CCL2 and major depressive disorder: A range of pro-inflammatory cytokines (TNFa, IL-6,), chemokines (TARC, Mip1a, MCP1, MCP4) chemoattractant (sICAM1) and acute phase (SAA) proteins are associated with the somatic symptoms of depression, with IL-6 and SAA showing decreases alongside therapy only in participants with a predominantly somatic subtype.