Effects of granulocyte-macrophage colony stimulating factor on soluble interleukin-2 receptor serum levels and their relation to neopterin and tumor necrosis factor-alpha in cancer patients.

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.