BACKGROUND Tobacco smokers have lower serum levels of IgG than non-smokers. IgG subclass deficiency is common in patients with recurrent respiratory infections. Recurrent bronchial infections are common in smokers with chronic bronchitis (CB). We have investigated whether susceptibility to recurrent exacerbations in smokers with CB is associated with altered IgG subclass levels or IgG subclass ...

In normal adults, IgG constitutes approximately 75% of the total serum immunoglobulins. Within the IgG class, the usual order of concentration of the 4 subclasses is IgG1> IgG2> IgG3> IgG4, but the actual concentration of each may vary markedly between individuals. The four IgG subclasses show considerable differences in their properties, including ability to fix complement, to bind to macropha...

As a defective anti-polysaccharide response can exist in the absence of an immunoglobulin deficiency, a series of 26 patients with bronchiectasis of unknown aetiology was vaccinated with a 23-valent pneumococcal polysaccharide vaccine. All patients suffered from recurrent respiratory tract infections. When measuring total antibody levels to pneumococcal serotypes 3, 4 and 9, a normal polysaccha...

OBJECTIVE To evaluate epidemiological, clinical and laboratorial aspects of patients with Down syndrome, who present recurrent and/or severe infections, as well as to evaluate the presence of immunodeficiency in this population. METHODS Patients with Down syndrome diagnosed by chromosome analysis with recurrent and/or severe infections, followed at the Allergy and Immunology Unit of Children'...

Children with frequent recurrent episodes of otitis media may have a deficient IgG2 antibody response to polysaccharide antigens. Five otitis-prone children were vaccinated with heptavalent pneumococcal conjugate vaccine. While all had an IgG1 antibody response to all pneumococcal serotypes included in the conjugate vaccine, the IgG2 response, especially to serotypes 6B, 9V, 19F, and 23F, was p...

mannose-binding lectin (mbl) is a protein of innate immune system that is involved in opsonization and complement activation. mbl deficiency is associated with predisposition to infectious diseases; however subnormal levels are also seen in healthy subjects. the aim of this study was to investigate the prevalence and clinical manifestation of mbl deficiency in patients with increased susceptibi...

The foetus is dependent on its mother for passive immunity involving receptor-mediated specific transport of antibodies. IgG antibody is present in highest concentration in serum and is the only antibody type that can cross the placenta efficiently, except for its IgG2 subclass. Most of the pathogenic manifestations affecting the foetus involve capsular antigens and polysaccharides of pathogens...

A normal range for IgG1, IgG2, and IgG3 subclasses has been established for children aged 6 months to 5 years using commercially available monoclonal antisera. Of particular interest were the very low concentrations of IgG2 in some healthy children, a finding which casts doubt on the importance of IgG2 deficiency reported in some patients with otherwise unexplained infections. It was not possib...

recurrent and chronic infections in children are one of the most common reasons for physicians' visits that make a diagnostic challenge to pediatricians. although the majority of referred  children  with  recurrent  infections  are  normal,  underlying causes  of  recurrent infection  such  as  atopy,  anatomical and  functional  defects,  and  primary or  secondary immunodeficiency must be con...