role in the prevention of autoimmunity. Here, we present data arguing that the forkhead
transcription factor Foxp3 acts as the regulatory T cell lineage specification factor and
mediator of the genetic mechanism of dominant tolerance. We show that expression of
Foxp3 is highly restricted to the subset αβ of T cells and, irrespective of CD25 expression,
correlates with suppressor activity. Induction of Foxp3 expression in nonregulatory T cells …