TNFα-treated DC express a high level of CD83. Compared with non–TNFα-supplemented 14-day DC cultures (shaded histograms), the addition of TNFα (at day 7) resulted in strong expression of the mature DC marker, CD83, by FACS analysis (dotted open histograms). Compared with isotype-matched control monoclonal antibody staining, both TNFα-treated and non–TNFα-treated DC did not show a notable change in high-level CD45RO expression and remained negative for CD14 and CD25 expression. The x-axis is a logarithmic scale of fluorescence intensity and the y-axis represents counts. Similar results were obtained in a second repeat experiment.