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Conformation-dependent recognition of a protein by T cells requires presentation without processing
M Z Atassi1, G S Bixler, T Yokoi
1Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030.
The Biochemical Journal
|May 1, 1989
Summary
T-cell recognition of protein antigens depends on their native conformation, not just fragments. This study shows T cells recognize intact lysozyme, challenging prior assumptions about antigen processing.
Area of Science:
- Immunology
- Protein Chemistry
- Molecular Biology
Background:
- Antigen presentation to T cells is traditionally thought to involve intracellular breakdown into fragments.
- This process is assumed to make T-cell recognition independent of the protein's original conformation.
Purpose of the Study:
- To investigate whether T-cell recognition of protein antigens in vitro is conformation-dependent.
- To determine if native or processed protein fragments trigger immune recognition.
Main Methods:
- Generation of T-cell lines and clones from primed mice using native and unfolded lysozyme.
- Assessment of T-cell responses to native lysozyme, unfolded lysozyme, and synthetic antigenic sites.
- Major histocompatibility complex (MHC) restriction analysis of T-cell responses.
Main Results:
- T-cell lines and clones responded strongly to native lysozyme but poorly to unfolded lysozyme.
- T-cell responses were MHC-restricted.
- Specific T-cell clones recognized synthetic peptide sequences mimicking surface-exposed antigenic sites on native lysozyme.
Conclusions:
- T-cell recognition of protein antigens is exquisitely dependent on the antigen's native conformation.
- Native, unprocessed protein antigens, not just processed fragments, can trigger MHC-restricted T-cell responses.
- This suggests a more direct role for intact protein structures in initiating adaptive immunity.