Résumé : Treatment of latent tuberculosis infection (LTBI) in target populations is one of the current WHO strategies to prevent active tuberculosis (TB) and reduce the Mycobacterium tuberculosis (Mtb) reservoir. Powerful LTBI screening tools are therefore indispensable. An interferon-gamma release assay (IGRA) in response to the stimulation of peripheral blood mononuclear cells by the latency antigen Heparin-Binding Haemagglutinin (HBHA-IGRA) has proven its potential. We have evaluated its possible optimization through a reduction of incubation time from 96 to 24 hours with the addition, in compensation, of IL-7. We have also investigated the phenotype of the IFN-γ producing cells after both short and long incubation times. 131 non immuno-compromised patients were recruited from 3 Brussels-based university hospitals. They were divided into subgroups according to their Mtb infection status (LTBI, TB, undetermined Mtb infection status and non-infected controls). The novel 24h-HBHA-IGRA was performed for all subjects and a simultaneous 96h classical HBHA-IGRA for 79 individuals. Results showed a good correlation between the two tests and the novel 24h-HBHA-IGRA maintained the principal advantages of the classical test, namely a high specificity for LTBI diagnosis, absence of interference of BCG vaccination during infancy and a relative discrimination between LTBI and TB. Whereas commercialized IGRA show a greater sensitivity for recent Mtb infections, the 24h-HBHA-IGRA appears to have a comparable diagnostic power for both recent and remote LTBI. The IFN-γ detected by the 24h-HBHA-IGRA was mainly secreted by effector memory CD4(+) T lymphocytes, a finding suggestive of continuous HBHA presentation during latency.