CD209 and infection: Our observation that DC-SIGN interaction confers longevity to PDDCs supports the existence of this mechanism in vivo. Our results show that a novel subset of cell, PDDCs, are long-lived and dys-regulated immune cells with a unique ability to modulate immunity based on very specific host-pathogen interaction.In conclusion, we have identified an important new pathway whereby chronic low-grade (oral) infections can negatively influence immune surveillance through host modulation.