FIG. 8.

Recombinant GroEL from F. tularensis Schu S4 elicits marginal production of CXCL8 by human macrophages. HuMDM were stimulated with 1 or 10 μg of GroEL/ml from the LVS or the Schu S4 strain for 24 h at 37°C in the presence of 20 μg of polymyxin B/ml. For controls, cells were incubated with either 10 ng of E. coli (Ec) LPS/ml or medium only (Unstim). Cell-free, conditioned media were collected and assayed for CXCL8 by ELISA. Bars indicate the means ± the SD of three replicate samples. *, Significantly greater than unstimulated samples (P < 0.01); **, significantly greater than unstimulated samples (P < 0.001). This experiment was repeated two more times with similar results.