title: Evaluation of an in vitro assay for gamma interferon production in response to Mycobacterium tuberculosis infections.
abstract: The tuberculin skin test (TST) is the "gold standard" for detecting infection with Mycobacterium tuberculosis. We compared the TST using purified protein derivative to the QuantiFERON-TB test (QFT). Two groups were examined. Group 1 individuals (n = 66) (low risk) were at low risk for exposure to M. tuberculosis and were not Mycobacterium bovis BCG vaccinated. Group 2 (n = 29) include individuals who were likely to have been exposed to a high prevalence of M. tuberculosis infections and were BCG vaccinated. Group 1 individuals were given a TST. Group 2 individuals were not given a TST because of possible adverse reactions. A 10- to 15-mm indurated area 48 h after TST was considered positive. A positive QFT result was defined as a significant gamma interferon response to M. tuberculosis antigen, Mycobacterium avium antigen, and a nonspecific mitogen stimulus and no response in the negative control. In group 1, 60 of 66 individuals (90.9%) were negative by both methods, and 1 person was positive by both methods. There was one QFT-negative, TST-positive case, one QFT-positive, TST-negative case, and three conditional QFT-positive, TST-negative cases. In group 2, 12 of 29 (41.4%) were positive by QFT and considered likely to be TST positive because of prior BCG vaccination. QFT testing in our low-risk group resulted in an agreement of 96.8%, a sensitivity of 50%, and a specificity of 98.4% compared with TST results. QFT testing with TST in low-risk groups can aid in the detection of latent M. tuberculosis infections.
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA. taggarew@aruplab.com
authors.forename: Edward W
authors.initials: EW
authors.lastname: Taggart
authors.forename: Harry R
authors.initials: HR
authors.lastname: Hill
authors.forename: Roland G
authors.initials: RG
authors.lastname: Ruegner
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Martins
authors.forename: Christine M
authors.initials: CM
authors.lastname: Litwin
mesh_terms: D000328:Adult; D001500:BCG Vaccine / Q000276:immunology; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009163:Mycobacterium bovis / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011237:Predictive Value of Tests; D013601:T-Lymphocytes / Q000276:immunology*; D014373:Tuberculin / Q000276:immunology*; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis / Q000276:immunology* / Q000517:prevention & control
chemical_list: D001500:BCG Vaccine; D014373:Tuberculin; D007371:Interferon-gamma