Flow-cytometric assessment of lymphocyte cytokine production in tuberculosis.

We assessed by flow-cytometry the Th1/Th2 profiles in peripheral blood lymphocytes (PBL) from patients with active tuberculosis (TB), before and after antituberculous therapy, and from healthy tuberculin-positive and -negative reactors. PBL from patients showed a reduced potential for Th1-cytokine (notably IFN- gamma) production after culture with a policlonal stimulus. When these PBL from patients were cultured with a M. tuberculosis (MTB)-specific antigen such as PPD (10 microg/ml), there was no detectable production of Th1 cytokines. Only the Th2 cytokine IL10 was detected in PBL from patients but not from controls. However, at the site of the tuberculosis disease, T lymphocytes from bronchoalveolar lavage, after culture with PPD, produced IFN- gamma. After completion of tuberculosis therapy, PBL did not produce IL10. These data indicate that the immunosuppression observed in PBL during active tuberculosis infection may be related to IL10 production, and to the compartmentalization of the antigen-Th1 response to sites of active MTB infection.