CCL2 and Arthritis: Nevertheless, both MCP-1 (a monocyte and T lymphocyte chemoattractant) and IL-12 (a heterodimeric cytokine produced by macrophages and dendritic cells) have a central role in cell-mediated immune responses and have been linked to the progression of autoimmune diseases such as arthritis and multiple sclerosis 41,43,56,57.