Time-dependent effect of antagonizing IL-1 activity. Cartilage was cultured as described for Figure 1. IL-1βmAb (A, C, E; n = 7) or IL-1RA (B, D, F; n = 7) was added at the moment of blood exposure or 2 to 48 hours later. Proteoglycan synthesis rate (A, B), release (C, D), and content (E, F) are depicted. Dotted line represents control conditions (cartilage cultures without additives). #P < .05 compared with control values; *P < .05 compared with blood-exposed cartilage without IL-1βmAb or IL-1RA addition.