Regulation of complement activity by immunoglobulin. I. Effect of immunoglobulin isotype on C4 uptake on antibody-sensitized sheep erythrocytes and solid phase immune complexes.


Journal Article

Intravenous Ig, composed principally of IgG, prevents complement attack by inhibiting C3 and C4 uptake onto target cells and tissues. Using two different models, Ab-sensitized SRBC and BSA-anti BSA solid phase immune complexes, we have examined the complement inhibitory capacity of three Ig classes (IgG, IgM, IgA) focussing on inhibition of C4 uptake. It was found that on both a weight and molar basis, monomeric serum IgA and IgM were far more active than IgG (weight efficiency ratios were 1.0, 20.8, and 236.3, and molar efficiency ratios 1.0, 24.0, and 1382.9 for polyclonal IgG, IgA1, and IgM, respectively). Monoclonal IgM were less active than polyclonal IgM (50% inhibition was achieved in SRBC model by 0.022, 0.30, 1.6, and 1.6 mg/ml of polyclonal IgM and monoclonal IgM from patients Lew, Will, and Pri). Secretory IgA was less active than serum IgA1 and similar in inhibitory activity to IgG (weight and molar efficiency ratios 1.5 and 0.6 compared with IgG). All tested preparations were less active in the solid phase immune complex model than in the sensitized cell model. A mixture of Igs of different isotypes was somewhat more active than any isotype alone. These results suggest that polyclonal serum IgA and IgM can also be considered for active therapy in diseases accompanied by the activation of classical complement pathway.

Full Text

Cited Authors

  • Miletic, VD; Hester, CG; Frank, MM

Published Date

  • January 15, 1996

Published In

Volume / Issue

  • 156 / 2

Start / End Page

  • 749 - 757

PubMed ID

  • 8543829

Pubmed Central ID

  • 8543829

International Standard Serial Number (ISSN)

  • 0022-1767


  • eng

Conference Location

  • United States