Chemotactic activity of supernatants derived from monocytes stimulated with IL-15 for PMN (A) or monocytes (B). (▪) Supernatants treated with control IgG. (▨) Supernatants treated with anti-IL-8 or anti-MCP-1 neutralizing antibodies. Results represent mean ± SE of three independent experiments. *Significant chemotactic response in comparison to medium (P < .05). †Significant inhibition by treatment with neutralizing antibodies in comparison to treatment with control IgG (P < .05).