..unusual IFN-γ measurements such as HNC, LMR, VLMR, and VLAR were encountered in a small number of QFT-G and QFT-GIT, and in most cases, such measurements were not seen on simultaneously or subsequently performed tests. To avoid erroneous diagnosis of Mtb infection, QFT-G and QFT-GIT with unusual IFN-γ measurements should be repeated with another blood sample and interpreted with caution if they recur.
1) High Nil Concentration (HNC) when IFN-γ concentration in plasma from unstimulated blood exceeded 0.7 IU/mL;
2) Low Mitogen Response (LMR) when Mitogen Response was <0.5 IU/mL;
3) Very Low Mitogen Response (VLMR) when Mitogen Response was ≤−0.5 IU/mL; and
4) Very Low Antigen Response (VLAR) when the response to a Mtb antigen was ≤−0.35 IU/mL and ≤−0.5 times the IFN-γ concentration in plasma from unstimulated blood.
