Trafficking of FoxP3+ regulatory T cells: myths and facts

Fork head box P3 (FoxP3(+)) regulatory T cells (Tregs) are specialized T cells for prevention of hyperimmune responses and autoimmunity. Tumors and pathogens can hijack FoxP3(+) Tregs to evade host immune responses. There is an increasing body of evidence that trafficking of FoxP3(+) Tregs is important for their effective suppression of target cells. Because of their distinctive functions and gene expression phenotype, the migratory behavior of FoxP3(+) Tregs has been somewhat mystified. The myths are that they have unique trafficking receptors and migratory behaviors that are different from those of conventional T cells. Another related myth is that FoxP3(+) regulatory T cell subsets have a fixed trafficking behavior from the time they are generated in the thymus. The recent progress in trafficking receptors and migratory behavior of FoxP3(+) Tregs is reviewed here and the validity of these myths is examined.