Clinical immunology
Mediastinal lymphadenectomy causes immunosuppression after lung cancer surgery

The aim of this study was to estimate the amount of surgical injury caused by systematic lymphadenectomy of mediastinum in patients with lung cancer. Twenty-three patients undergoing uncomplicated resection due to lung cancer (11 right lung cancer, 12 left lung cancer) were analyzed. In patients with right lung cancer systematic lymphadenectomy, while in patients with left lung cancer systematic sampling was performed. Serum IL-6 and IL-1ra concentration was 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. Peripheral blood lymphocyte (PBL) count was measured with flow cytometry. Time of surgery was higher in patients after right than after left thoracotomy (154.1±31.29 vs. 119.6±24.81 minutes; P=0.008). The number of resected mediastinal lymph nodes was higher in patients after right than left thoracotomy (27.6±7.6 vs. 11.1±8.1; P=0.00006). Postoperative decrease of PBL was significantly higher in patients after right than left thoracotomy (1.25±0.37 vs. 1.75±0.64×103/µL; p=0.04). No significant differences were found in serum, pleural fluid and sputum concentration of IL-6 and IL-1ra between patients after right and left thoracotomy, but
a negative correlation between concentration of these cytokines in pleural fluid and a number of resected mediastinal lymph nodes was found (Spearman test for IL-6: r=-0.723; P<0.001; for IL-1ra: r=-0.768; P<0.001). Number of “positive” N2 lymph nodes did not correlate with cytokines’ pleural fluid concentration. Systematic lymphadenectomy of the mediastinum causes immunosuppression, measured by decrease of PBL and negative correlation between the number of resected mediastinal lymph nodes and concentration of IL-6 and IL-1ra in pleural fluid on postoperative day 1.