CCL4 and systemic inflammatory response syndrome: As indicated above, development of SIRS in sepsis refers to the presence in plasma of proinflammatory mediators, such as TNF-α, IL-1β, IL-6, IL-18, IL-8 as well as MCP-1 (CCL-2), MIP-1α (CCL3), MIP-1β (CCL4), etc. Some of these mediators are chemotactic for PMNs and monocytes, while others are chemotactic for T cells.