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The relationship between hypervariable regions, antigen-binding specificity and the three-dimensional structure of
Annales D'Immunologie
|June 1, 1976
Summary
Antibody V domains raised against pneumococcal polysaccharide show significant sequence diversity, challenging simple structure-function correlations. This suggests complex immune responses and stable germline gene transmission across species.
Area of Science:
- Immunology
- Molecular Biology
- Structural Biology
Background:
- Antibodies are crucial for adaptive immunity, recognizing specific antigens.
- The variable (V) domains of antibodies contain hypervariable regions that determine antigen-binding specificity.
- Understanding the relationship between antibody V domain sequence and antigen specificity is key to immune response studies.
Purpose of the Study:
- To analyze the amino acid sequences of V domains from three antibodies raised against type III pneumococcal polysaccharide.
- To investigate the correlation between antibody V domain primary structure and antigen-binding specificity.
- To explore the implications for germline gene usage and evolutionary conservation of antibody genes.
Main Methods:
- Amino acid sequencing of V domains (VL + VH regions) from three rabbit anti-pneumococcal antibodies.
- Comparative sequence analysis of hypervariable segments within the V domains.
- Comparison with known antibody sequences from different species and antigen specificities.
Main Results:
- Significant sequence variability was observed in the hypervariable segments of the rabbit antibody V domains, with differing lengths in the H chain's third hypervariable region.
- The observed sequence diversity does not support a simple correlation between hypervariable region primary structure and antigen-binding specificity for these antibodies.
- Structural uniformity in heavy chains with phosphorylcholine activity from mouse and human sources contrasts with the rabbit antibody diversity, suggesting stable gene transmission.
Conclusions:
- The complex immune response to a simple polysaccharide antigen involves diverse antibody V domain sequences, likely reflecting different germline gene origins.
- The findings challenge a direct, simple correlation between hypervariable region sequence and antigen specificity in this context.
- Evidence supports the stable transmission of variable region genes throughout evolution, as indicated by conserved heavy chain structures across species.