Ly6Chi and Ly6Clow blood monocytes from naïve and Heligmosomoides polygyrus bakeri infected mice

The degree to which the circulating monocyte compartment responds to infections that initiate alternative types of response is poorly understood. Here we describe a unique state of the monocyte compartment associated with type 2-favouring intestinal helminths.

The adapted monocyte state in a type 2 setting was associated with an interferon-signature. Acquisition of this interferon-induced state provided helminth-infected animals with unappreciated systemic protection against secondary bacterial infection, but still allowed for the development of effective type-2 immunity. This pathway of monocyte education was completely distinct from that described in Th1-settings and involved an endogenous-bacteria-mediated induction of type I IFN that led to adaptive lymphocyte-dependent IFN- priming of monocytes.