Clinical immunology
Concentrations of interleukin 6 and interleukin 1 receptor antagonist in pleural fluid as early markers of complications after lung cancer surgery

The objectives of the study was to assess value of Interleukin 6 (IL-6) and Interleukin 1 receptor antagonist (IL-1ra) serum, sputum and drained fluid concentrations as markers of complications in patients operated on due to lung cancer. Thirty-eight patients (15 with, 23 without complications) with resectable lung cancer were analyzed. Serum IL-6 and IL-1ra concentrations were measured before and after surgery, and on postoperative day 1, 3, and 7, as well as in sputum at the end of surgery and in pleural fluid on postoperative day 1, by ELISA test. In serum, concentrations of IL-6 and IL-1ra were significantly elevated after surgery in all patients but no differences between two groups were found. Patients with complications had higher concentrations of IL-6 in pleural fluid (90048 (33490-94768) vs. 6554.4 (2003-20636) pg/mL; P=0.00006) and in sputum (3509.4 (2434-14168) vs. 367.6 (245.8-1096) pg/mL, P=0.02). Patients with complications had higher concentrations of IL-1ra in pleural fluid (67908 (52638-106694) vs. 16950 (16050-45470) pg/mL; P=0.00007) and in sputum (80109 (52289-212459) vs. 11816.3 (5854-30511.9) pg/mL, P=0.02). On day 1 after surgery a positive correlation between serum and pleural fluid concentration of IL-6 and IL-1ra were observed (Spearman test for IL-6: r=0.47; p=0.02; for IL-1ra: r=0.48; p=0.02) Logistic regression analysis showed that increase of concentration of IL-6 and IL-1ra in pleural fluid increases the risk of complications (P=0.0008 and P=0.03, respectively). Results of multivariate analysis confirmed that concentrations of IL-6 and IL-1ra in pleural fluid on postoperative day 1 are independent risk factors of development of postoperative complications (for IL-6: OR=1.029; CI=1.002-1.058; P=0.036; for IL-1ra: OR=1.024; CI=1.000-1.049; P=0.046). Elevated concentrations of IL-6 and IL-1ra in pleural fluid on postoperative day 1 are promising early markers of postoperative complications in lung cancer surgery.