Ex Vivo Characterization of Early Secretory Antigenic Target 6-Specific T Cells at Sites of Active Disease in Pleural Tuberculosis

Abstract
Presence of early secretory antigenic target-6 (ESAT-6)—specific, interferon-γ—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.