A study of interactions among markers of macrophage functions in metastatic solid tumors: neopterin levels in relation to those of tumor necrosis factor-alpha and of soluble interleukin-2 receptors.

High levels of the macrophage activation marker neopterin have been described in metastatic cancer patients. Since macrophages may either counteract or stimulate tumor development, it is important to establish which macrophage activity is mainly related to neopterin release. The present study was carried out to evaluate neopterin levels in metastatic solid tumor patients in respect with the antitumor macrophage cytokine TNF and with soluble IL-2 receptor (SIL-2R), whose secretion is stimulated by macrophages and it is associated with the immunosuppressive status of cancer patients. The study included 35 patients with metastatic solid neoplasms. Serum levels of neopterin, TNF and SIL-2R were measured in blood samples collected during the morning. Abnormally high concentrations of neopterin were seen in 18/35 (51%) patients. Patients with high levels of neopterin showed significantly higher concentrations of SIL-2R than those with normal neopterin values, whereas no difference was found in TNF levels. This study would suggest that the increased secretion of neopterin may reflect macrophage-mediated immunosuppression in metastatic solid neoplasms, rather than to be associated with the antitumor activity of macrophages.