CCL4 and idiopathic pulmonary fibrosis: Moreover, our study yielded robust null results for circulating inflammatory cytokines (IL-1ra, IL-2ra, IL-2, IL-6, IL-8, IL-10, IL-18, MIP1a, MIP1b, MCP1, RANTES, TANLN, and CXCL9), indicating that prolonged exposure to elevated levels of these circulating inflammatory cytokines does not increase the risk of IPF.