In addition to the psychological response to the diagnosis, some studies indicate a relationship between depression and the disease process itself, specifically with biomarkers of inflammation in the blood (cytokines, including interleukin-6, which is a signalling particle responsible, among others, for initiation and development of the inflammatory response, induction of acute phase protein synthesis, or activation and differentiation of T lymphocytes). This evidence concerns the gene IL6 and major depressive disorder.