Serum levels of IL-12, IFN-γ, and IP-10. Shown are serum levels of (A) IL-12, (B) IFN-γ, or (C) IP-10 at entry and 18 hours after the first dose of IL-12 in patients receiving 300 ng/kg, 500 ng/kg, or 625 ng/kg IL-12. Each point depicts a serum concentration in a single patient; the lines show the median values. The dotted lines depict the lower limit of detection for each assay.