IL-6 AND SOLUBLE IL-6 RECEPTOR LEVELS CHANGE DIFFERENTLY AFTER SURGERY BOTH IN THE BLOOD AND IN THE OPERATIVE FIELD

To investigate alterations in post-operative levels of IL-6 and solubl e IL-6 receptor (sIL-6R), we examined their levels in serum and sample s of drainage fluids from 26 patients who underwent thoracoabdominal s urgery, Serum IL-6 levels reached the maximum within the first postope rative day and decreased thereafter, The IL-6 levels in the drainage f luid were much higher than in the serum (458 +/- 101-fold; mean +/- SE M) in the early post-operative phase, A large quantity of sIL-6R level s was present in blood samples, The time course of serum sIL-6R levels in 26 patients showed no significant change, sIL-6R concentrations in the drainage fluid were significantly lower than in serum (4.5 +/- 1. 1-fold; mean +/- SEM) in the early post-operative phase. We propose th at IL-6 is produced in the operative field and enters the peripheral b lood stream to induce elevation of serum IL-6, On the other hand, sIL- 6R levels in the operative field are lower than in the serum, and the serum sIL-6R levels are not influenced by surgical trauma, These data suggest that sIL-6R is being constantly produced in areas other than t he operative field, while sIL-6R level is reduced by consumption in th e operative field, Mechanisms to cope with surgical stress, involving sIL-6R together with its ligand IL-6 may thus exist. (C) 1997 Academic Press Limited.