Clinical depression is often associated with the change of immune response, including the number of circulating white blood cells, lymphocytes, neutrophil phagocytosis decreased, the phagocytosis of mononuclear cells increased, this a series of immune cells in the process of change, along with the numerous changes of immune inflammation factors, such as TNF-α, CRP, IL-6, SAA, and INF-γ [28, 29]. Here, CRP is linked to major depressive disorder.