A number of cytokines are active during the evolution of an inflammatory response, including tumor necrosis factor-alpha, interleukin-1, and novel chemotactic cytokines. This latter group of mediators belong to supergene families of inflammatory signals that play a key role in the selective recruitment of immune cells. In this presentation, we present data demonstrating, for the first time, endothelial cell expression of monocyte chemotactic protein (MCP) mRNA induced by LPS, interleukin-1 or tumor necrosis factor. Human fibroblasts were also found to express monocyte chemotactic factor mRNA in response to interleukin-1 or tumor necrosis factor, but LPS was not effective. In addition, neither primary cultures expressed MCP in response to interleukin-6. These studies demonstrate that non-immune "bystander" cells can play an active role in the recruitment of inflammatory cells via the production of novel chemotactic cytokines.