Abstract

Patients must meet 5 out of the 9 criteria for major depressive disorder and have them present for at least two weeks in order to receive a diagnosis. The severity of depression and its impact on quality of life are influenced by how severe the symptoms of depression are. There will likely be an increase in the prevalence of major depressive disorders (MDD), which are considered to be serious health issues. Interleukin IL-6 and tumor necrosis factor (TNF-), which are classified as pro-inflammatory cytokines and can activate an inflammatory response, are immune cytokines that have been linked to serious depression, for example. There is debate regarding other inflammatory cytokines' impact on the central nervous system. The impact of cytokines produced by the innate immune system on the brain and behaviour is a topic of growing study. Large-sized proteins known as cytokines are typically produced by immune cells. Proinflammatory cytokines, which facilitate inflammatory responses and neural activity, and anti-inflammatory cytokines, which suppress inflammatory processes, are the two subtypes of cytokines. Immune cells including monocytes, macrophages, and lymphocytes, in addition to microglia and astrocytes, also produce cytokines. Cytokines are in an activated state during immune system changes, infections, or inflammation. The primary objective of the current review study is to examine how the immune system contributes to depression disorder.