Increased level of soluble interleukin-2 receptor in advanced solid tumors: a preliminary study

Both activated normal and transformed lymphocytes produce not only cell-associated but also cell-free IL-2R. Evidence of high serum concentrations of IL-2R appears to serve as a tumor marker in patients with lymphomas On the contrary, the role of soluble IL-2R in solid neoplasms has still to be defined. This investigation was carried out to analyze soluble IL-2R production in human solid tumors. The study included 35 patients with solid tumors (12 without and 23 with metastases), 58 healthy subjects and 6 lymphoma patients. Among cancer patients, lung and breast carcinoma were the two most frequent neoplasms. In each subject or patient, serum levels of IL-2R were measured by using an enzyme immunoassay. Moreover, in 14/23 patients with metastatic solid tumors, lymphocyte subpopulations were also evaluated. Serum levels of IL-2R were significantly higher in the cancer patients than in the normal subjects. The patients with metastatic solid tumors showed significantly higher mean levels than those without metastases, and similar to those observed in the lymphoma patients. Finally, there was no correlation between serum levels of IL-2R and the T4/T8 ratio, which was reduced in 5/14 cancer patients. Further studies will be needed to establish if elevated concentrations of IL-2R in the serum can contribute to the immunoincompetence of patients with disseminated solid neoplasms.