To test this hypothesis, we analysed infection in both cell types via flow cytometry, identifying neutrophils as CD45+CD11b+Ly6G+ and macrophages as CD45+Ly6G−SiglecF−CD64+CD11b+CD11cINT;22,23 Supplementary Fig. 3) Interestingly, we found that the increased bacterial burden in CD200R−/− mice was restricted to neutrophils, alongside a dramatic increase in neutrophils (both as a % and absolute number) in the infected CD200R−/− lung at days 5 and 7 p.i. (Fig. 2d, e and Supplementary Fig. 4A, B). This evidence concerns the gene CD200R1 and infection.