THE PLASMA INTERLEUKIN-6 AND STRESS HORMONE RESPONSES TO ACUTE PYELONEPHRITIS

The relationships between the ''stress hormones'' corticotrophin (ACTH ), vasopressin (AVP), corticotrophin releasing hormone (CRH) and corti sol, and the cytokines, interleukin-1 (IL-1), interleukin-6 (IL-6), an d tumor necrosis factor were studied during an acute infection. Ten pa tients (7 female, 3 male, age range 16-56 years) with acute pyelonephr itis and normal renal function were studied during the first 72 hours following hospital admission. Peptide hormones were measured by radioi mmunoassay, cortisol and cytokines by ELISA. Reference ranges for all hormones were from samples donated by 40 or more volunteers from the e lectoral roll. The reference data for IL-6 was obtained from 20 normal donor sera. The mean plasma IL-6, AVP and CRH concentrations on admis sion to hospital were significantly raised above the mean 08:00h value s of the normal volunteers (p<0.001 for AVP and CRH, p<0.01 for IL-6), but mean plasma ACTH and cortisol were not. Mean plasma IL-6 and AVP were raised more than two standard deviations above the mean of the re ference range for 72 hours, although IL-6 tended to fall after 24 hour s. No change in plasma IL-1 and tumour necrosis factor was observed in three patients. The correlation between plasma IL-6 and cortisol conc entrations at all sampling times and in all subjects was highly signif icant (p<0.001). Significant correlations between plasma IL-6 and AVP (p<0.005), and IL-6 and ACTH (p<0.05) were also observed. No correlati on between IL-6 and CRH could be demonstrated. It was concluded that m ean plasma levels of IL-6, AVP and CRH were significantly raised in pa tients with severe acute pyelonephritis on admission to hospital. Plas ma concentrations of IL-6 correlated well with the ''stress hormones'' cortisol, ACTH and AVP, but not CRH. Although IL-6 may contribute to activation of the hypothalamic-pituitary-adrenal (HPA) axis during inf ection, this relationship requires further investigation.