundaria en adultos: estudio de cohorte retrospectiva

Background and objective: IgG replacement therapy (IgG-RT) has radically changed the clinical evolution of primary immunodeficiencies, yet the information regarding secondary hypogammaglobulinemia (SHG) is insufficient or conflicting. We aim to describe clinical features, evolution and treatment of SHG patients in our center. Methods: Dynamic retrospective cohort between January 2001 and July 2021 of adults with gamma globulin fraction <0.6g/dL in a serum protein electrophoresis and a coincident decrease of IgG levels – with a disease-related SHG or treatment that reduces serum immunoglobulins. Results: We included 1012 patients with SHG with a median follow-up of 5 years (IQR 2–8). Hematological diseases were identified in 95% of the patients and 61% received drugs related to SHG. Sixty five percent had more than one etiological factor associated with SHG. Infectious diseases were present in 69% of the patients, 48% had respiratory infections and 17% had severe infections. There was statistical association between respiratory and severe infections with multiple myeloma (MM), lymphoma and rituximab. MGUS had less infections and death compared with other etiologies. IgG-RT was indicated in 18.7% of the patients and 4.6% received it for more than 6 months with variable intervals. Among the latter group, there was a significant reduction of all-type infections and respiratory infections with IgG-RT (p<0.001), and it was consistent with similar findings in lymphoma, MM and all IgG levels subgroups. Conclusion: SHG was associated with more than one etiological factor and a high frequency of infections. IgG-RT indication was irregular yet still effective. It is relevant to consider IgG levels screening, monitoring and accurate indication of IgG-RT.(AU)

Antecedentes y objetivos: La IgG sustitutiva ha cambiado radicalmente la evolución de las inmunodeficiencias primarias, mientras que la información sobre hipogammaglobulinemia secundaria (HGS) es insuficiente y discordante. El objetivo del estudio es describir las características clínicas, evolución y tratamiento de pacientes con HGS. Métodos: Cohorte retrospectiva dinámica entre enero de 2001 y julio de 2021 de adultos con proteinograma y fracción de gammaglobulina <0,6g/dL y dosaje disminuido de IgG, con enfermedad o tratamiento que produzcan HGS. Resultados: Se incluyó a 1.012 pacientes con HGS con una mediana de seguimiento de 5 años (IIC 2-8). El 95% tenía enfermedad hematológica y el 61% recibió fármacos asociados a HGS. El 65% tenía más de un factor etiológico asociado con HGS. El 69% presentó infecciones de cualquier tipo, el 48% infecciones respiratorias y el 17%, infecciones graves. Hubo asociación significativa entre infecciones respiratorias y graves entre los subgrupos de mieloma múltiple, linfoma y rituximab. Los pacientes con MGUS tuvieron menor frecuencia de infecciones y muerte comparados con otros factores etiológicos. El 18,7% de los pacientes recibió IgG sustitutiva y el 4,6% de forma crónica, con intervalos variables. Los últimos tuvieron disminución significativa de infecciones de cualquier tipo e infecciones respiratorias con IgG sustitutiva (p<0,001), que se mantuvo en los subgrupos con mieloma múltiple, linfoma y todos los niveles de IgG. Conclusión: La HGS asoció más de un factor etiológico y alta frecuencia de infecciones. La indicación de IgG sustitutiva fue irregular, pero, aún así, efectiva. Se plantea considerar el dosaje de inmunoglobulinas, monitoreo y la adecuada indicación de IgG sustitutiva.(AU)

First report of Wilson disease and Bruton agammaglobulinemia in the same patient caused by new mutations in ATP7B and BTK genes

Introduction: Wilson disease is characterized by an alteration in copper metabolism that causes its accumulation in different tissues. Its diagnosis is established by the combination of clinical manifestations and paraclinical and genetic studies. Bruton agammaglobulinemia is an X-linked recessive hereditary disease belonging to the group of primary immunodeficiencies and is produced by mutation in the Bruton tyrosine kinase (BTK) gene. Case report: A 14-year-old Colombian patient with clinical characteristics of Bruton agammaglobulinemia presented with liver disease and clinically and molecularly diagnosed with Wilson disease. Discussion: Bruton agammaglobulinemia and Wilson disease are considered rare diseases because of their low prevalence. We report for the first time a pediatric patient from southwestern Colombia presenting with both entities, and diagnosed clinically and molecularly, an association so far not reported in the literature (AU)

Uso de remdesivir en ciclos repetidos y terapia de mantenimiento con emtricitabina/tenofovir contra SARS-CoV-2 persistente en paciente inmunocomprometido / Use of repeated courses of remdesivir and maintenance treatment with emtricitabine/tenofovir against persistent SARS-CoV-2 in immunocompromised patient

El estado inmunitario del organismo es determinante en la evolución de la infección producida por el virus SARS-CoV-2. La inmunosupresión constituye uno de los factores de riesgo que incrementa la reactivación del virus en el organismo, sumado al propio estado de salud del hospedador y factores virológicos como la carga viral y el genotipo del virus (Ye et al. 2020). El Grupo de Investigación Long COVID ACTS sugiere la importante actividad de los anticuerpos en el control de la enfermedad, pues una actividad inmunitaria debilitada y ausencia de respuesta humoral parece aumentar la persistencia del virus en el organismo, con la consecuente subsistencia de la sintomatología dando lugar a una situación de COVID persistente o long COVID, término que se define como “la persistencia o desarrollo de síntomas más allá de las 4 semanas desde el inicio de la enfermedad” (Naeije & Caravita, 2021). El COVID persistente surge con mayor frecuencia en pacientes de edad avanzada, con una o más comorbilidades y un estado inmunitario comprometido. Presentamos un caso de un varón de 72 años diagnosticado de leucemia linfocítica crónica en tratamiento quimioterápico, que dio positivo en la prueba de Reacción en Cadena de la Polimerasa (PCR) con un umbral de ciclos (CT) menor a 20 durante más de 90 días y una sintomatología severa. El caso fue valorado por un equipo multidisciplinar. Se planteó la utilidad de tratamientos como el uso de ciclos repetidos de remdesivir seguido de tratamiento mantenido con emtricitabina/tenofovir disoproxilo. (AU)

The body’s immune system status is decisive in the evolution of the infection caused by the SARS-CoV-2 virus. Immunosuppression along with host health status and virologic factors such as viral load and variant genotype are risk factors that increase the possibility of viral reactivation (Ye et al. 2020). The group Long COVID ACTS suggests the important activity of antibodies to control the disease. A weakened immune system and lack of humoral response appear to increase the persistence of the virus in the body and the consequent persistence of symptoms leading to a persistent or long COVID situation, which is defined as “the persistence or development of symptoms beyond 4 weeks from the onset of the disease” (Naeije & Caravita, 2021). Persistent COVID is more frequent in elderly patients, with comorbidities and immunocompromised status. We present a case of a 72-year-old man diagnosed with chronic lymphocytic leukemia under chemotherapy treatment. COVID-19 polymerase chain reaction (PCR) testing was positive with cycle threshold (CT) values <20 for more than 90 days and severe symptoms. The case was evaluated by a multidisciplinary team. Repeated courses of remdesivir and maintenance treatment with emtricitabine/tenofovir disoproxil fumarate were applied. (AU)

Acute recurrent autoinflammatory myopericarditis: from pathophysiology to practice / Miopericarditis autoinflamatoria aguda recurrente: de la fisiopatología a la clínica

Recurrent myopericarditis is the acute inflammation of the pericardium and myocardium that relapses after a symptom-free interval of 4 to 6 weeks. A thorough differential diagnosis is necessary to identify uncommon causes that may have therapeutic and prognostic importance. These include autoinflammatory diseases, which can present as recurrent myopericarditis in genetically predisposed or impaired-immunity individuals.We present a 33-year-old male with polyclonal hypogammaglobulinemia and six episodes of myopericarditis, in which the diagnosis of a probable autoinflammatory syndrome was established. Targeted treatment based on the pathophysiological mechanismswas started with immunoglobulins and anakinra, with favourable clinical and serological outcome with no relapses.Organ-specific autoinflammatory diseases with myocardial involvement may be associated with life-threatening complications. The role of multidisciplinary care and a diagnostic approach focused on the pathophysiology of the disease could be the most important thing for early treatment to improve the prognosis and quality of life of our patients. (AU)

La miopericarditis recurrente es la inflamación aguda del pericardio yel miocardio que recidiva tras un periodo libre de síntomas de 4 a 6semanas. Es necesario realizar un diagnóstico diferencial exhaustivopara identificar causas poco comunes que puedan tener importanciaterapéutica y pronóstica. Entre ellas se encuentran las enfermedadesautoinflamatorias, que pueden presentarse como miopericarditis recurrente en individuos genéticamente predispuestos o una inmunidadalterada.Presentamos el caso de un varón de 33 años con hipogammaglobulinemia policlonal y seis episodios de miopericarditis, en el que seestableció el diagnóstico de un probable síndrome autoinflamatorio.Se inició un tratamiento dirigido con inmunoglobulinas y anakinra basado en los mecanismos fisiopatológicos de la enfermedad, con unresultado clínico y serológico favorable en ausencia de recaídas.Las enfermedades autoinflamatorias con afectación cardíaca órgano-específica pueden asociarse a complicaciones potencialmentemortales. El papel de la atención multidisciplinar y un enfoque diagnóstico centrado en la fisiopatología de la enfermedad, resultan devital importancia para instaurar un tratamiento precoz que mejore elpronóstico y la calidad de vida de nuestros pacientes. (AU)

Importancia de la determinación de actividad enzimática en el diagnóstico del déficit de adenosina desaminasa 2 (DADA2) / Importance of the determination of enzymatic activity in the diagnosis of deficiency of adenosine deaminase 2 (DADA2)

Objetivo: Describir la utilidad de la determinación de la actividad enzimática de adenosina desaminasa 2 (ADA2) en los pacientes con sospecha de déficit de ADA2 (DADA2).MétodoEstudio retrospectivo multicéntrico con análisis de los datos clínicos, bioquímicos y genéticos de los pacientes a los que se ha determinado la actividad enzimática de ADA2 mediante método espectrofotométrico.ResultadoEn tres de los 20 pacientes se confirmó el diagnóstico de DADA2 mediante la combinación de actividad enzimática reducida y variantes patogénicas bialélicas en el gen CECR1. En dos pacientes portadores de variantes de significado incierto en CECR1, el estudio de actividad enzimática permitió descartar la enfermedad.ConclusionesLa actividad enzimática reducida de ADA2 confirma el diagnóstico de DADA2, de especial importancia en los portadores de variantes de significado incierto en CECR1. (AU)

Objective: To describe the usefulness of determining the enzymatic activity of adenosine deaminase 2 (ADA2) in patients with suspected ADA2 deficiency (DADA2).MethodRetrospective multicenter study. Review with analysis of the clinical, biochemical and genetic data of the patients in whom the enzymatic activity of ADA2 has been determined by spectrophotometric method.ResultIn 3 of the 20 patients, the diagnosis of DADA2 was confirmed by the combination of reduced enzyme activity and biallelic pathogenic variants in the CECR1 gene. In 2 patients with variants of uncertain significance in CECR1, the study of enzymatic activity allowed to rule out the disease.ConclusionsThe reduced enzymatic detection of ADA2 confirms the diagnosis of DADA2, particularly important in carriers of variants of uncertain significance in CECR1. (AU)

Hipogammaglobulinemia crónica postrasplante de precursores hematopoyéticos y su tratamiento con gammaglobulina subcutánea en pacientes pediátricos / Chronic hypogammaglobulinemia after allogeneic stem cell transplantation and their treatment with subcutanaeos inmunoglobulin in pediatric patients

Introducción: La hipogammaglobulinemia en los primeros meses postrasplante de progenitores hematopoyéticos (TPH) es común en pacientes pediátricos. Durante esta fase se debe administrar tratamiento sustitutivo con inmunoglobulina humana por vía parenteral para la prevención de infecciones. En algunos casos, esta hipogammaglobulinemia persiste en el tiempo, lo que obliga a prolongar el tratamiento cuando el paciente ya no suele ser portador de una vía central, por lo que son candidatos ideales para el tratamiento de reemplazo por vía subcutánea. Existe escasa bibliografía publicada que describa el uso de esta vía en pacientes pediátricos sometidos a TPH; sin embargo, está ampliamente descrita y con muy buenos resultados en el tratamiento de reemplazo en los niños con inmunodeficiencias primarias. Pacientes y métodos: Se realiza un estudio observacional, descriptivo y longitudinal de carácter retrospectivo. Durante los años 2008-2019 se evalúan a todos los pacientes pediátricos sometidos a TPH en nuestro centro que presentan una hipogammaglobulinemia crónica persistente (superior a un año). Se evalúa la fase de tratamiento con inmunoglobulina intravenosa (Privigen®) y los primeros 4 años de tratamiento con inmunoglobulina subcutánea (Hizentra®) mediante un cuestionario. Resultados: Durante los años 2008-2019 se han realizado en nuestro centro 175 trasplantes de precursores hematopoyéticos, de los cuáles 143 (82%) superaron los 3 meses postrasplante. De estos, 3 (2%) pacientes presentaron una hipogammaglobulinemia persistente. Los 3 comparten factores descritos en la bibliografía involucrados en la reconstitución inmune. Mediante el cuestionario se observa que el cambio de gammaglobulina intravenosa a subcutánea ha supuesto una gran mejoría en la calidad de vida de los pacientes. (AU)

Introduction: Hypogammaglobulinemia in the first months after allogeneic hematopoietic stem cell transplantation (HSCT) is common in pediatric patients. During this phase, replacement therapy with human immunoglobulin must be administered parenterally to prevent infections. In some cases, this hypogammaglobulinemia persists over time, which forces further treatment when the patient is usually no longer a carrier of a central line, making them ideal candidates for subcutaneous replacement therapy. There is little published literature describing the use of this method in pediatric patients undergoing HSCT, widely described in replacement treatment in children with primary immunodeficiencies with very good results. Patients and methods: An observational, descriptive, longitudinal and retrospective study is carried out. During the years 2008–2019, we evaluated all pediatric patients undergoing HSCT in our center with persistent chronic hypogammaglobulinemia (for over a year). The treatment phase with intravenous immunoglobulin (Privigen®) and the first four years of treatment with subcutaneous immunoglobulin (Hizentra®) are evaluated using a questionnaire. Results: During the years 2008-2019, 175 patients underwent HSCT, 143 (82%) of whom exceeded three months after transplantation. 3 (2%) of them had persistent hypogammaglobulinemia. All three share factors described in the literature involved in immune reconstitution. After analyzing the questionnaire, it is observed that switching from intravenous to subcutaneous gammaglobulin has involved a great improvement in their quality of life. (AU)

Novel BTK mutation in X-linked agammaglobulinemia: Report of a 17-year-old male

Introduction and objectives: X-linked agammaglobulinemia (XLA), the first known primary immunodeficiency, is caused by rare mutations in Bruton’s tyrosine kinase (BTK) gene. Mutations in the BTK gene lead to a failure in the development and maturation of B-cell linage. A decreased number of B-cells results in agammaglobulinemia and increased susceptibility to a variety of infections. Therefore, patients with XLA usually manifest with repetitive bacterial infections, such as upper respiratory tract infections, septic arthritis, osteomyelitis, and urinary tract infections, since their infancy. Patients We report a 17-year-old Iranian boy with XLA, referred to us with a history of severe and recurrent episodes of bacterial infections for a period of six years. Results Genetic analysis using the whole Exome sequencing revealed a hemizygous missense mutation in the BTK gene (c.428 A > T, p.His143Leu). Conclusion To our knowledge, c.428 A > T has not been reported in the BTK gene (AU)

The CXCR5 T follicular helper cell compartment in children with antibody deficiencies—in search of a prognostic marker of childhood hypogammaglobulinemia

Background Novel immunodiagnostic markers are required in order to discriminate between mild hypogammaglobulinemia and severe humoral primary immune deficiencies in children. The efficacy of an antibody response to infections and vaccines is underpinned by T follicular helper (Tfh) cells, activating an immunoglobulin class switch recombination, somatic hypermutations, and affinity maturation. Objective To determine the formation of the Tfh cells in antibody deficient children and to define their importance as prognostic markers helpful in defining the severity of hypogammaglobulinemia. Methods We retrospectively reviewed medical records of 200 children aged from 2 months to 10 years, in whom hypogammaglobulinemia was assessed, from January to December 2019. In all the children studied, a flow cytometric analysis of the Tfh cell compartment was performed. Results In young infants aged from 2 to 9 months, the mean relative frequency of the Tfh population was lower than in the control population. Concomitantly, the relative values of Tfh cells, corresponding with the 95th percentile, were below the reference values in all age groups. Conclusions A deficiency of Tfh cells in young infants mirrors the immaturity of the humoral immune response, whereas in older children Tfh cells are proposed as a prognostic marker facilitating to distinguish between mild hypogammaglobulinemia and the developing common variable immunodeficiency (AU)

Common variable immunodeficiency: epidemiology, pathogenesis, clinical manifestations, diagnosis, classification, and management

Common variable immunodeficiency (CVID) is a heterogeneous disorder characterized by hypogammaglobulinemia and increased susceptibility to recurrent bacterial infections. It is the most frequent symptomatic antibody deficiency, with a wide variety of infectious and noninfectious complications. Numerous studies have demonstrated that immunological and genetic defects are involved in the pathogenesis of CVID. However, in most cases, the genetic background of the disease remains unidentified. This review aims to discuss various aspects of CVID, including epidemiology, pathogenesis, symptoms, diagnosis, classification, and management

La inmunodeficiencia variable común (CVID) es un trastorno heterogéneo caracterizado por una hipogammaglobulinemia y por una mayor susceptibilidad a infecciones bacterianas recurrentes. Se trata de la inmunodeficiencia humoral sintomática más frecuente y cursa con una extensa variedad de complicaciones infecciosas y no infecciosas. En la patogenia de la CVID están involucrados diferentes defectos inmunológicos y genéticos. Sin embargo, en la mayoría de los casos, el fondo genético de la enfermedad permanece sin identificar. Esta revisión tiene como objetivo discutir diferentes aspectos de la CVID, incluyendo epidemiología, patogenia, síntomas, diagnóstico, clasificaciones y tratamiento de la enfermedad

Linfangiectasia intestinal primaria. ¿Podría ser el propranolol una alternativa eficaz al tratamiento? / Primary intestinal lymphangiectasia: Could propranolol be an effective alternative treatment?

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Clinical and genetic profiles of patients with X-linked agammaglobulinemia from southeast Turkey: Novel mutations in BTK gene

Background: X-linked agammaglobulinemia (XLA) is characterized by absent or severely reduced B cells, low or undetectable immunoglobulin levels, and clinically by extracellular bacterial infections which mainly compromise the respiratory tract. We aimed to analyze the clinical, immunological and genetic characteristics of 22 male children with XLA. Methods: Twenty-two children with XLA from 12 unrelated families were enrolled in this study. Clinical and demographic features of patients, serum immunoglobulin levels, percentage of B cells and BTK gene mutations were reviewed retrospectively. Results: We identified 12 different mutations in 22 patients from 12 unrelated families. The most frequent type of mutation was premature stop codon (33.3%). Ten mutations had been reported previously including three missense mutations (c.1774T>C, c.1684C>T, c.83G>T), three premature stop codons (c.1558C>T, c.1573C>T, c.753G>A), two splice-site (c.683-1G>A, c.1567-12_1567-9delTTTG) and two small nucleotide deletions (c.902-904_delAAG, c.179_181delAGA). Two novel mutations of the BTK gene were also presented and included one splice-site mutation (c.391+1G>C) and one premature stop codon mutation (c.1243_1243delG). Six out of 12 mutations of the BTK gene were located in the SH1 domain, two in the PH domain, two in the SH3 domain and two in the SH2 domain. Three patients had a history of severe infection before diagnosis. We did not identify any correlation between severity of clinical symptoms and the genotype. Conclusions: Our results show that mutations in southeast Turkey could be different from those in the rest of the world and molecular genetic tests are an important tool for early confirmed diagnosis of XLA

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Recent thymic emigrants, T regulatory cells, and BAFF level in children with X-linked agammaglobulinaemia in association with chronic respiratory disease

Background: X-linked agammaglobulinaemia (XLA) is a genetic disorder affecting B cell maturation, which is characterised by a low number of B cells, agammaglobulinaemia and increased susceptibility to a variety of bacterial infections. This study was performed to assess T cell subpopulations in a group of children with XLA in association with chronic respiratory disease (CRD). Methods: Numbers of T cell subpopulations (CD3+, CD4+, CD8+, CD3+DR+, naïve, memory, recent thymic emigrants (RTE), regulatory T cells, follicular T helpers) were measured by eight-colour flow cytometry in 22 XLA patients and 50 controls. BAFF level was measured by ELISA. Results: XLA patients with CRD had a significantly lower percentage of RTE numbers and Tregs, while significantly higher absolute counts of lymphocytes, CD3+, CD8+, CD3+DR+ and CD4+CD45RO+ T cells were detected as compared with healthy controls. In patients with XLA without CRD, the number of follicular T helper cells was altered significantly (percentage and absolute), as compared with healthy controls. Additionally, they had significantly higher counts (percentage and absolute) of CD4+CD45RA+ cells and lower percentage of CD4+CD45RO+ cells in comparison with healthy controls. Conclusions: Our study affords new information concerning CRD and T cell subsets that differentiate or are maintained in the absence of B cells in children with XLA. T cell's homeostasis depends on the presence of chronic respiratory disease that may be caused by the delay in diagnosis (AU)

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Two faces of LRBA deficiency in siblings: hypogammaglobulinemia and normal immunoglobulin levels

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Primary immunodeficiency diseases in Northern Iran

INTRODUCTION: Primary immunodeficiency diseases (PID) are a heterogeneous group of inherited disorders, characterised by recurrent severe infections, autoimmunity and lymphoproliferation. Despite impressive progress in identification of novel PID, there is an unfortunate lack of awareness among physicians in identification of patients with PID, especially in non-capital cities of countries worldwide. RESULT: This study was performed in a single-centre paediatric hospital in Northern Iran during a 21-year period (1994-2015). Ninety-four patients were included in this study. The majority of cases had antibody deficiencies (37.23%), followed by well-defined syndromes with immunodeficiency in 16 (17.02%), phagocytic disorders in 15 patients (15.95%), complement deficiencies in 15 patients (15.95%), immunodeficiencies affecting cellular and humoral immunity in nine patients (9.57%), disease of immune dysregulation in three (3.19%), and defects in intrinsic and innate immunity in one (1.06%). CONCLUSION: It seems that there are major variations in frequency of different types of PID in different regions of a country. Therefore, reporting local data could provide better ideas to improve the local health care system strategists and quality of care of PID patients

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Waldmann's disease: a rare cause of protein losing enteropathy in an adult patient

Primary intestinal lymphangiectasia or Waldmann’s disease is an uncommon cause of protein losing enteropathy with an unknown etiology and is usually diagnosed during childhood. It is characterized by dilation and leakage of intestinal lymph vessels leading to hypoalbuminemia, hypogammaglobulinemia and lymphopenia. Differential diagnosis should include erosive and nonerosive gastrointestinal disorders, conditions involving mesenteric lymphatic obstruction and cardiovascular disorders that increase central venous pressure. Since there are no accurate serological or radiological available tests, enteroscopy with histopathological examination based on intestinal biopsy specimens is currently the gold standard diagnostic modality of intestinal lymphangiectasia. We report a rare case of a primary intestinal lymphangiectasia in a 60-year-old Caucasian female who presented with asymptomatic hypoalbuminemia and hypogammaglobulinemia. After the diagnosis of a protein losing enteropathy, the patient underwent an enteroscopy and biopsies were taken, whose histological examination confirmed dilated intestinal lymphatics with broadened villi of the small bowel. Secondary causes of intestinal lymphangiectasia were excluded and the diagnosis of Waldmann’s disease was recorded. The patient was put on a high-protein and low-fat diet with medium-chain triglyceride supplementation with improvement (AU)

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Prospective evaluation of Streptococcus pneumoniae serum antibodies in patients with primary immunodeficiency on regular intravenous immunoglobulin treatment

BACKGROUND: This is a prospective study that assessed pneumococcal antibody levels in PID patients under intravenous immunoglobulin (IVIG) treatment using different brands. METHODS: Twenty-one patients receiving regular IVIG every 28 days were invited to participate: 12 with common variable immunodeficiency, six with X-linked agammaglobulinaemia and three with hyper-IgM syndrome. One blood sample was collected from each patient just prior to IVIG administration at a threemonth time interval during one year. A questionnaire was filled in with patient's demographic data and history of infections during the study period. Streptococcus pneumoniae antibodies against six serotypes (1, 5, 6B, 9V, 14 and 19F) were assessed by ELISA both in patients' serum (trough levels) and in IVIG samples. RESULTS: Median total IgG trough serum levels were 7.91 g/L (range, 4.59-12.20). All patients had antibody levels above 0.35 g/mL to the six serotypes on all four measurements. However, only 28.6% of patients had pneumococcal antibodies for the six analysed serotypes above 1.3 g/mL on all four evaluations during the one-year period. No correlation was found between IgG trough levels and pneumococcal specific antibodies. Eighteen of the 21 patients (85.7%) had infections at some point during the 12-month follow-up, 62/64 (96.9%) clinically classified in respiratory tract infections, four of which were pneumonia. CONCLUSIONS: Pneumococcal antibodies are present in a high range of concentrations in sera from PID patients and also in IVIG preparations. Even maintaining a recommended IgG trough level, these patients can be susceptible to these bacteria and that may contribute to recurrent respiratory infections

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