IL6 and infection: Infection of hBMEC with the ΔpXO1 strain restored secretion of IL-8 and CXCL1 to levels secreted by uninfected cells, while IL-6, CXCL2, and CCL20 protein expression levels did not differ in the absence of the pXO1 plasmid compared to B. anthracis Sterne-infected hBMEC, suggesting that additional chromosomal factors may influence protein expression (Fig. 5B).