The impaired synthesis of antigen-specific antibodies, which is indispensable for an adaptive immune response to infections, is a fundamental pathomechanism that leads to clinical manifestations in children with antibody production defects. The aim of this study was to evaluate the synthesis of antigen-specific antibodies following immunization in relation to peripheral blood B cell subsets in young children with hypogammaglobulinemia. Twenty-two children, aged from 8 to 61 months, with a deficiency in one or more major immunoglobulin classes participated in the study. Postvaccination antibodies against tetanus and diphtheria toxoids, the surface antigen of the hepatitis B virus, and the capsular Haemophilus influenzae type b polysaccharide antigen were assessed along with an immunophenotypic evaluation of peripheral blood B lymph cell maturation. A deficiency of antibodies against the tetanus toxoid was assessed in 73% of cases and that against the diphtheria toxoid was assessed in 68% of cases, whereas a deficiency of antibodies against the surface antigen of the hepatitis B virus was revealed in 59% of the children included in the study. A defective response to immunization with a conjugate vaccine with the Haemophilus influenzae type b polysaccharide antigen was demonstrated in 55% of hypogammaglobulinemic patients. Increased proportions of transitional B lymph cells and an accumulation of plasmablasts accompanied antibody deficiencies. The defective response to vaccine protein and polysaccharide antigens is a predominating disorder of humoral immunity in children with hypogammaglobulinemia and may result from a dysfunctional state of the cellular elements of the immune system. A ntibody production defects are the most common category of pediatric primary immunodeficiencies (PIDs) (1, 2). The hallmark of these immunodeficiency conditions is the defective production of antigen-specific antibodies that are an indispensable element of the adaptive immune response to pathogens (3, 4). While the poor response to vaccines is another feature of humoral PIDs, the ability to synthesize postvaccination antibodies against toxoids and polysaccharides is the most specific expression of the immune response to antigens. In the evaluation of the immune response associated with antibody production, the response to vaccination against hepatitis B is not routinely recommended because of the large proportion of adults, up to between 1% and 3% of vaccinated individuals, who do not effectively synthesize antibodies against hepatitis B virus surface antigen (HBs). In infants and children, the efficiency of recombinant vaccines against hepatitis B, assessed on the basis of postvaccination anti-HBs antibody concentration over 10 mIU/ml, is estimated at 85% to 100% (5, 6). The minimal protective level of neutralizing antibodies against diphtheria and tetanus toxoids has been estimated at 0.01 to 0.1 IU/ml, whereas to achieve long-term immunity, a concentration of specific antibodies, up to 1.0 IU/ml, may be required. The synthesis of...

No abstract

Background Granulomatous lymphocytic interstitial lung disease (GLILD) has been increasingly recognized in children affected with primary immunodeficiencies (PIDs). In this study, we aimed to better characterize the spectrum of pediatric PIDs coexisting with GLILD including clinical and immunological predictors, thoracic imaging findings, and histopathologic features. Methods We respectively reviewed records of six representative cases of children, three of them affected with common variable immunodeficiency (CVID) and three with syndromic immunodeficiencies, in whom a diagnosis of GLILD was established based on clinical, radiological, and histopathologic findings. Clinical and immunological predictors for GLILD were also analyzed in the patients studied. Results All the children with GLILD had a history of autoimmune phenomena, organ-specific immunopathology, and immune dysregulation. Defective B-cell maturation and deficiency of memory B cells were found in all the children with GLILD. The radiological and histopathological features consistent with the diagnosis of GLILD, granulomatous disease, and lymphoid hyperplasia, were accompanied by chronic airway disease with bronchiectasis in children with CVID and syndromic PIDs. Conclusions Our study shows that both CVID and syndromic PIDs may be complicated with GLILD. Further studies are required to understand the predictive value of coexisting autoimmunity and immune dysregulation in the recognition of GLILD in children with PIDs.

Severe combined immunodeficiency (SCID) is characterized by the absence of functional T lymphocytes and impairment of adaptive immunity. While heterogeneity of the genetic background in SCID leads to the variability of immune phenotypes, most of affected newborns appear healthy but within the first few months they develop life-threatening opportunistic respiratory or gastrointestinal tract infections. The objective of the study was to define the presenting features and etiology of infections in children with SCID. We retrospectively reviewed five children in whom the diagnosis of SCID had been established in our pediatric immunology clinic over the last 10-year period. A viral respiratory tract infection was the first manifestation of SCID in all the children studied. Cytomegalovirus (CMV) pneumonia was recognized in as many as 4 cases and coronavirus pulmonary infection was diagnosed in one case, whereas Pneumocystis jiroveci was identified as a co-pathogen in one CMV-infected patient. Severe combined immunodeficiency is a pediatric emergency condition and given the significant impact of pulmonary CMV infection in SCID children, establishing an accurate etiological diagnosis is of essential importance in instituting the specific treatment and improving the outcome.

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by neurodegeneration, combined immunodeficiency, and oculocutaneous telangiectasia. The hyper-IgM phenotype of AT , correlating with a class-switch recombination defect, IgG and IgA deficiency, T helper and B cell lymphopenia, immune dysregulation, proinflammatory immune response, autoimmune disease, and a high risk of lymphomagenesis. Progressive liver disease is a hallmark of classical AT with the hyper-IgM phenotype and manifests as non-alcoholic hepatic steatosis and fibrosis. We report a case of a 17-year-old male AT patient, in whom a progressive granulomatous liver disease with portal hypertension, has led to massive splenomegaly and hypersplenism, metabolic liver insufficiency, bleeding from esophageal varices and pancytopenia. In this patient, an unusual severe disease course with a highly variable constellation of AT symptomatology includes granulomatous skin, visceral, and internal organs disease with liver involvement. The liver disease is associated with the hyper-IgM immunophenotype and escalating neurodegeneration, creating a vicious circle of immune deficiency, permanent systemic inflammatory response, and organ-specific immunopathology.