Production of TNFα, IL-10, IL-12, and IL-8 upon challenge of primary human monocytes. Monocytes were isolated from human whole blood and cells (1 × 106/ml) were challenged with varying doses of gentamicin-killed gonococci. Sample supernatants were collected at 18 hrs post challenge and cytokines were analyzed by ELISA. Clear bars indicate challenge with F62ΔlgtD and shaded bars indicate challenge with F62ΔlgtA Challenge with media alone resulted in no measurable TNFα or IL-10 and less than 100 pg/ml IL-12; Approximately 1 ng/ml IL-8 was measurable from negative controls, with a standard error of 0.8 ng/ml. (A) TNFα (B) IL-10 (C) IL-8 (D) IL-12 These data represent three experiments, each performed in triplicate. Error bars indicate the standard error of the mean.