Correlation of serum interleukin-2 levels, soluble interleukin-2 receptors and T lymphocyte subsets in cancer patients.

An interleukin-2 (IL-2) in vitro reduced production has been observed in most metastatic cancer patients. At present, however, there are no data on blood IL-2 levels in vivo, because of the too low sensitivity of previous biological and enzyme immunoassay methods. The recent development of a sensitive RIA method allowed us to start a preliminary investigation of IL-2 production in basal conditions in human solid tumors. The study included 42 cancer patients. Breast and lung cancer were the two commonest neoplasms. Serum levels of IL-2 and soluble IL-2 receptors (SIL-2R), and CD4/CD8 ratio were measured in each patient. The control group consisted of 58 healthy subjects. Mean serum levels of IL-2 were significantly lower in metastatic patients (n = 23) than in those without metastases (n = 19). Patients with low CD4/CD8 ratio (n = 16) had significantly lower mean values of IL-2 than those with normal ratio (n = 26). Finally, mean IL-2 concentrations were significantly lower in patients with elevated levels of SIL-2R than in those with normal values. These results would suggest that metastatic dissemination is associated with a decreased IL-2 production in vivo, and that reduced IL-2 production is more frequent in patients with low CD4/CD8 ratio.