MMP-9 levels were estimated quantitatively by computerized two-dimensional scanning densitometry using a standard curve. Lanes 1–5 represent a dilution of purified human MMP-9 (100, 50, 15, 5, and 1.5 ng respectively). Lanes 6–8 represent 3-μl plasma samples taken at 15, 30, and 45 min after a single bolus injection of 0.1 mg/kg IL-8.