Monocyte chemotactic protein-3 (MCP-3) is a C-C chemokine which interacts with the CCR1, CCR2 (MCP-1) and CCR3 receptors and has a distinct spectrum of action. The present study was designed to investigate whether human endothelial cells (EC) and, by way of comparison, monocytes express MCP-3 and its regulation by pro- and anti-inflammatory cytokines. Unstimulated human umbilical vein EC and monocytes did not express MCP-3. Bacterial lipopolysaccharides (LPS), IL-1 and TNF induced low, but appreciable levels of MCP-3 transcripts. Interferon-gamma was a much weaker, but nevertheless active, inducer. MCP-3 transcripts were considerably less abundant than those for MCP-1. IL-4, IL-13 and IL-10 did not induce MCP-3 expression. These anti-inflammatory cytokines suppressed cytokine-induced MCP-3 expression in monocytes. In contrast, IL-4, IL-13 and IL-10 either did not affect or they amplified MCP-3 induction in EC. EC-produced MCP-3 may be important in the regulation of extravasation of receptor-expressing cells, including NK cells and eosinophils.