Time-scale of interleukin-6, myeloid related proteins (MRP), C reactive protein (CRP), and endotoxin plasma levels during the postoperative acute phase reaction

During goitre surgery (25 patients) and after major abdominal surgery (52 patients), we studied the plasma levels of endotoxin, interleukin-6 (IL-6), C reactive protein (CRP), and the so called myeloid-related proteins (MRP), MRP8, MRP14, and the heterocomplex of both single proteins, MRP8/MRP14 in three intervals: pre-, intra-, and postoperative. We observed that CRP levels began to increase on the first postoperative day, reaching a maximum on day 2 (median levels of 185 mg/L after major surgery and 77 mg/L after goitre surgery). IL-6 levels peaked at the end of the operation, remaining elevated for 6 h following abdominal surgery (299 pg/mL) and peaked on day 1 after goitre surgery (63 pg/mL). An increase in MRP8/MRP14 levels began toward the end of abdominal surgery, and maximum levels were recorded until 5 days after the operation (5,695 micrograms/L). Plasma levels were significantly elevated 2 and 6 h after minor surgery (3,619 micrograms/L), while no changes were observed in the plasma levels of MRP8 and MRP14. Evidence of significant endotoxemia was found after the induction of anesthesia in the abdominal surgery group (.13 endotoxin units (EU)/mL) and after skin incision (.07 EU/mL) in the thyroid surgery group. The observed time sequence, starting with the release of bacterial products at an early stage, followed by the secondary stimulation of factors inherent to the acute phase led us to conclude that certain bacterial compounds, probably deriving from the gastrointestinal tract, trigger the postoperative acute phase reaction and are responsible for the activation of monocytes/macrophages and granulocytes.