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Conformation of Immunoglobulin M. III. Structural requirements of antigen for complement fixation by equine IgM.
Abstract: Complexes of IgM equine anti-dansyl antibodies and different dansyl substituted carriers were tested for their ability to fix complement (C). Only dansyl92-Ficoll and dansyl12-poly-L-lysine were found to be effective. Dansyl13-bovine serum albumin, dansyl127-keyhole limpet hemocyanin, and reduced and alkylated dansyl10-ribonuclease were all ineffective. Lack of C fixation by the dansyl-ribonuclease was not due to lack of antibody-antigen complex formation, since binding at the concentrations employed for C fixation was established. However, in contrast, polymerized dansyl-ribonuclease (polydisperse, with m.w. = 74,000 to 230,000) was very effective in inducing C fixation. These results suggest that large antigen size is necessary for IgM to bind in a multivalent fashion to provide the correct conformation for C fixation. A similar conclusion had been made in earlier studies on rabbit IgM by Cunniff and Stollar. Since optimal C fixation occurred at lower antigen concentrations than maximal precipitation, it would appear that complexes in which several combining sites within a given IgM molecule may be bound to the same antigenic surface may be the most effective. The observation that the amount of C1q bound to antibody was the same in the presence and absence of antigen suggests that enhanced C fixation by antibody-antigen complexes is due to additional C component interactions such as C1r or C1s.
Publication Date: 1980-11-01 PubMed ID: 7430617 The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research explores the structural requirements of antigens for complement fixation by equine Immunoglobulin M (IgM). The study concludes that large antigen size is necessary for IgM to bind in a multivalent manner, thereby providing the correct conformation for complement fixation.
Experimental Process
The study involved testing complexes of IgM equine anti-dansyl antibodies and varying dansyl substituted carriers for their capability to fix complement (a protein-chain responsible for immune response). Unique carrier types such as:
- dansyl92-Ficoll
- dansyl12-poly-L-lysine
showed effective results. However, carriers such as:
- dansyl13-bovine serum albumin
- dansyl127-keyhole limpet hemocyanin
- reduced and alkylated dansyl10-ribonuclease
proved ineffective. Interestingly, the lack of complement fixation by the dansyl-ribonuclease was not due to a lack of antibody-antigen complex formation.
Key Observations
The research further observed that polymerized dansyl-ribonuclease (a complex with a molecular weight range from 74,000 to 230,000) was extremely effective in inducing complement fixation. This finding indicated that a large-size antigen is necessary for IgM to bind in a multifaceted way to provide the appropriate conformation for complement fixation.
Comparative Analysis
The findings from this study correlated with conclusions drawn from earlier studies on rabbit IgM by Cunniff and Stollar. Optimal complement fixation occurred at lower antigen concentrations than maximal precipitation, implying that complexes where several combining sites within a given IgM molecule might be bound to the same antigenic surface may be the most effective.
Insights from Additional Observations
The team noted that the amount of C1q (a component of the complement system) bound to the antibody remained the same in the presence and absence of antigen. This implies that enhanced complement fixation by antibody-antigen complexes is likely due to additional complement component interactions such as C1r or C1s.
Cite This Article
APA
Siegel RC, Cathou RE.
(1980).
Conformation of Immunoglobulin M. III. Structural requirements of antigen for complement fixation by equine IgM.
J Immunol, 125(5), 1910-1915.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Antigen-Antibody Complex
- Antigens
- Binding Sites, Antibody
- Complement C1 / immunology
- Complement Fixation Tests
- Dansyl Compounds / immunology
- Dansyl Compounds / pharmacology
- Horses
- Immunoglobulin M
- Polymers
- Protein Conformation
- Ribonucleases / pharmacology
Grant Funding
- AI-10115 / NIAID NIH HHS
Citations
This article has been cited 1 times.- Doekes G, Schouten J, Cats A, Daha MR. Reduction of the complement activation capacity of soluble IgG aggregates and immune complexes by IgM-rheumatoid factor. Immunology 1985 Jul;55(3):555-64.
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