Elevation in interleukin 13 levels in patients diagnosed with systemic inflammatory response syndrome

Objective: To examine plasma levels and circadian rhythm of interleukin 13 (IL-13), tumour necrosis factor (TNF) α and total serum cortisol in the systemic inflammatory response syndrome (SIRS). Design and setting: Prospective observational study in a 12-bed medical-surgical ICU of a 500-bed university hospital. Patients: Ten patients with SIRS and eight controls. Measurements: Arterial blood was sampled hourly for 24 h for measurement of plasma IL-13, TNF- α, cortisol and white blood cell count (WCC) differential within 24 h of development of SIRS. Results: There were significantly higher plasma IL-13 levels in SIRS patients than in controls (1282 vs. 713 pg/ml). IL-13 was significantly higher in patients with a diagnosis of sepsis than in those with non-infectious causes of SIRS (2080 vs. 515 pg/ml). In SIRS the elevation in IL-13 was associated with higher TNF-α and reduced WCC. A circadian rhythm was observed in plasma IL-13 secretion. No distinct circadian rhythm was noted for TNF- α, and the normal circadian rhythm of serum cortisol was lost. Conclusions: The anti-inflammatory cytokine IL-13 is elevated in early SIRS. Its plasma level exhibits a circadian rhythm and may be modulated in part by TNF-α. SIRS patients have disruption of the normal circadian rhythm of serum cortisol.