Abstract
In addition to the better known cytokines IL-2 and IL-12, IL-15, which is mainly produced by macrophages, is a new antitumor cytokine with a mechanism of action similar to that of IL-2. At present, however, there are no data about IL-15 secretion in cancer patients. This study was carried out to evaluate IL-15 blood concentrations in patients with early or advanced cancer and their possible variations in response to IL-2 cancer immunotherapy. The study included 40 patients with solid tumors, 24 of whom had metastatic disease. In addition, IL-15 secretion was evaluated during subcutaneous low-dose IL-2 therapy (6 million IU/day for 6 days/week for 4 weeks) in 14 metastatic renal cell cancer patients by collecting blood samples at weekly intervals. The control group consisted of 40 age-matched healthy subjects. Serum levels of IL-15 were measured by an enzyme immunoassay. No significant difference in mean serum levels of IL-15 was observed between cancer patients and controls. Moreover, the mean serum levels of IL-15 found in metastatic cancer patients were not significantly different from those found in patients with limited disease. Finally, no significant changes in mean levels of IL-15 occurred during IL-2 cancer immunotherapy. This preliminary study would suggest that IL-15 secretion is substantially within the normal range in cancer patients, both in early and advanced disease, and no variation seems to occur in response to IL-2 administration.
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