Regulation by IL-4 and IFN-γ of MCP-1 production by IL-15–stimulated monocytes. Monocytes were incubated under the conditions described in the Fig 3 legend. After 6 hours supernatants were assayed for IL-8 content by ELISA. Results represent mean ± SE of MCP-1 concentrations of three independent experiments. *Significant difference of MCP-1 concentrations (P < .05). †Significant inhibition by treatment (P < .05).