Correlation between IL-12 and IL-2 blood levels in the metastatic neoplastic disease: a possible inhibitory feedback system regulating their secretion.

Despite the great importance of IL-2 and IL-12 in activating the anticancer immune response in humans, cancer-related physiopathology of their secretion needs to be better investigated. IL-2 blood levels have been proven to decrease in the advanced neoplastic disease, whereas preliminary data would suggest an enhanced secretion of IL-12 in metastatic cancer patients. This study was performed to analyze IL-2 levels in relation to those of IL-12 in metastatic solid neoplasms. The study included 40 untreated metastatic cancer patients. Serum levels of both IL-2 and IL-12 were measured by ELISA. Abnormally low blood levels of IL-2 and elevated values of IL-12 were observed in 16/40 and in 18/40 patients, respectively. Moreover, patients with IL-2 deficiency showed significantly higher mean levels of IL-12 than patients with normal values of IL-2. This preliminary result, by showing an increased secretion of IL-12 in advanced cancer patients with IL-2 endogenous deficiency, would suggest the existance of a possible feedback mechanism operating between macrophage release of IL-12 and T lymphocyte secretion of IL-2.