{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T08:41:02Z","timestamp":1791189662043,"version":"4.1.0"},"reference-count":39,"publisher":"Oxford University Press (OUP)","issue":"1","license":[{"start":{"date-parts":[[2009,7,1]],"date-time":"2009-07-01T00:00:00Z","timestamp":1246406400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2009,7,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>When using a two-step screening strategy it appears safe to perform a QuantiFERON-TB-GIT or T-SPOT.TB IGRA within 3 days of performing the TST. A 3-spot or 80% IFN-\u03b3 response variation, on either side of baseline values, explains 95% of the short-term variability and may be useful for interpreting conversions and reversions, and values close to the cut-point.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Rationale<\/jats:title>\n                    <jats:p>The optimal strategy for the diagnosis of latent tuberculosis infection is controversial. Adoption of a two-step strategy (tuberculin skin test [TST] followed by an IFN-\u03b3 release assay [IGRA], compared with an IGRA alone), may be limited by TST-mediated boosting of subsequent IGRA responses. Assessment of within-subject IGRA variability will aid in establishing thresholds for conversions and reversions, and interpretation of serial testing results.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To determine short-term IGRA variability and the impact of TST on subsequent IGRA results.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Within-subject variability and TST-mediated boosting of IGRA responses were evaluated in 26 South African participants with varying exposure risk. IGRAs (T-SPOT.TB, QuantiFERON-TB Gold In-Tube [QuantiFERON-TB-GIT], PPD, and heparin-binding hemagglutinin) were repeated four times over 21 days pre-TST, and on Days 3, 7, 28, and 84 post-TST administration.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Measurements and Main Results<\/jats:title>\n                    <jats:p>All participants showed within-subject IGRA variability. Changes of \u00b13 spots (T-SPOT.TB) or \u00b180% from the mean IFN-\u03b3 response (QuantiFERON-TB-GIT) over 3 weeks explained 95% of the variability. Spontaneous conversions\/reversions occurred in 7 of 26 subjects (27%) (6 for T-SPOT.TB and 1 for QuantiFERON-TB-GIT [P = 0.049]) during the within-patient variability studies (pre-TST). After the TST eight subjects (33%) boosted above the defined baseline variability. By Day 7 post-TST, but not Day 3, 2 (12.5%) initially IGRA-negative test subjects converted. By contrast, boosting of PPD and heparin-binding hemagglutinin occurred by Day 3 post-TST.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1164\/rccm.200811-1704oc","type":"journal-article","created":{"date-parts":[[2009,4,2]],"date-time":"2009-04-02T22:03:41Z","timestamp":1238709821000},"page":"49-58","source":"Crossref","is-referenced-by-count":160,"title":["Within-Subject Variability and Boosting of T-Cell Interferon-\u03b3 Responses after Tuberculin Skin Testing"],"prefix":"10.1093","volume":"180","author":[{"given":"Richard N.","family":"van Zyl-Smit","sequence":"first","affiliation":[{"name":"Lung Infection and Immunity Unit, Division of Pulmonology and UCT Lung Institute Department of Medicine, University of Cape Town, Cape Town, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Madhukar","family":"Pai","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kwaku","family":"Peprah","sequence":"additional","affiliation":[{"name":"Lung Infection and Immunity Unit, Division of Pulmonology and UCT Lung Institute Department of Medicine, University of Cape Town, Cape Town, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard","family":"Meldau","sequence":"additional","affiliation":[{"name":"Lung Infection and Immunity Unit, Division of Pulmonology and UCT Lung Institute Department of Medicine, University of Cape Town, Cape Town, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jackie","family":"Kieck","sequence":"additional","affiliation":[{"name":"Department of Radiology, University of Cape Town and Groote Schuur Hospital"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"June","family":"Juritz","sequence":"additional","affiliation":[{"name":"Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Motasim","family":"Badri","sequence":"additional","affiliation":[{"name":"Lung Infection and Immunity Unit, Division of Pulmonology and UCT Lung Institute Department of Medicine, University of Cape Town, Cape Town, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alimuddin","family":"Zumla","sequence":"additional","affiliation":[{"name":"Centre for Infectious Diseases and International Health, Royal Free and University College Medical School, London, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leonardo A.","family":"Sechi","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Biomediche, University of Sardinia, Sassari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric D.","family":"Bateman","sequence":"additional","affiliation":[{"name":"1Lung Infection and Immunity Unit, Division of 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