H. Iwagaki et al., DECREASED SERUM TRYPTOPHAN IN PATIENTS WITH CANCER CACHEXIA CORRELATES WITH INCREASED SERUM NEOPTERIN, Immunological investigations, 24(3), 1995, pp. 467-478
We investigated serum tryptophan (Trp), neopterin (NPT) and immunosupp
ressive acidic protein (IAP), one of tumor-associated tumor marker, co
ncentrations in 28 patients with gastrointestinal tumors representing
cancer cachexia and 10 healthy controls. NPT comes from activated macr
ophages presumably activated by tumor-sensitized T cells via gamma-int
erfron (IFN-gamma) excitation of the macrophages. We found that the NP
T level was significantly higher than the control value. The negative
correlation of NPT and tip concentrations indicates activity of indole
amine 2,3-dioxygenase(IDO), a Trp degradating enzyme, in cancer-burden
patients. The activity of IDO can be induced by cytokines such as IFN
-gamma, and therefore low Trp levels may, result from endogenous IFN-g
amma production due to immune activation against tumors. We also found
a positive correlation between NPT and IAP levels, suggesting that ho
st immune activation against tumors played a role in the immunosuppres
sion of cancer-burden states, followed by cancer-cachexia.