The release of interleukin-1 beta (IL-1) precedes that of interleukin 6 (IL-6) in patients undergoing major surgery.

The cytokine response to major surgical trauma has been studied in six patients undergoing elective aortic surgery. Peripheral blood was sampled frequently before, during, and after surgery and the plasma cytokines interleukin-1, interleukin-6, tumor necrosis factor-alpha, and interferon-gamma were measured using enzyme-linked immunosorbent assays. These results were reviewed together with the operative details, clinical course, and C-reactive protein levels. Tumor necrosis factor-alpha and interferon-gamma were not detected in these patients. An early and short-lived interleukin-1 beta response to major surgery was detected only by intensively sampling the intraoperative period. This was a consistent finding that preceded the rise in interleukin-6. Interleukin-6 rose steeply from 2 h, peaking between 4 and 24 h. It had fallen sharply by 48-72 h in five patients who had an uneventful postoperative course. It remained high in one patient who developed complications and fell only when a severe septicemia was treated successfully. His interleukin-6 levels were considerably higher than the other patients even during the operation itself. There was no obvious relation between the interleukin-6 peak and the duration of operation. A sequential interleukin-1 beta and interleukin-6 response has not been noted before in vivo, and would seem to provide evidence supporting the in vitro observation that interleukin-1 induces interleukin-6 synthesis and release. It also provides evidence of an important role for interleukin-6 in the body's response to injury. A larger study is in progress.