Focusing on the AM Pro-Infl cluster, we identified a conserved gene signature expressed by this subpopulation irrespective of infection status (Ftl1, Fth1, Fabp5, Lyz2, CD68, and Cd63; Fig. 6, a and b; and Fig. S2 e), suggesting this subpopulation of pro-inflammatory AMs is already present in the lungs of uninfected mice (and humans, as detailed previously). Here, FTH1 is linked to infection.