Local IFN- responses in TB

Globally, the tuberculin skin test (TST), smear microscopy, and culture remain central to the diagnosis of tuberculosis (TB) because of the cost and ease of performance. However, TST has poor specificity and reduced sensitivity in settings including HIV and advanced TB,1 smear microscopy lacks sensitivity, and TB culture (the diagnostic gold standard) takes weeks and is positive in only two thirds of treated cases.2 TB pleuritis and peritonitis can be particularly difficult to diagnose due to paucity of bacilli and often need invasive or open procedures. In this setting, assays measuring interferon γ (IFN-γ) production by lymphocytes in response to TB antigens may be useful. While most studies have used blood based assays, more clinically relevant information may exist in local fluids such as bronchoalveolar lavage (BAL) fluid and pleural fluid in which much higher responses have been achieved.3–5 We investigated a 32 year old Somali man, resident in Britain for 2 years, who presented with a 3 week history of vomiting, diarrhoea, anorexia, and abdominal pain. …