FIG. 7.
IL-12 p40 is produced by DC coincubated with serovar Typhimurium or with purified LPS. (A) DC were stimulated with viable wild-type, phoP, or phoPc serovar Typhimurium; viable wild-type serovar Typhimurium in the presence of CCD; or heat-killed wild-type serovar Typhimurium or were incubated in medium alone, as indicated. After an initial 2-h pulse with the bacteria, the cells were washed, treated with gentamicin, and incubated an additional 46 h. At this time point, the relative level of the IL-12 p40 subunit in the culture supernatant was quantitated by sandwich ELISA. (B) DC were either incubated in medium only or in the presence of 1-μg/ml LPS purified from wild-type, phoP, or phoPc serovar Typhimurium, as indicated. After 48 h of total incubation time, the relative level of the IL-12 p40 subunit was quantitated in culture supernatant by sandwich ELISA. Data are presented as the means of triplicate samples ± 1 standard deviation. Similar results were obtained in at least three independent experiments.