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Updated: Aug 6, 2026

Enzyme-linked Immunospot Assay (ELISPOT): Quantification of Th-1 Cellular Immune Responses Against Microbial Antigens
Published on: November 23, 2010
Interferon-gamma responses to ESAT-6 in tuberculosis patients early into and after anti-tuberculosis treatment
R A Ferrand1, G H Bothamley, A Whelan
1Immunology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom. rabferr@fastmail.fm
Objective:
To investigate T-cell responses to ESAT-6 by an interferon-gamma (IFN-gamma) ex vivo enzyme-linked immunospot (ELISpot) assay in tuberculosis (TB) patients early during treatment and in patients who have completed a course of anti-tuberculosis chemotherapy.
Design:
T-cell responses following overnight stimulation with 6-kD early secretory antigenic target (ESAT-6) antigen were compared to responses obtained using cells cultured with ESAT-6 for 6 days, using an ELISpot assay.
Results:
In the ex vivo ELISpot assay, the median IFN-gamma responses in TB patients, irrespective of treatment status, were significantly higher than in healthy BCG-vaccinated controls. In the 6-day ELISpot assay, median IFN-gamma responses were significantly higher in TB patients who had completed treatment than in patients early during therapy. There was considerable individual variability in the degree of expansion of ESAT-6 specific T-cells from day 1 to day 6 in both treatment groups.
Conclusion:
Further studies are required to assess which type of assay provides the best indicator of a memory T-cell response and how ESAT-6 specific T-cells relate to protective immunity in TB infection.
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08:13Optimized Interferon-gamma ELISpot Assay to Measure T Cell Responses in the Guinea Pig Model after Vaccination
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