Immune to autoimmunity

New results from Antoine Perchellet, Joan Goverman, and colleagues (University of Washington, Seattle, WA) show that T cells that bind self-peptides most avidly can survive and engulf self-peptides without initiating an autoimmune response. Although appearing innocent, these cells might be potential disease instigators.

Most self-recognizing T cells whose receptors interact too strongly with self-peptides are either killed or made unreactive (by receptor rearrangement) in the thymus. If they somehow escape to the bloodstream, they can also be killed or silenced there. To study how these processes eliminate T cell responses to myelin basic protein (MBP), a target of T cells during multiple sclerosis, the authors created two mice lines that express different MBP-specific T cell receptors.

One receptor, which had a lower affinity for MBP, worked as...