FIG. 6.
Effect of imipenem treatment on TNF-α secretion from macrophages stimulated by E. coli versus S. aureus. C3Heb/FeJ mouse macrophages were cocultured with 5 × 105 CFU of viable E. coli O111:B4 or viable S. aureus M/ml, with (■) and without (□) imipenem (50 μg/ml), for 0 to 6 h. (a and d) TNF-α in supernatants collected at 0 to 6 h, assayed as described in Materials and Methods. (b and e) Secondary plots of the data in panels a and d, respectively. Specifically, from each datum shown in panels a and d, the experimental value for TNF-α determined at the immediately preceding experimental time point has been subtracted. (c and f) Serum TNF-α data taken from reference 24, shown here on a log scale, from the trunk blood of outbred (CF-1) mice challenged intraperitoneally with the same proliferating bacterial strains as those used in the present study and concomitantly with a second intraperitoneal injection of 20 mg of imipenem per kg of body weight. For the in vitro data, three independent experiments were performed; for the in vivo data, two experiments were performed, with five mice per datum per experiment. Data are means ± SEM, ∗ P < 0.05; ∗∗, P < 0.005. For the data lacking error bars, variation was too small to indicate.