Effects of detoxified LPS on macrophage fluid phase uptake. Murine clone 4-4 macrophages were stimulated with LPS (open circles) or detoxified LPS (closed circles) for 45 minutes at 37°C and 5% CO₂ in the presence of [³H]sucrose. Subsequently, the cells were placed on ice and washed, and accumulated radioactivity was determined by scintillation counting. Using the specific activity of the [³H]sucrose, fluid phase uptake was expressed as femtoliter per cells per minute.