H. polygyrus infection induces bone marrow monopoiesis.
Under normal physiological conditions, murine classical monocytes have a half-life of just over one day in the circulation, with constant replenishment from the bone marrow27,28. To understand if the monocytosis in blood during H. polygyrus infection reflected changes at the level of bone marrow haematopoiesis, we used colony forming assays to assess the progenitor lineage potential duringH. polygyrus infection. Four days post infection there was an increase in the number of monocyte-committed progenitors (Colony Forming Unit – Monocytic; CFU-M) compared to uninfected controls (Fig. 3A). Although this elevation was short lived and lost by 10 dpi (Fig. 3B), enumeration of classical monocytes (Lin-, CD16/CD32+, CD117-, CD115+, Ly6C+, Fig. 3C) in the bone marrow confirmed that their numbers increase in the context of H. polygyrus infection (Fig. 3D).