Spontaneous and Inducible Cytokine Responses in Healthy Humans Receiving a Single Dose of IFN-α2b: Increased Production of Interleukin-1 Receptor Antagonist and Suppression of IL-1-Induced IL-8

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Abstract
The present study was to determine whether the administration of a single dose of interferon-alpha2B (IFN-alpha2B) to healthy humans affects endogenous (or basal level) or inducible cytokines in a whole blood, ex vivo culture. Twenty-four healthy volunteers received an s.c. injection of IFN-alpha2b (3 x 10(6)U), and 4 volunteers received the vehicle as placebo. The study was blinded. Blood was drawn before and 3, 6, 12, and 24 h after the injection and incubated in the presence or absence of lipopolysaccharide (LPS) or interleukin-1beta (IL-1beta). After 24 hs, the plasma was assayed for tumor necrosis factor-alpha (TNF-alpha), IFN-gamma, IL-1beta, IL-1 receptor antagonist (IL-1Ra), and IL-8. Treatment with IFN-alpha2b was associated with a 4.8-fold increase in the endogenous production of IL-1Ra in cultured blood sustained over 24 hs. In contrast, no change in endogenous IL-1Ra production was detected in the controls. A significant suppression (75%, p < 0.001) of IL-1beta-induced IL-8 production 3 and 6 h after IFN-alpha2b compared with control subjects was observed. These effects were also observed when IFN-alpha2b was added directly to whole blood cultures in vitro. In contrast to IL-1 stimulation, LPS stimulation of blood from IFN-alpha2b-treated subjects resulted in enhanced IL-1beta and TNF-alpha production. These results suggest that a single dose of IFN-alpha2b induces an anti-inflammatory state for endogenous stimuli but a proinflammatory state for exogenous endotoxin.