Analysis of the KYN/TRP ratio for IDO activity in culture supernatants of HFA, AA and glioma determined by HPLC and analysis of plasma Tryptophan (TRP), Kynurenine (KYN), Quinolinic acid (QUIN), Picolinic acid (PIC) and Kynurenic acid (KYNA) concentrations and the Kynurenine (KYN)/Tryptophan (TRP) and KYNA/KYN ratios from normal healthy controls (n = 18) versus GBM patients (n = 18).

The graph and dot plots indicate Log10 of the quantified values unless otherwise shown. Glioma cell cultures were untreated (n = 7) and treated with IFN-γ (n = 6) for 48 hours and untreated (n = 6) and treated (n = 6) with IFN-γ for 72 hours. HFA cell cultures were untreated (n = 10) and treated with IFN-γ (n = 9) for 48 hours and untreated (n = 5) and treated with IFN-γ for 72 hours (n = 5). AA cell cultures were untreated (n = 3) and treated with IFN-γ (n = 3) for 48 hours. IDO activity in HFA cell cultures after 48 and 72 hours of IFN-γ stimulation compared to untreated cultures (^αµp<0.001). IDO activity in AA cell cultures after 48 hours of IFN-γ stimulation compared to untreated cultures (^πp<0.001). IDO activity in gliomas after 48 and 72 hours of IFN-γ stimulation compared to untreated cultures (^γβp<0.05). No other statistical significance was observed. The GBM plasma samples consisted of: recurrent GBM (n = 9), secondary GBM (n = 5), primary GBM (n = 1), PNET GBM (n = 2) and unclassified GBM (n = 1). Each dot represents data derived from 1 sample. Horizontal line in each group designates the mean value. TRP concentrations in GBM patients compared to that of the control group (^αp<0.0001). KYN concentrations in GBM compared to Control (^αp = 0.0005). The KYN/TRP ratio for IDO activity in GBM compared to Control (^αp<0.0001). KYNA concentrations in GBM patients compared to that of the control group (^αp<0.0001). KYNA/KYN ratio in GBM compared to the control group (^αp = 0.001). The GBM plasma samples analysed for QUIN and PIC concentrations consisted of: recurrent GBM (n = 7), secondary GBM (n = 3), PNET GBM (n = 2) and unclassified GBM (n = 1). QUIN concentrations in GBM compared to controls (^αp = 0.0014). PIC concentrations in GBM compared to the control group (^αp<0.0001).