Influence of LPS on uptake of fluorescently labeled catalase. Murine clone 4-4 macrophages were stimulated with vehicle or different concentration of LPS for 45 minutes at 37°C and 5% CO2 in the presence of 6.6 mg/mL fluorescent catalase to assay pinocytosis (open circles) or fluorescent catalase and a mixture of three different supernatants of hybridomas producing antihuman catalase antibodies to assay Fc receptor–mediated uptake (filled circles). Uptake of fluorescence was then determined using FACS analysis. To distinguish uptake from binding, parallel experiments were performed at 4°C. The results show the average and standard error of four different experiments, each experiment being the average of two independent determinations. (A) Effects of different LPS concentrations. (B) Effects of different LPS concentrations in TNF (500 U/mL)-stimulated macrophages. (C) Effects of LPS on TPA (100 ng/mL)-stimulated macrophages.
