RNAse protection assay on dermal fibroblasts and synoviocytes stimulated by human TNF-like weak inducer of apoptosis (hTWEAK) or tumour necrosis factor (TNF) in the presence of anti-TWEAK or anti-TNF mAbs. Polymyxin B-treated cells were cultured for 16 hours in the presence of 50 ng/ml TWEAK or 10 ng/ml TNF alone or in association with 10-7 M of the anti-TWEAK mAbs BCB10 or BEB3 (10 μg/ml) or anti-TNF mAb (10-7 M). Total RNA was extracted and tested by RNAse protection assay. Similar results were obtained in four independent experiments on dermal fibroblasts and two experiments on synoviocytes. GAPDH, glyceraldehyde-3 phosphate dehydrogenase; IP-10, interferon-γ-inducible protein-10; L32, housekeeping gene present in hcK5 template from Pharmingen; MCP, macrophage chemoattractant protein, MIP-1α, macrophage inflammatory protein-1α; RANTES, regulated on activation, normal T expressed and secreted.