Control of Immune Responses by Naturally Arising CD4+ Regulatory T Cells That Express Toll-like Receptors

It is a key issue in immunology to understand how the immune system discriminates between self- and nonself, inhibiting autoimmune responses but allowing the host to mount immune responses against invading microbes ([1][1]–[3][2]). This is due to the fact that once antigen-specific lymphocytes are