QFT-Plus works by exposing your blood lymphocytes (immune cells) to highly specific TB antigens (parts of the bacteria that causes TB), which causes the lymphocytes to produce a quantifiable small molecule called Interferon-γ (IFN-γ). Interferon-gamma production is correlated to the presence or absence of TB infection, and this IFN-γ response is measured in a laboratory to aid in the diagnosis of TB infection.
There are three possible QFT-Plus results:
Positive – suggests that TB infection is likely
Negative – suggests that TB infection is unlikely
Indeterminate – suggests the need for further investigations or repeat testing
