Interleukin-4 blood concentrations in early and metastatic human solid neoplasms

Blood levels of the immunosuppressive cytokines IL-6 and IL-10 are often abnormally high in patients with advanced cancer. However, since IL-6 and IL-10 may be produced by macrophages and TH2 cells, the evidence of abnormally high values of IL-6 and/or IL-10 may reflect hyperactivation either of the macrophage system or of TH2 cell functions. In contrast, IL-4 is almost completely produced by the TH2 lymphocytes. Therefore, evaluation of IL-4 levels could help to differentiate macrophage from TH2 cell hyperactivation. This study was performed to investigate IL-4 serum levels in a group of cancer patients in relation to the stage of disease and to the secretion of other cytokines. The study included 50 patients, 28 of whom showed distant organ metastases. Lung cancer and gastrointestinal cancers were the most frequent neoplasms in our patients. The control group consisted of 60 healthy subjects. IL-4 was measured by the Elisa method. No patient showed high levels of IL-4. No significant differences were seen between controls and cancer patients, nor between metastatic and non-metastatic patients. In addition, no significant differences in IL-4 mean values were found between patients with normal or high levels of IL-6 and IL-10, or between patients with normal or low IL-2 concentrations. This preliminary study seems to exclude cancer-related abnormally high secretion of IL-4. Therefore, the high levels of IL-6 and/or IL-10 often occurring in advanced neoplastic disease would mainly depend on macrophage production.