CD69 and infection: In contrast, BALF and lung samples from mice with heat-killed DK128 pretreatment showed lower levels of monocytes (F4/80+CD11c−CD11b+Ly6ChiSiglecF−), natural killer cells (F4/80−DX5+CD69+), and activated natural killer cells (F4/80−DX5+CD69+) (Fig. 3b–d,f–h), while naïve untreated-mice showed significantly enhanced recruitment of monocytes, natural killer cells, and activated natural killer cells in response to the lethal infection with A/Philippines (H3N2) virus (Fig. 3b–d,f–h).