Old and “hangry” monocytes turn from friend to foe under assault

Fasting is known to impact monocyte dynamics and phenotype, but the mechanics and functional significance of this response remain unclear. In this issue of Immunity, Janssen and colleagues demonstrate that fasting and re-feeding causes monocytes to re-enter the bone marrow and alter the host response to infection. Fasting is known to impact monocyte dynamics and phenotype, but the mechanics and functional significance of this response remain unclear. In this issue of Immunity, Janssen and colleagues demonstrate that fasting and re-feeding causes monocytes to re-enter the bone marrow and alter the host response to infection.