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Copyright of Biomédica: Revista del Instituto Nacional de Salud is the property of Instituto Nacional de Salud of Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. Specific antibody deficiency is an innate error of humoral immunity characterized by normal levels of immunoglobulin isotypes, recurrent infections, and a reduced reaction to polysaccharide antigens in vaccines. Objective. To describe the clinical and immunological characteristics of patients with specific antibody deficiency attending a pediatric hospital in Bogotá between May 2021 and September 2023. Materials and methods. We reviewed the medical records of 16 patients with specific antibody deficiency. Results. The median age at diagnosis was six and a half years. Nine were male, and 7 had a history of prematurity. Eleven patients had adequate nutritional status, and 7 had standard height. The most frequent recurrent infection was pneumonia, affecting 12 patients; more than half of them experienced some associated complications. The most common phenotype was moderate, and 15 of the individuals received immunoglobulin as definitive treatment. Conclusion. Specific antibody deficiency is a frequently underdiagnosed functional alteration of the immune system. It should be suspected in patients experiencing recurrent otitis media and pneumonia or in cases complicated by septic shock, pleural effusion, or necrotizing pneumonia.

Background:Inadequate titers of pneumococcal antibody (PA) are commonly present among patients with recurrent respiratory infections. Objective:We sought to determine the effect of the degree of inadequacy in baseline PA titers on the subsequent polysaccharide vaccine response, the incidence of sinusitis, and allergic conditions. Methods:A total of 313 patients aged 6 to 70 years with symptoms of recurrent respiratory infections were classified by baseline-pPA (percentage of protective [≥1.3 µg/mL] PA serotypes/total tested serotypes) and postvaccination pPA (post-pPA): Group A (adequate baseline-pPA), Group B (inadequate baseline-pPA, adequate post-pPA, responders), and Group C (inadequate baseline-pPA, inadequate postpPA, nonresponders, specific antibody deficiency [SAD]). Immunity against Streptococcus pneumoniae was defined as adequate when the pPA was ≥70%. Each group and combined groups, Group AB (inadequate baseline-pPA), and Group BC (adequate post-pPA) were analyzed for demographics, history of sinusitis, recurrent sinusitis in the following year, allergic conditions, and association with inadequate individual serotype titers. Results:Over 80% of patients with respiratory symptoms had inadequate baseline-pPA. Baseline-pPA and SAD prevalence are inversely related (odds ratio = 2.02, 95% CI: 1.15-3.57, P = .01). Inadequate serotype 3 antibody titer is highly associated with SAD (odds ratio = 2.02, 96% CI: 1.61-5.45, P

Specific antibody deficiency against pneumococcal serotypes was detected in a patient with recurrent episodes of fever. A 21-year-old man presented with a two-month history of recurrent episodes of fever and shaking chills. He was diagnosed with recurrent episodes of pneumonia caused by Streptococcus pneumoniae serotype 19A and treated with amoxicillin. Serotype-specific antibodies were not produced against most of the serotypes, which were consistent with moderate specific antibody deficiency. After pneumococcal 13-valent conjugate vaccination and pneumococcal polysaccharide vaccination, he adequately responded to the infecting serotype with an antibody titer of 1.1 µg/mL. There were eventually no recurrent episodes of fever with pneumonia.

Specific antibody deficiency (SAD) is a common primary immunodeficiency disorder that should be considered in older children and adults with recurrent and/or severe sinopulmonary infections. The diagnosis is characterized by inadequate antibody response to polysaccharide vaccine, specifically, pneumococcal, with normal responses to protein antigens and normal levels of serum immunoglobulins as well as immunoglobulin G (IgG) subclasses. The underlying mechanism for SAD is not completely elucidated. It is understood that young children have limited polysaccharide responsiveness, which develops with increased age. Due to this phenomenon, the consensus is that there is adequate immune maturity after age 2 years, which is the earliest for the SAD diagnosis to be established. There remains a lack of consensus on thresholds for polysaccharide nonresponse, and there are several commercial laboratories that measure a range of serotypes, with the recommendation for patients to have their diagnostic evaluation with serotype testing both before vaccination and after vaccination to be conducted by the same laboratory. Once a diagnosis has been made, the management of SAD is based on the clinical severity. Clinicians may consider prophylactic antibiotics as well as immunoglobulin replacement. These patients should be closely followed up, with the possibility of discontinuation of IgG replacement after 12 to 24 months. Children are more likely to demonstrate resolution of SAD than are adolescents and adults. Patients with SAD may also progress to a more severe immunodeficiency; therefore, continued monitoring remains a crucial principle of practice in the care of patients with SAD.

Specific antibody deficiency (SAD) is a primary immunodeficiency disease characterized by normal immunoglobulins (Igs), IgA, IgM, total IgG, and IgG subclass levels, but with recurrent infection and diminished antibody responses to polysaccharide antigens following vaccination. There is a lack of consensus regarding the diagnosis and treatment of SAD, and its clinical significance is not well understood. Here, we discuss current evidence and challenges regarding the diagnosis and treatment of SAD. SAD is normally diagnosed by determining protective titers in response to the 23-valent pneumococcal polysaccharide vaccine. However, the definition of an adequate response to immunization remains controversial, including the magnitude of response and number of pneumococcal serotypes needed to determine a normal response. Confounding these issues, anti-polysaccharide antibody responses are age- and probably serotype dependent. Therapeutic strategies and options for patients with SAD are often based on clinical experience due to the lack of focused studies and absence of a robust case definition. The mainstay of therapy for patients with SAD is antibiotic prophylaxis. However, there is no consensus regarding the frequency and severity of infections warranting antibiotic prophylaxis and no standardized regimens and no studies of efficacy. Published expert guidelines and opinions have recommended IgG therapy, which are supported by observations from retrospective studies, although definitive data are lacking. In summary, there is currently a lack of evidence regarding the efficacy of therapeutic strategies for patients with SAD. We believe that it is best to approach each patient as an individual and progress through diagnostic and therapeutic interventions together with existing practice guidelines.

Background: Specific antibody deficiency is a primary immunodeficiency characterized by normal immunoglobulins with an inadequate response to polysaccharide antigen vaccination. This disease can result in recurrent infections, the most common being sinopulmonary infections. Treatment options include clinical observation, prophylactic antibiotic therapy, and immunoglobulin supplementation therapy, each with limited clinical data about their efficacy. Objective: This study aimed to identify whether there was a statistically significant difference in the rate of infections for patients who were managed with clinical observation, prophylactic antibiotics, or immunoglobulin supplementation therapy. Methods: A retrospective chart review was conducted. Patients were eligible for the study if they had normal immunoglobulin levels, an inadequate antibody response to polysaccharide antigen-based vaccination, and no other known causes of immunodeficiency. Results: A total of 26 patients with specific antibody deficiency were identified. Eleven patients were managed with immunoglobulin supplementation, ten with clinical observation, and five with prophylactic antibiotic therapy. The frequency of antibiotic prescriptions was assessed for the first year after intervention. A statistically significant rate of decreased antibiotic prescriptions after intervention was found for patients treated with immunoglobulin supplementation (n = 11; p=0.0004) and for patients on prophylactic antibiotics (n = 5; p = 0.01). There was no statistical difference in antibiotic prescriptions for those patients treated with immunoglobulin supplementation versus prophylactic antibiotics (p = 0.21). Conclusion: Prophylactic antibiotics seemed to be equally effective as immunoglobin supplementation therapy for the treatment of specific antibody deficiency. Further studies are needed in this area. [ABSTRACT FROM AUTHOR]

Background Specific antibody deficiency (SAD) is highly associated with chronic rhinosinusitis (CRS) and is defined by inadequate post-vaccination percentage of protective (≥1.3 ug/mL) pneumococcal antibody serotypes divided by total tested serotypes (post-pPA). Objective Although

Background Inadequate titers of pneumococcal antibody (PA) are commonly present among patients with recurrent respiratory infections. Objective We sought to determine the effect of the degree of inadequacy in baseline PA titers on the subsequent polysaccharide vaccine response, the incidence of sinusitis, and allergic conditions. Methods A total of 313 patients aged 6 to 70 years with symptoms of recurrent respiratory infections were classified by baseline-pPA (percentage of protective [≥1.3 µg/mL] PA serotypes/total tested serotypes) and postvaccination pPA (post-pPA): Group A (adequate baseline-pPA), Group B (inadequate baseline-pPA, adequate post-pPA, responders), and Group C (inadequate baseline-pPA, inadequate postpPA, nonresponders, specific antibody deficiency [SAD]). Immunity against Streptococcus pneumoniae was defined as adequate when the pPA was ≥70%. Each group and combined groups, Group AB (inadequate baseline-pPA), and Group BC (adequate post-pPA) were analyzed for demographics, history of sinusitis, recurrent sinusitis in the following year, allergic conditions, and association with inadequate individual serotype titers. Results Over 80% of patients with respiratory symptoms had inadequate baseline-pPA. Baseline-pPA and SAD prevalence are inversely related (odds ratio = 2.02, 95% CI: 1.15–3.57, P = .01). Inadequate serotype 3 antibody titer is highly associated with SAD (odds ratio = 2.02, 96% CI: 1.61–5.45, P

Purpose: Specific antibody deficiency (SAD) involves a deficient response to a polysaccharide vaccine despite having normal immunoglobulin levels. The failure of the polysaccharide response can be observed as a component of various primary antibody deficiencies. However, only a few studies have described the clinical and immunological profiles in SAD and/or other primary immunodeficiencies (PIDs) in adults., Methods: A total of 47 patients who had a clinical history suggestive of antibody deficiency or had already been diagnosed with various antibody deficiencies were enrolled. Polysaccharide responses to 7 pneumococcal serotypes (4, 6B, 9V, 14, 18C, 19F and 23F) were measured using the World Health Organization enzyme-linked immunosorbent assay (WHO-ELISA), and postvaccination immunoglobulin G (IgG) titers were compared to clinical and laboratory parameters., Results: Based on the American Academy of Allergy, Asthma, and Immunology (AAAAI) criteria for the WHO-ELISA, 11 (23.4%) patients were diagnosed as having SAD. Sixteen-three percent of them had combined with other types of PID, such as IgG subclass deficiency and hypogammaglobulinemia. Postvaccination IgG titers for the serotypes 4/9V/18C correlated with IgG2 ( P = 0.012, P = 0.001, and P = 0.004) and for 6B/9V/14 with IgG3 ( P = 0.003, P = 0.041, and P = 0.036, respectively). The IgG3 subclass levels negatively correlated with forced expiratory volume in 1 second (FEV1, %) and FEV1/forced vital capacity ( P < 0.001 and P = 0.001, respectively)., Conclusion: SAD can be diagnosed in patients with normal IgG levels as well as in those deficient in IgG or the IgG3 subclass, implicating that restricted responses to Streptococcus pneumoniae polysaccharide antigens commonly exist in patients with predominantly antibody deficiency., Competing Interests: There are no financial or other issues that might lead to conflict of interest., (Copyright © 2021 The Korean Academy of Asthma, Allergy and Clinical Immunology · The Korean Academy of Pediatric Allergy and Respiratory Disease.)

Specific antibody deficiency lias been recognized as an immunodeficiency. In order to investigate an antipolysaccliaride antibody defect as a cause of rcccttrent infections, 30 children were studied. Patients who had been identified to have a major immunodeficiency or structural abnormality or a disease known to cause infection were excluded."nTliirty patints, aged I to 13.8 years (mean age, 5.8; male; female, 13:17) were chosen; all liad normal IgG and IgGl. Tiic level of IgA, IgG2 and lgG3 were of lower than normal in some cases. All were immunized with Hih conjugate (PRI'-T) vaccine, and 26 with pneumococcal vaccine. Antibody responses were measured 4-6 weeks later. Twelve showed a poor response to immunization: 8 to pneumovax 3 to Hib and 1 to both. No correlation was observed between IgG 2 level anil specific antibody responses to polysacciiaridc antigens. Tlie infections were more severe and more frequent in children who responded poorly to polysacciiaridc antigens. Chikircn who had infections in more than one site were most likely to have deficient antibody responses."nThese results show that assessment of specific antibody responses to challenge immunization is an essential part of the investigation of children suffering from recurrent pyogenic infections. The study confirms that measurement of immunoglobulin isotypes and IgG subclasses atone docs not exclude significant hormonal immune deficiency.