Membrane-bound and Soluble IL-2 Receptors (p55 and P75 Chains) on Peripheral Blood Mononuclear Cells from Patients with Solid Malignancies

The aim of the investigation was to study directly the IL-2 receptor (IL-2R) and its subunits, p55 and p75 chains, either membrane-bound or soluble, on PBMC of patients with solid malignancies and, indirectly, the same patients' PBMC ability to produce IL-2. Fifty-eight cancer patients, 29 men and 29 women, were studied: their mean age was 57.3 yr, range 35-79. Twenty-two healthy age-sex-matched subjects served as controls. The tumors were the most common and the most representative among human cancers, i.e., breast, lung, head and neck, digestive tract and liver, prostate and gynecologic cancers: they were generally in advanced stages and in 23 cases metastatic. The PBMC proliferative response to PHA, PHA plus IL-2, and IL-2 was evaluated along with the response to PHA in the presence of anti-p55, anti-p75 monoclonal antibodies, or both. Moreover, membrane-bound IL-2R (p55 and p75 chains) on PHA-stimulated PBMC was detected, along with soluble IL-2R in the serum and in the culture supernatants. The conclusions suggest that in solid malignancies: the membrane-bound IL-2Rs, both p55 and p75 chains, are expressed normally, there is an high serum level of soluble IL-2R, there is a normal release of soluble IL-2R in culture, and there is an indirect evidence of a lack of IL-2 production. Therefore, no primary impairment of IL-2R was found in solid tumors. Moreover, in our study we have found no difference in any parameter studied between patients with and patients without metastases.