Basic and acidic fibroblast growth factor (bFGF and aFGF, respectively) and vascular endothelial growth factor (VEGF) exert angiogenic actions and have a role in wound healing, inflammation, and tumor growth. Monocytes and endothelial cells are involved in these processes, but the effect of FGF and VEGF on monocyte-endothelial cell interactions has not been defined. We observed that monocyte adhesion to resting or cytokine (tumor necrosis factor-alpha or interleukin-1 alpha)-stimulated human umbilical vein endothelial cells (HUVECs) was markedly inhibited (40 to 65%) by culture (1 to 6 days) of HUVECs with aFGF or bFGF. Monocyte transendothelial migration induced by C5a and chemokines (MCP-1, SDF-1 alpha, RANTES, MIP-1 alpha) was also suppressed (by 50 to 75%) on bFGF-stimulated HUVECs. VEGF did not have these effects at the concentrations used (10 to 20 ng/ml), although like bFGF, it promoted HUVEC proliferation. Culture of HUVECs with bFGF and aFGF significantly down-regulated intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin expression on resting or tumor necrosis factor-alpha-stimulated HUVECs, but had no influence on platelet endothelial cell adhesion molecule (PECAM)-1 and VE-cadherin expression. bFGF also inhibited MCP-1 production by HUVECs. The inhibitory effects of bFGF on monocyte transendothelial migration and adhesion molecule expression were reversed by SU6668, an anti-angiogenic agent and bFGF receptor tyrosine kinase inhibitor. Our results suggest that bFGF and aFGF may suppress endothelial-dependent monocyte recruitment and thus have an anti-inflammatory action during angiogenesis in chronic inflammation but inhibit the immunoinflammatory tumor defense mechanism. However, SU6668 is an effective agent to prevent this down-regulatory action of bFGF on monocyte-endothelial cell interactions.