Greter et al22 demonstrated that in csf2r−/− mice, infDC (defined as MHC-II+CD11cintCD11b+Ly6c+) developed normally in response to influenza and Streptococcus pneumoniae while Campbell et al42 have shown that infDCs defined by the same surface markers are absent from the synovial tissue and lymph nodes of GM-CSF−/− mice after induction of acute monoarticular arthritis. Here, CSF2 is linked to arthritic joint disease.