Importantly, mice immunized with the LMA vaccine first had the largest amount of secreted IL-17 during the postinfection time point, which, combined with decreases in CXCL1, RANTES, and G-CSF and increases in CCL2, CCL4, and GM-CSF, could have a critical role during productive versus nonproductive stages of pneumonic plague. Here, CCL2 is linked to pneumonic plague.