[In vitro measurement of whole blood gamma interferon as a diagnostic tool in primary ocular tuberculosis]

Tuberculosis (infection by Mycobacterium tuberculosis) remains a public health problem with increasing incidence. The diagnosis of primary ocular tuberculosis is troublesome because of the low sensitivity and poor specifity of routine diagnostic methods and the problems obtaining reliable samples. We report the cases of two patients, one immunocompromised male and one immunocompetent male, presenting chorioretinitis with high clinical suspicion of ocular tuberculosis. We performed serologies, polymerase chain reaction tests in aqueous humor, a purified protein derivative skin test, and measurement of interferon-gamma in whole blood using the QuantiFERON-TB Gold assay. The QuantiFERON-TB Gold assay was positive in both cases, in agreement with the diagnosis of ocular tuberculosis. The purified protein derivative skin test was positive in one case. The whole blood interferon-gamma assay is a precious tool for detecting extrapulmonary tuberculosis, especially in cases of primary ocular disease.