To the Editors:
We read with interest the paper by Leyten et al. 1, which appeared in the June 2007 issue of the European Respiratory Journal (ERJ). Leyten et al. 1 showed that prior tuberculin skin tests (TST) do not induce false-positive QuantiFERON®-TB Gold in-tube (QFT-GIT) assay results when evaluated in the days immediately following TST administration. In the same issue of the ERJ, Naseer et al. 2 reported the results of a study of 10 subjects without risk for tuberculosis infection, who were tested with QFT-GIT and the T-SPOT.TB assay (Oxford Immunotec, Abingdon, UK) before, 48 h and 6 weeks after TST administration. Naseer et al. 2 confirmed the results of Leyten et al. 1 in the first days following skin testing; however, after 6 weeks, three out of nine individuals turned from negative to positive with QFT-GIT, and none of the subjects turned from negative to positive with T-SPOT.TB. On this basis, Naseer …
