Nitric oxide (NO) side of lymphatic flow and immune surveillance.

T he loss of cancer or bacteria detection by the immune system is traditionally looked at from the point of cell–cell or humoral mediator–cell interactions. However, immune surveillance in lymphatics critically requires cell transport along the lymphatics for entry of antigen/dendritic cells into the draining lymph node (1). Reductions in collecting lymphatic function affect all subsequent immune response. The work by Liao et al. (2), from a team wellversed in the complexities and limitations of transport in tumors, brings to light that lymphatic transport can be limited by a mechanism that is controlled by nitric oxide (NO) derived from bone marrow myeloid cells.