Interferon-γ release assays
are medical tests used in the diagnosis of some infectious diseases, especially tuberculosis
. Interferon-γ release assays rely on the fact that T-lymphocytes will release interferon-γ when exposed to specific antigens. These tests are mostly developed for the field of tuberculosis diagnosis
, but in theory, may be used in the diagnosis of other diseases which rely on cell-mediated immunity, e.g. cytomegalovirus
. For example, in patients with cutaneous adverse drug reactions
, challenge of peripheral blood lymphocytes with the drug causing the reaction produced a positive test result for half of the drugs tested.
There are currently two interferon-γ release assays available for the diagnosis of tuberculosis:
The former test quantitates the amount of gamma interferon produced in response to the ESAT-6 and CFP-10 antigen from Mycobacterium tuberculosis, which are distinguishable from those present in BCG and most other non-tuberculous mycobacteria. The latter test determines the total number of individual effector T cells expressing gamma interferon.
The indications for the test are still disputed. It has been evaluated for the diagnosis of latent tuberculosis in HIV patients (who frequently have a negative Mantoux test).