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Homozygosity for the IgG2 subclass allotype G2M(n) protects against severe infection in hereditary C2 deficiency

Author

Summary, in English

Homozygous C2 deficiency (C2D) is the most common deficiency of the classical complement pathway in Western countries. It is mostly found in patients with autoimmune disease or susceptibility to bacterial infections and in healthy persons. We wished to assess to what extent other immunological factors might explain differences of susceptibility to infections in C2D. For this reason, 44 Swedish patients with C2D were stratified with regard to the severity of documented infections. Investigations of IgG subclass levels, IgG subclass-specific GM allotypes, concentrations of factor B, properdin, and factor H, and polymorphisms of mannan-binding lectin and the Fe receptors Fc gamma RIIa and Fc gamma RIIIb were performed. Homozygosity for the G2M*n allele, which is known to promote Ab responses to polysaccharide Ags, was strongly associated with the absence of severe infections (P < 0.001) in the patients, suggesting a major protective role. The combination of mannan (or mannose)-binding lectin and C2 deficiency was found to be a minor susceptibility factor for invasive infection (p = 0.03). Low concentrations of IgG2 and factor B might sometimes contribute to susceptibility to infection. Other factors investigated did not appear to be important. In conclusion, the findings indicated that efficient Ab responses to polysaccharides are protective against severe infection in C2D. Implications with regard to vaccinations should be considered.

Publishing year

2006

Language

English

Pages

722-728

Publication/Series

Journal of Immunology

Volume

177

Issue

1

Document type

Journal article

Publisher

American Association of Immunologists

Topic

  • Immunology in the medical area

Status

Published

ISBN/ISSN/Other

  • ISSN: 1550-6606