To provide further evidence that neutrophils and not other contaminating cells such as monocytes produced IL-1β in these cultures, purified neutrophils from pIL1-DsRed reporter mice were evaluated in this in vitro infection and 43% of the Ly6G+ neutrophils expressed IL-1β-DsRed whereas only 0.2% of other cell types (Ly6G− cells) expressed IL-1β-DsRed (Fig. S10). This evidence concerns the gene IL1B and infection.