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SIL-2R levels mainly depend on a T lymphocyte production. The mechanisms responsible for the elevated blood concentrations of SIL-2R in advanced solid tumors are still unknown. To investigate the role played by the monocyte-macrophage system on SIL-2R release, we have evaluated serum levels of SIL-2R in 10 head and neck cancer patients during GM-CSF subcutaneous administration (3 mcg/kg/day for 11 consecutive days). Serum levels of TNF and neopterin, both produced by macrophages, were also measured. SIL-2R mean concentration significantly enhanced in response to GM-CSF, and their rise positively correlated to that in TNF and neopterin values, while lymphocyte mean number did not increase during the study. The present results represent the first in vivo demonstration that SIL-2R release is related to macrophage activation, rather than to depend only on lymphocyte proliferation.

TNF, in addition to its antitumor activity, would play an important role in the pathogenesis of cancer-related severe complications, including ARDS and DIC. Therefore, the modulation of TNF secretion could be important in the supportive care of advanced cancer patients. At present, PTX is the only drug which has been proven to be able to inhibit in vitro the release of TNF. The present study was performed to evaluate the effect of PTX on TNF blood concentrations in disseminated cancer patients with abnormally high TNF values. The study included 14 cancer patients, with initial or conclamate signs of ARDS (n = 8) or DIC (n = 6). PTX was given intravenously at a dose of 300 mg/day for 7 days. Mean serum levels of TNF significantly decreased in response to PTX therapy, and they returned to normal range in 5/14 patients. These preliminary data would suggest that PTX may be considered as a biological response modifier, capable of inhibiting TNF secretion in humans, with a following potential use in the treatment of cancer-related severe complications.

TNF, a cytokine produced by macrophages, is able either to exert an antitumor activity, or to determine severe clinical complications, such as cachexia and septic shock. Increased blood levels of TNF have been described in cancer patients. The present study was performed to better define TNF secretion in patients with solid tumors. The study included 48 cancer patients (lung cancer: 22; colon cancer: 11; breast cancer: 10; renal cancer: 5), and among them 27 showed distant organ metastases. TNF serum levels were measured by IRMA method. The control group comprised 40 healthy subjects. TNF levels were also evaluated in relation to those of SIL-2R, whose increase seems to be associated with an unfavorable prognosis in cancer. High levels of TNF were seen in 27/48 (56%) patients. Mean levels of TNF were significantly higher in cancer patients than in controls. Moreover, within the cancer group, TNF mean values were significantly higher in metastatic patients than in those without metastases; the highest levels were observed in patients with visceral lesions as dominant metastasis sites. Finally, patients with high TNF concentrations showed significantly higher mean levels of SIL-2R than those with normal values. This study shows that the neoplastic metastatic disease is associated with an exaggerated TNF secretion.