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Subtle sequence differences in a tumour-associated peptide epitope translate into major changes in antigenicity
Jonas Persson1, Johan Lantto, Torbjörn Drakenberg
1Department of Immunotechnology, Lund University, P.O. Box 7031, S-22007 Lund, Sweden.
Molecular Immunology
|June 14, 2005
Summary
Subtle sequence changes in tumor-associated antigen mucin-1 significantly impact antigenicity and immunodominance. Even conservative amino acid substitutions can drastically alter how the immune system recognizes cancer epitopes.
Area of Science:
- Immunology
- Biochemistry
- Oncology
Background:
- Antigenicity, the capacity to bind immune receptors, is not well-defined.
- Tumor-associated antigen mucin-1 (MUC1) is a key target in cancer research.
Purpose of the Study:
- To investigate how minor sequence variations in MUC1 peptides affect their antigenicity.
- To understand the parameters defining antigenicity and immunodominance.
Main Methods:
- Synthesized two highly related MUC1 peptides differing by a conservative substitution.
- Assessed in vitro binding of these peptides to a large repertoire of synthetic human antibody fragments.
Main Results:
- A conservative aspartate-threonine to glutamate-serine change rendered one peptide significantly less antigenic.
- This reduced antigenicity occurred despite no observable difference in peptide structure in solution.
- The less antigenic peptide selected for antibodies targeting regions outside the previously defined immunodominant epitope.
Conclusions:
- Subtle sequence alterations profoundly influence epitope antigenicity and immunodominance.
- MUC1 antigenicity is sensitive to minor sequence modifications, impacting potential immunotherapies.