Living T-helper cells differentially induce IL-8, MCP-1, and IP-10 by fibroblasts cultured in transwell chambers. Fibroblasts were plated at 1.5 × 104 cells in the upper transwell chamber; 72 hours later the culture medium was replaced and T cells (1 × 106) were plated in the lower transwell chamber previously coated with anti-CD3 mAb. Chemokine levels were determined by enzyme-linked immunosorbent assay in 48-hour supernatants. TNF-α (100 ng/ml) was used as a positive control in wells without T cells. Anti-TNF (soluble TNF receptor I; 10-8 mol/l), IL-1 receptor antagonist (2 μg/ml) and anti-IFN-γ (10 μg/ml), alone or in combination, were added to the lower wells 30 minutes before T cells. The bars represent the mean of duplicate wells. Note that the scale is different in each panel and for IP-10 it is 100 times smaller for Th2 than for Th1 cells. Similar results were obtained in an additional experiment. IFN, interferon; IL, interleukin; IP, interferon-γ inducible protein; MCP, monocyte chemoattractant protein; Th, T-helper; TNF, tumour necrosis factor.