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 mechanis ms responsible for the elevated blood concentrations of SIL-2R in adva nced solid tumors are still unknown. To investigate the role played by the monocyte-macrophage system on SIL-2R release, we have evaluated s erum levels of SIL-2R in 10 head and neck cancer patients during GM-CS F 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 res ponse to GM-CSF, and their rise positively correlated to that in TNF a nd neopterin values, while lymphocyte mean number did not increase dur ing the study. The present results represent the first in vivo demonst ration that SIL-2R release is related to macrophage activation, rather than to depend only on lymphocyte proliferation.