RT Journal Article SR Electronic T1 The tuberculin skin test in relation to immunological in vitro reactions in BCG-vaccinated healthcare workers JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 376 OP 380 DO 10.1183/09031936.01.00086901 VO 18 IS 2 A1 H. Fjällbrant A1 M. Ridell A1 L.O. Larsson YR 2001 UL http://erj.ersjournals.com/content/18/2/376.abstract AB The aim was to study the tuberculin skin test in relation to immunological in vitro reactions in bacille Calmette-Guérin (BCG)-vaccinated healthcare workers.The present study was performed in Sweden, a country with a low incidence of tuberculosis, a high BCG vaccination efficacy and high tuberculin conversion rates. BCG-vaccinated healthcare workers (n=381) were tuberculin skin tested. From these, 11 subjects with negative tuberculin reactions (<6 mm) were matched for age and sex with 11 subjects with large positive reactions (≥15 mm). Lymphocyte transformation and the production of interferon-gamma (IFN-γ) were analysed after stimulation in vitro of peripheral blood mononuclear cells with tuberculin purified protein derivative, heat-killed tubercle bacilli and a culture filtrate from tubercle bacilli.In the tuberculin-positive group the lymphocyte transformation response was 2–3 times larger, and IFN-γ production was 7–10 times larger, than in the tuberculin-negative group (p<0.001).The present results suggest that a positive tuberculin skin test in bacille Calmette-Guérin-vaccinated subjects indicates a stronger immune response of the protective T-helper 1-type than does a negative test. In similar settings, the study supports the traditional practice of regarding the tuberculin skin test in bacille Calmette-Guérin-vaccinated subjects as an indicator of a protective immune response against tuberculosis.This study received generous financial support from the Oscar and Hanna Björkbom Fund and the Swedish Heart and Lung Foundation.