Hospitalization due to any reason or medical condition is associated with fear, anxiety, and depression. psychological and physiological factors have a significant impact on hospitalization outcomes. Many depressed patients do not complain of dysphoric mood, and their predominant clinical features present as anxiety, physical complaints, fatigue, and genital symptoms such as changes in sleep and appetite, or as psychosis. But the physical symptoms of depression are less noticeable. The prevalence of this disorder in medical and surgical departments is 2 to 3 times higher than its prevalence in the general population. Immune system disorders are one of the most important problems that depression causes. Studies show that depression, on the one hand, suppresses the appropriate response to infectious agents by inducing the responses of type 2 helper T lymphocytes (responses involved in causing allergies), and some antibody-dependent autoimmunity, and on the other hand Causes chronic and destructive inflammation by the immune system. Given the functional importance of inflammatory cytokines as well as studies in previous studies on the relationship between inflammatory cytokines and major depressive disorder, we will focus more on studies on the role of interleukin 2 in the pathophysiology of major depressive disorder in hospitalized patients. hospitalization generally exposes the patient to inflammation. Studies show an increased risk of inflammation following hospitalization of patients, and many studies confirm the association of major depression with inflammatory cytokines and, more concentrated, interleukin-2.