Principle
The LIOFeron®TB/LTBI is a cytokine release assay based on the fact that cells from human blood will secrete IFN-γ when exposed to special M. tuberculosis antigens. LIOFeron®TB/LTBI is a 2 component kit consisting of HUMAN BLOOD STIMULATION TUBES (component 01) and HUMAN IFN-γ ELISA (component 02) The HUMAN BLOOD STIMULATION TUBES contain a positive control tube, a negative control tube and TB antigen tubes for each patient. The human blood sample (heparinized) is taken from the patient by venipuncture and 1 mL each is pipetted into negative-, positive- and TB antigen tubes. The tubes are gently mixed by shaking upside down and placed into a 37°C incubator overnight. Next the clear supernatant (human plasma) is carefully removed and analyzed using HUMAN IFN-γ ELISA which quantitates the amount of IFN-γ produced in response to the antigens from M. tuberculosis. These special antigens are distinguishable from those present in BCG and most other non‑tuberculous mycobacteria.