Analyses of the cytokine production (MCP-1 and TNF), macrophage infiltration (estimated by Adgre1 (F4/80) expression), and Nos2 (iNOS) induction in the infected lungs detected a higher expression of Ccl2 (MCP-1; Fig. 7d), Adgre1 (Fig. 7e), and Nos2 (Fig. 7f) in Trem2−/− mice than in WT mice at day 3 after infection. Here, CCL2 is linked to infection.