A novel MTB-specific IL2 release assay for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Results from a large outbreak study

Background: Transmission of Mycobacterium tuberculosis (MTB) depends on the intensity of MTB exposure, the immune status of the host and mycobacterial virulence. Methods: We present the results of a tuberculosis contact investigation of a highly symptomatic sputum smear positive index case with pulmonary tuberculosis among a large group of well-defined asymptomatic close contacts. Immunological investigations included a tuberculin skin tests (TST) and early secretory antigenic target (ESAT)-6/culture filtrate protein (CFP)-10 specific ELISPOT with IFN-γ and a novel ESAT-6/CFP-10 specific IL-2 ELISPOT. Results: O…