Chronic stress is known to negatively affect immune function.95 Since chronic life stress is difficult to define or control in humans, the majority of studies were conducted in rodents.96 Prolonged wet-cage exposure or continuous administration of β2-AR agonists disrupted the immunostimulatory effects of IL-12 on NK cells in rats.97 Another study suggested a role for epinephrine in leukemia progression through reduced NK activity in chronically stressed rats.98 In addition to tumor control, β2 adrenergic signaling was shown to affect NK cell function against viral infections. This evidence concerns the gene ADRB2 and neoplasm.