Role of interleukin-2 (IL-2) in cancer-related immune deficiency: in vitro response to IL-2, production of IL-2, and IL-2 receptor expression in patients with advanced cancer.

The aims of the investigation were 1) to determine if there are defects in interleukin-2 (IL-2) regulation on either phytohemagglutinin (PHA)-activated or non-PHA-activated peripheral blood mononuclear cells (PBMC) in cancer patients to ascertain the role of IL-2 in this disease; 2) to carry out preliminary experiments for a direct quantitative evaluation of endogenous IL-2 production by PBMC cultures; and 3) to evaluate the IL-2 receptor expression by PBMC of cancer patients. An assessment of lymphocyte subsets was also performed with monoclonal antibodies in a selected group of patients. A total of 170 patients entered the study. Cancer sites were larynx (48), breast (44), lung (30), colorectal(23), and gynecologic (25). Staging showed in the former three cancer sites predominantly localized or only locally advanced disease and in the latter two sites disseminated disease. PBMC cultures were performed with microtiter plate technique and 3H-thymidine uptake evaluation using polyclonal mitogens, IL-2, and a monoclonal antibody against IL-2 receptor. Our results provided evidence that the cancer patients exhibit a T-cell functional immunodepression, which, to some extent, progresses during tumor growth so that the localized disease shows a low-grade defect and advanced disease a high-grade defect. Our data also clearly suggest that IL-2 deficiency is the primary factor involved in this functional immune impairment. We found no significant defect in the IL-2 receptor expression by PBMC of cancer patients. Our data also seem to support the in vivo therapeutic administration of IL-2 and lymphokine-activated killer cells to cancer patients.