Serum levels of interleukin-18 (IL-18) and soluble interleukin-2 Receptor (sIL-2R) in lung cancer
Naumnik W, Chyczewska E, Kovalchuk O, Talalaj J, Iycki T, Panek B

Purpose: We evaluated the clinical usefulness of interleukin-18 (IL-18) and soluble interleukin-2 receptor (sIL-2R) during chemotherapy of lung cancer in relation to the histological type of the tumor, clinical stage, response to therapy and time survival.
Material and methods: Serum levels of IL-18 and sIL-2R were determined in 73 patients (62 males; mean age 64 years; 41 with non-small cell lung cancer-NSCLC, 32 with small cell lung cancer-SCLC); 12 healthy subjects served as controls. To determine IL-18 serum concentrations (Elisa), venous blood samples were collected from each patient before and after chemotherapy. 
Results: The mean serum IL-18 level in all patients with lung cancer was significantly higher compared with healthy volunteers (p=0.0001; NSCLC vs control p=0.0001; SCLC vs control p=0.004). In NSCLC group with stage IV the mean IL-18 level was significantly higher than those with stage IIIB (p=0.04). Regardly to tumor stage as well as in relation to response to therapy, no significant differences in IL-18 were observed. Using cut-off serum IL-18 concentration of 319.6 pg/ml, the prognoses of the two groups were different, but it was not statistically significant. The serum levels of sIL-2R in NSCLC patients were significantly higher than in controls (p=0.018). There were no significant differences in serum sIL-2R levels in relation to clinical stage of lung cancer and response to therapy. The cut-off value between high and low serum sIL-2R concentration was defined as 582.27 U/ml. The difference in survival rate between the high and low sIL-2R groups was not significant.
Conclusions: Serum IL-18 and sIL-2R levels can be useful in clinical practice, but their practical significance needs further studies. 

Keywords:   interleukin-18 (IL-18), soluble interleukin-2 receptor (sIL-2R), small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC), chemotherapy.