Ex vivo characterization of early secretory antigenic target 6-specific T cells at sites of active disease in pleural tuberculosis

Presence of early secretory antigenic target- 6 ( ESAT- 6) - specific, interferon- g - secreting T cells in blood accurately marks tuberculosis infection. In tuberculous pleural effusions from 10 patients with tuberculosis, these cells were concentrated a mean of 15- fold ( standard deviation, +/- 6- fold), relative to their level in peripheral blood (P = .014), and displayed rapid effector function. Such cells were absent in 8 control patients with nontuberculous pleural disease. The recruitment of ESAT- 6 - specific T cells to inflamed tuberculous tissue demonstrates their function in vivo and suggests a novel way to diagnose tuberculous pleuritis.