There is growing evidence that the pineal gland has antineoplastic properties, which include the action of melatonin (MLT) on the immune system through the release of cytokines by activated T-cells and monocytes. Despite these intriguing preliminary findings, only few studies have been undertaken to date on MLT's action in cancer patients. The present study was carried out on 23 patients (15 males and 8 females, range 48-71 years), with advanced solid tumors, who received MLT (10 mg/day orally for a month) after conventional therapy. Blood was assayed for tumor necrosis factor alpha (TNF-alpha), Interleukin-2 (IL-2) and human interferon gamma (IFN-gamma). Blood samples were taken immediately before the start of MLT administration and 30 days after therapy. Plasma was collected in EDTA tubes on ice, centrifuged immediately at 4-degrees-C and stored frozen at -80-degrees-C until assayed. Cytokines were quantified by immunoradiometric assays. Circulating levels of TNF-alpha, IL-2 and IFN-gamma increased by 28%, 51% and 41% respectively after MLT administration. These increments were statistically significant (paired Student's t-test, p<0.01). These findings are consistent with the hypothesis that MLT modulates immune functions in cancer patients by activating the cytokine system.

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