FIGURE 9.

Reducing the m.w. of B. anthracis PGA results in reduced cytokine responses from human monocytes. (A) B. anthracis PGA was sonicated to reduce its m.w., electrophoresed on a 1% agarose gel, and visualized by 0.1% methylene blue staining. Gel order is as follows: 1) untreated B. anthracis PGA, 2) sonicated B. anthracis PGA, 3) B. subtilis PGA exposed to monocytes, and 4) B. licheniformis PGA exposed to monocytes. A representative gel is shown (n = 3). (B) Human monocytes were exposed to 500 μg/ml untreated or sonicated B. anthracis PGA. Media samples were analyzed for cytokines. An increase of ≥50% over the unstimulated control was considered a response. Five experiments were run using cells from five donors (n = 5). The range of individual responses for each cytokine are presented in picograms per milliliter plus the number of donors that had a response. (C and D) Data are presented as geometric means in picograms per milliliter ± geometric SD (n = 5) for IL-8 (C) and IL-6 (D), which were the only significant cytokines. Statistical significance of responses to untreated and sonicated B. anthracis PGA compared with the unstimulated control and the differences in responses to untreated versus sonicated B. anthracis PGA were determined by paired t tests of the log transformed data. *p < 0.05, **p < 0.01.