A happy mood helps to build a flourishing immune system.Interactions between the nervous and immune systems have attracted the interest of researchers for decades.It is well known that external stressors can activate the hypothalamus to regulate immune responses via the hypothalamic-pituitary-adrenal cortex (HPA) axis [1].As well, inflammatory stimuli can activate a rapid antiinflammatory reflex via the cholinergic vagus nerve pathway.An important target for the nervous systemelicited immune regulation is the spleen, a key organ where immune cells meet pathogens and antigens to trigger innateand adaptive immune responses.