APC and infection: Furthermore, by intravenous administration of anti-CD45-APC antibody to label circulating blood cells during PVM infection, we confirmed that the LIF-dependent immune cell deficit in the MedLN had resulted from their impaired migration from the lungs via the lymphatic system, although the magnitude of the immune response to infection was smaller in these experiments, leading to more modest differences between LIF-cKO mice and controls (Extended Data Fig. 3e–j).