Frequencies of region of difference 1 antigen-specific but not purified protein derivative-specific gamma interferon-secreting T cells correlate with the presence of tuberculosis disease but do not distinguish recent from remote latent infections.

The majority of individuals infected with Mycobacterium tuberculosis achieve lifelong immune containment of the bacillus. What constitutes this effective host immune response is poorly understood. We compared the frequencies of gamma interferon (IFN-gamma)-secreting T cells specific for five region of difference 1 (RD1)-encoded antigens and one DosR-encoded antigen in 205 individuals either with active disease (n = 167), whose immune responses had failed to contain the bacillus, or with remotely acquired latent infection (n = 38), who had successfully achieved immune control, and a further 149 individuals with recently acquired asymptomatic infection.

Improved diagnostic evaluation of suspected tuberculosis.

Background: The role of new T-cell-based blood tests for tuberculosis in the diagnosis of active tuberculosis is unclear.

Objective: To compare the performance of 2 interferon-gamma assays and tuberculin skin testing in adults with suspected tuberculosis.

Design: Prospective study conducted in routine practice.