title: Healthy individuals that control a latent infection with Mycobacterium tuberculosis express high levels of Th1 cytokines and the IL-4 antagonist IL-4delta2.
abstract: The majority of healthy individuals exposed to Mycobacterium tuberculosis will not develop disease and identifying what constitutes "protective immunity" is one of the holy grails of M. tuberculosis immunology. It is known that IFN-gamma is essential for protection, but it is also apparent that IFN-gamma levels alone do not explain the immunity/susceptibility dichotomy. The controversy regarding correlates of immunity persists because identifying infected but healthy individuals (those who are immune) has been problematic. We have therefore used recognition of the M. tuberculosis virulence factor early secretory antigenic target 6 to identify healthy, but infected individuals from tuberculosis (TB)-endemic and nonendemic regions (Ethiopia and Denmark) and have compared signals for cytokines expressed directly ex vivo with the pattern found in TB patients. We find that TB patients are characterized by decreased levels of Th1 cytokines and increased levels of IL-10 compared with the healthy infected and noninfected community controls. Interestingly, the healthy infected subjects exhibited a selective increase of message for the IL-4 antagonist, IL-4delta2, compared with both TB patients or noninfected individuals. These data suggest that long-term control of M. tuberculosis infection is associated not just with elevated Th1 responses but also with inhibition of the Th2 response.
authors.affiliation: Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
authors.forename: Abebech
authors.initials: A
authors.lastname: Demissie
authors.forename: Markos
authors.initials: M
authors.lastname: Abebe
authors.forename: Abraham
authors.initials: A
authors.lastname: Aseffa
authors.forename: Graham
authors.initials: G
authors.lastname: Rook
authors.forename: Helen
authors.initials: H
authors.lastname: Fletcher
authors.forename: Alimuddin
authors.initials: A
authors.lastname: Zumla
authors.forename: Karin
authors.initials: K
authors.lastname: Weldingh
authors.forename: Inger
authors.initials: I
authors.lastname: Brock
authors.forename: Peter
authors.initials: P
authors.lastname: Andersen
authors.forename: T Mark
authors.initials: TM
authors.lastname: Doherty
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000032:analysis; D001426:Bacterial Proteins; D016207:Cytokines / Q000096:biosynthesis*; D006801:Humans; D015847:Interleukin-4 / Q000037:antagonists & inhibitors*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D016207:Cytokines; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D015847:Interleukin-4