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Expression of properdin in complete and incomplete deficiency: normal in vitro synthesis by monocytes in two cases with properdin deficiency type II due to distinct mutations

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Author

Summary, in English

Three properdin deficiency phenotypes have been reported--complete deficiency (type I), incomplete deficiency (type II), and dysfunction of properdin protein (type III)--all associated with increased susceptibility to meningococcal disease. Expression of properdin by monocytes was examined in type I deficiency and in two unrelated cases with type II deficiency, one from a Swedish and one from a Danish family. The properdin gene in the Danish family contained a point mutation in exon 8 causing a Gln316-->Arg substitution, distinct from a point mutation in exon 4 previously found in the Swedish family. Both genes coded for physicochemically abnormal properdin molecules with changed hydrophilicity. Monocytes from all the properdin-deficient individuals produced properdin mRNA in a normal fashion. In type I deficiency no intracellular or secreted properdin was found, indicating rapid intracellular degradation. Monocytes from the males with type II deficiency expressed and secreted properdin normally. Properdin in sera with type II deficiency showed abnormal oligomerization with a relative decrease in properdin trimers and tetramers. Our findings suggest that the low concentration of circulating properdin in type II deficiency is caused by increased extracellular catabolism. Analysis of properdin expression by monocytes in a female carrier in the family with properdin deficiency type I provided direct evidence of lyonization at the cellular level.

Publishing year

1998

Language

English

Pages

272-282

Publication/Series

Journal of Clinical Immunology

Volume

18

Issue

4

Document type

Journal article

Publisher

Springer

Topic

  • Immunology in the medical area

Keywords

  • Complement
  • human
  • lyonization
  • oligomerization
  • X chromosome

Status

Published

Research group

  • Cardiovascular Research - Immunity and Atherosclerosis

ISBN/ISSN/Other

  • ISSN: 0271-9142