T cell mediated neuroprotection is a physiological response to central nervous system insults

The physiological conditions under which beneficial autoimmunity is evoked have never been documented. We recently demonstrated that autoimmune T cells directed against myelin-associated self-proteins, when passively transferred into rats or mice, reduce the spread of damage after traumatic injury to central nervous system axons. This finding raised a fundamental question: does this beneficial effect represent a physiological neuroprotective response that normally is too weak to be effective and requires boosting, or is it simply the welcome result of an ex vivo manipulation? It appears from our studies that trauma, at least in the central nervous system, evokes a stress signal that activates a T cell dependent response directed against self antigens, and that this response is physiological in nature, beneficial in intent, and amenable to boosting by active or passive immunization.