SELE and major depressive disorder: Many studies have also demonstrated an increase in serum concentrations of immune signaling molecules (chemokines and adhesion molecules), soluble intracellular adhesion molecule-1 and E-selectin, as well as acute phase proteins and proinflammatory cytokines (e.g., IL-6 or proinflammatory cytokines, prostaglandin) in patients with depression, suggesting that the immune system is involved in depression (Miller and Raison, 2016).