Abnormal production of transforming growth factor β and interferon γ by peripheral blood cells of patients with multidrug-resistant pulmonary tuberculosis in Brazil

Objectives. The aim of the present study was to determine the immune response profile that differentiates patients with newly diagnosed (non-treated) pulmonary tuberculosis from multidrug-resistant (MDR) ones, as well as from healthy, tuberculin positive individuals. Methods. Lymphocytes proliferative response to non-specific mitogen (PHA) and PPD were evaluated by H-3 thymidine incorporation and cytokines were quantified using an ELISA assay. Results. Patients with active disease showed a diminished proliferative response to PHA and PPD, white multidrug-resistant patients showed a diminished proliferative response to PHA, but a normal response to PPD. The cytokine production of newly diagnosed patients was characterized by a diminished production of IFN gamma and normal production of transforming growth factor (TGF beta), while MDR patients revealed a normal production of IFN gamma accompanied by an increase in TGF beta. Conclusions. The production of significant amounts of TGF beta in MDR patients leads to a poor immune response and may contribute to the resistance of tuberculosis patients to drugs. (C) 2005 The British Infection Society. Published by Elsevier Ltd. All rights reserved.