Figure 1

Principle of the bioassay. Rheumatoid arthritis synoviocytes (10⁴ cells/well) were cultured in 96-well plates and stimulated with increasing doses of tumour necrosis factor (TNF)-α (0–100 ng/ml). Levels of (a) IL-6 and (b) osteoprotegerin (OPG) were measured in 48-hour supernatants. Infliximab at 10 μg/ml was preincubated for 1 hour with TNF-α before its addition to the culture.