Research highlight

Viral triggers to autoimmunity

Nature Immunology

June 7, 2010

Understanding why some individuals develop autoimmunity but others do not has long puzzled researchers. The culprits appear to be immune cells that bear two distinct recognition receptors according to a report published this week in Nature Immunology.

T cells, a component of the immune system, express surface receptors called TCRs that can recognize protein fragments displayed on target cell surfaces. Each T cell expresses a unique TCR that possesses a unique specificity. Joan Goverman and colleagues show some CD8+ T cells express two different TCRs: one specific for a viral peptide but a second that recognizes a brain-specific myelin peptide. Mice that possess these dual-TCR-expressing T cells infected with virus develop autoimmune encephalomyelitis, a model for the human disease multiple sclerosis.

Importantly, the scientists rule out previously suspected reasons for why viral infection triggers autoimmunity. The viral-specific TCR activates the T cell, which then circulates through the body seeking out virally infected cells to destroy and these armed T cells attack myelin-expressing cells through recognition by their second TCR.

Although Goverman and colleagues look at how viral infection triggers encephalomyelitis, their results might also explain how other autoimmune diseases are triggered.

doi: 10.1038/ni.1888

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