ALL STEM CELLS

Clinical and immunological evaluation of patients with mild IgG1 deficiency(1999)

SUMMARY
Serum IgG subclass concentrations were determined in patients visiting, the pulmonology out-patient
clinic with chronic respiratory tract problems. A total of 24 patients with a serum IgG1 concentration
< 4·9 g/l (i.e. below the reference range) and normal values for IgG2, IgM and IgA were included.
Patients with a selective IgG1 deficiency were vaccinated with a 23-valent pneumococcal polysaccharide
vaccine. There were nine patients with a poor antibody response to pneumococcal capsular
polysaccharide antigens. Responsiveness to protein antigens was intact in all patients. Patients with
pneumonia showed a significantly lower anti-polysaccharide response in the IgG2 subclass than patients
without pneumonia. Patients with recurrent sinusitis showed a significantly lower response in the IgA
isotype after vaccination with pneumococcal polysaccharide vaccine compared with non-sinusitis
patients. It can be concluded that patients with recurrent sinopulmonary infections and a mild IgG1
subclass deficiency have an impaired IgG1 anti-polysaccharide response, which can extend to decreased
IgG2 and IgA anti-polysaccharide responses.

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INTRODUCTION
Pneumococci are a leading cause of bacterial upper and lower respiratory tract infections. Laboratory investigation in patients with recurrent sinopulmonary infections may show a normal serum immunoglobulin level, but an IgG subclass deficiency can be found.

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Keywords IgG subclass deficiency recurrent sinopulmonary infections antibody response
pneumococcal polysaccharide antigens