IL6 and major depressive disorder: While individual studies have reported variable results both in favor and against, the meta-analysis strengthened the case in favor of depression’s association with inflammatory response system.17 This is supported by other studies such as a meta-analytic review reporting increased circulating IL-6 levels in depression18, and the WFSBP Task Force on Biological Markers study revealing a robust association with increase of soluble interleukin-2 receptor and interleukin-6 in serum, and impaired suppression of the dexamethasone suppression test.19