We investigated the effects of various sulfhydryl compounds on interleukin-1 (IL-1)-induced vascular endothelial growth factor (VEGF) production in human synovial stromal cells (HSSC). HSSC stimulated by IL-1beta (100 ng/ml) produced VEGF and interleukin-6 (IL-6) in vitro. Monosulfhydryl compounds, N-acetylcysteine, D-penicillamine, tiopronin and the bucillamine-like disulfhydryl compound, compound A scarcely affected VEGF or IL-6 production at concentrations of 10(-5) and 10(-4) M. However, the disulfhydryl compound, bucillamine inhibited VEGF production but not IL-6 production at concentrations of 10(-5) and 10(-4) M. These results suggest that bucillamine may be a selective inhibitor of IL-1-induced VEGF production in HSSC, and that inhibition of VEGF production may require not only SH groups but also a specific chemical structure.