INCREASE IN SERUM INTERLEUKIN-6, PLASMA ACTH AND SERUM CORTISOL-LEVELS AFTER SYSTEMIC INTERFERON-ALPHA ADMINISTRATION

Systemic administration of human interferon-a stimulates the pituitary -adrenal axis in men, but the exact mechanism still remains to be esta blished. The present study was undertaken to examine the hypothesis th at interferon-a may alter the circulating concentrations of the cytoki nes which involve the activation of the pituitary-adrenal axis. Eleven patients with chronically active hepatitis C were treated with human lymphoblastoid interferon-alpha (IFN: 6 x 10(6) IU/day) and changes in plasma adrenocorticotropin (ACTH), serum cortisol and cytokine concen trations were observed on both the first and second days of the treatm ent. Subcutaneous administration of IFN significantly increased plasma ACTH and serum cortisol concentrations by 3 h after the injection. Se rum interleukin-6 (IL-6) increased with the increase in circulating AC TH and cortisol. There was a significant correlation between serum cor tisol and IL-6 concentrations at 3 h. In contrast, an increase in seru m interleukin-1 beta was only observed in one case. On the second day of IFN treatment, simultaneous administration of 25 mg diclofenac sodi um eliminated the IFN effects on circulating ACTH, cortisol and IL-6 c oncentrations. The present studies demonstrated that circulating IL-6 increases after systemic IFN administration, resulting in activation o f the pituitary-adrenal axis.