CXCL8 and rheumatoid arthritis: Monocytes/macrophages are the most crucial antigen-presenting cells (APCs), secreting a variety of cytokines (TNF, IL-6, IL-1, and IL-8), growth factors, and chemokines, which influence RA pathophysiology (MCP1, VEGF, GM-CSF, and MIP-1) [51,52].