The effects of noradrenaline and alpha-2 adrenoceptor agents on the production of monocytic products.

There are some reports that catecholamines may modulate the production of monocytic cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF alpha). The present study was carried out in order to examine the effects of noradrenaline (10(-5), 10(-6) and 10(-7) M), clonidine (10(-5), 10(-6) and 10(-7) M), an alpha2-adrenoceptor agonist, and yohimbine (10(-5), 10(-6) and 10(-7) M), an alpha 2-adrenoceptor antagonist, on the production of IL-6, the IL-1 receptor antagonist (IL-1RA) and TNF alpha by stimulated whole blood of normal humans. We measured the in vitro production of IL-6, TNF alpha and IL-1RA by stimulated (phytohemagglutinin+lipopolysaccharide), diluted whole blood of 16 normal volunteers. The results show that noradrenaline, 10(-5) M, significantly suppressed the production of IL-6; noradrenaline, 10(-5) and 10(-6) M, significantly suppressed the production of IL-1RA and TNF alpha; clonidine, 10(-5) M, significantly suppressed the production of TNF alpha; and yohimbine, 10(-5) and 10(-6) M, significantly suppressed the production of IL-1RA. It is concluded that (1) noradrenaline has significant negative immunoregulatory effects in humans through suppression of the production of (monocytic) proinflammatory cytokines, e.g. IL-6 and TNF alpha, and (2) the suppression of the production of TNF alpha may be related to alpha(2)-adrenoceptor-related mechanisms.