Elevated plasma cortisol levels during interferon-gamma treatment.

We investigated plasma levels of cortisol and ACTH in 9 patients with advanced metastatic tumors before and during treatment with interferon-gamma (IFN-gamma), 2-4 h after administration of IFN-gamma there was a sharp rise in plasma cortisol levels. The rise coincided with the onset of fever. Highest cortisol levels were reached 4-6 h after IFN-gamma injections, whereas IFN-gamma serum levels peaked 6-10 h after the IFN-gamma injections. Elevated cortisol levels during IFN-gamma treatment may be part of a homeostatic response of the neuroendocrine system to the immunological stimulus induced by IFN-gamma. On the other hand, the increased plasma levels of cortisol in response to pharmacological doses of IFN-gamma may dampen the in vivo effectiveness of IFN-gamma.