CXCL8 and rheumatoid arthritis: Moreover, human RA synovial explants were incubated with 1 nM, 10 nM, or 100 nM of RvE1, and cytokine levels (IL-1β, IL-6, IL-8, IL-10, INF-γ, and TNF-α) were measured using Luminex bead array.