Fig. 1.

Co-culture with scleroderma fibroblasts promotes U937 cell migration across endothelial cell (EC) monolayers. Leucocyte migration is expressed as mean percentage (± s.e.m.) of added cells migrating across control EC monolayer over 16 h. Data are from replicate wells in six independent experiments using six different scleroderma (SDF) and three normal fibroblast (NDF) strains. Cells were counted directly using a haemocytometer. Cytokine activation (tumour necrosis factor-alpha (TNF-α) 100 U/ml for 8 h) is indicated by EC+ and SDF+. *Significantly greater than migration across resting EC layer; **greater than migration across activated EC layer (Student's paired t-test, P < 0.05).