Plasma IL-12 levels are suppressed in vivo by stress and surgery through endogenous release of glucocorticoids and prostaglandins but not catecholamines or opioids.
Shaashua L, Rosenne E, Neeman E, Sorski L, Sominsky L, Matzner P, Page GG, Ben-Eliyahu S.
Psychoneuroendocrinology