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Unconventional topology of self peptide–major histocompatibility complex binding by a human autoimmune T cell receptor

2005; Nature Portfolio; Volume: 6; Issue: 5 Linguagem: Inglês

10.1038/ni1187

1529-2916

Michael G. Hahn, Melissa J. Nicholson, Jason W. Pyrdol, Kai W. Wucherpfennig,

Immunotherapy and Immune Responses

Autoimmune diseases are caused by self-reactive lymphocytes that have escaped deletion. Here we have determined the structure of the trimolecular complex for a T cell receptor (TCR) from a patient with multiple sclerosis that causes autoimmunity in transgenic mice. The structure showed a TCR topology notably different from that of antimicrobial TCRs. Rather than being centered on the peptide–major histocompatibility complex, this TCR contacted only the N-terminal peptide segment and made asymmetrical interactions with the major histocompatibility complex helices. The interaction was dominated by the hypervariable complementarity-determining region 3 loops, indicating that unconventional topologies are possible because of the unique complementarity-determining region 3 sequences created during rearrangement. This topology reduces the interaction surface with peptide and alters the geometry for CD4 association. We propose that unusual TCR-binding properties can permit autoreactive T cells to escape deletion.