Studies performed on healthy volunteers have revealed that catecholamines down-regulate the lipopolysaccharide (LPS)-induced production of tumor necrosis factor (TNF)alpha, interleukin (IL)-6, and IL-1beta. We extended this observation and show that this effect is based on changes in the mRNA concentration of these cytokines. Catecholamines are increased in severe sepsis due to endogenous production and have to be administered exogenously when the disease has proceeded to the state of prolonged hypotension. We here investigated whether the immunomodulating effect of catecholamines could also be demonstrated in the blood of patients with prolonged severe sepsis and of those in prolonged septic shock. Blood was stimulated ex vivo with LPS in the presence and absence of epinephrine and the cytokine protein concentration was determined. In blood of healthy volunteers, epinephrine reduced the LPS-stimulated synthesis of TNFalpha by 62.5% (P< 0.0001), of IL-6 by 39% (P< 0.0001), and of IL-1beta by 40% (P= 0.015), and increased the LPS-stimulated IL-10 production by 77.8% (P < 0.0001). Correspondingly, in blood of patients with prolonged severe sepsis, TNFalpha was reduced by 67.2% (P < 0.0001) and IL-6 was reduced by 32.9% (P < 0.0001); IL-1beta and IL-10 were not modulated by catecholamines in these patients. In blood samples of patients in prolonged septic shock, epinephrine did not modulate cytokine levels of IL-6 and IL-10, and decreased TNFalpha only by 36.4% (P < 0.0001). Interestingly, epinephrine suppressed the IL-1beta production by 73% (P < 0.0001) in blood of patients in prolonged septic shock, which was twice as much as in blood samples of healthy volunteers. The altered response of septic blood to catecholamines might be due to an altered reactivity of leukocytes in the prolonged disease although an additional role of preexisting catecholamines cannot be completely excluded.