Tuberculosis-specific T-cell response after recent treatment and remote cure

Abstract

To the Editors: Tuberculosis (TB) remains a major global health problem. A major factor contributing to the current TB epidemic is the resistance of Mycobaterium tuberculosis to first-line anti-TB treatment. Therefore, there is a need for an appropriate and reliable tool to evaluate treatment efficacy. Several studies using the T-SPOT®. TB assay (Oxford Immunotec Ltd, Oxford, UK) reported a decline in the number of spots after successful anti-TB treatment, particularly in the 6-kDa early secretory antigenic target (ESAT-6) panel [1–3]; however, to our knowledge, no data have been published on cured TB patients who contracted TB before isoniazid and rifampicin became available. Therefore, the naturally long-term range of ESAT-6- and culture filtrate protein (CFP)-10-specific T-cell responses in patients with TB who did not receive modern anti-TB treatment is not known. Because most patients in prior studies were born in high-burden, TB-endemic countries, the T-cell kinetics might be influenced by reinfection. Therefore, the aim of this report is to compare the ESAT-6- and CFP-10-specific T-cell responses in a low-burden country with a low risk of reinfection between patients with a history of active TB before 1955, and patients with recently treated active TB. Venous blood for T-SPOT®. TB was collected from 24 outpatient subjects with a history of active TB before 1955 (group 1), obtained by clinical history-taking, patients’ medical records or documentation of a sanatorium admission. 16 of these patients had been admitted to a sanatorium, two patients underwent surgery and six patients were treated at home with para-aminosalicylic acid therapy or bedrest. Furthermore, 27 patients with recent active TB (group 2) were prospectively enrolled between March and May 2008. Active TB was defined as fulfilling one or more of the following criteria: 1) positive culture for M. tuberculosis (n=22); 2) positive PCR for M. …