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Alloreactive CD8+ T cells can recognize unusual, rare, and unique processed peptide/MHC complexes
S Malarkannan1, F Gonzalez, V Nguyen
1Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|November 15, 1996
Summary
Researchers identified a rare self-peptide (adenosine phosphoribosyl transferase) that alloreactive T cells recognize, revealing insights into T cell receptor specificity and peptide-MHC interactions.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- The ligands recognized by alloreactive T cells are largely unknown.
- Understanding these interactions is crucial for transplant rejection and autoimmune disease research.
Purpose of the Study:
- To identify the self-peptide/MHC class I complexes recognized by Kb-restricted alloreactive T cells.
- To investigate the binding and presentation of these complexes.
Main Methods:
- Expression cloning using Kb-restricted alloreactive T cells as a probe.
- Peptide identification and characterization.
- Analysis of peptide binding to MHC class I and expression levels.
Main Results:
- Identified adenosine phosphoribosyl transferase (APRT) as the antigen precursor gene.
- The naturally processed peptide was SLVELTSL (SEL8), which bound tightly to Kb MHC despite lacking a key anchor residue.
- SEL8 was expressed at very low levels (<10 copies/cell).
- Mutations in APRT reduced T cell stimulation by antigen-presenting cells (APCs).
Conclusions:
- Peptide/MHC complex display on cells can exceed predictions based on consensus motifs.
- CD8+ alloreactive and conventional antigen-specific T cells recognize unique and rare peptide/MHC class I complexes similarly.