Effect of chondroitinase AC digestion on the IL-1β–inducing activity of CSA. CSA (10 mg/mL) or HA (50 μg/mL) was incubated with chondroitinase AC (100 mU/mL) in RPMI (without fetal calf serum) at 37°C for 2 hours. The reaction mixtures were then postincubated at 65°C for 10 minutes to inactivate the enzyme. PBMC were cultured in the presence of untreated and chondroitinase AC-treated CSA (1 mg/mL) or HA (5 μg/mL) for 24 hours and the level of IL-1β in the medium was determined as in Fig 1.