- © 2006 Marshfield Clinic
Comparison of an In-house and a Commercial RD1-based ELISPOT-IFN-γ Assay for the Diagnosis of Mycobacterium tuberculosis Infection
- Paola Mantegani, MSc*,
- Federica Piana, MD*,
- Luigi Codecasa, MD,
- Laura Galli, MSc,
- Paolo Scarpellini, MD,
- Adriano Lazzarin, MD,
- Daniela Cirillo, MD and
- Claudio Fortis, MD
- Paola Mantegani, MSc, Clinic of Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
- Federica Piana, MD, Emerging Bacterial Pathogens Unit, San Raffaele Scientific Institute, Milan, Italy
- Luigi Codecasa, MD, Villa Marelli Institute, Lombardy Regional Reference Center for Tuberculosis Niguarda Hospital, Milan, Italy
- Laura Galli, MSc, Clinic of Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
- Paolo Scarpellini, MD, Clinic of Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
- Adriano Lazzarin, MD, Clinic of Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy and “Vita-Salute” San Raffaele University School of Medicine, Milan, Italy
- Daniela Cirillo, MD, Emerging Bacterial Pathogens Unit, San Raffaele Scientific Institute, Milan, Italy
- Claudio Fortis, MD, Clinic of Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
- Reprint Requests:
Claudio Fortis, MD, Clinic of Infectious Diseases, San Raffaele Scientific Institute, Via Stamira D’Ancona 20, 20127, Milano, Italy, Tel: +39-02-26437911, Fax: +39-02-26437989, E-mail: fortis.claudio{at}hsr.it
Abstract
Objective: To compare a RD1-based in-house ELISPOT-interferon-γ (IFN-γ) assay with a commercial (T-SPOT.TB™) assay for the diagnosis of Mycobacterium tuberculosis (TB) infection and the efficacy of the tuberculin skin test (TST) and ELISPOT assay in detecting latent TB infection (LTBI).
Design: Eighty-six subjects (65 household contacts of contagious TB-infected patients, 13 subjects with active or previous TB infection, and 8 with suspected TB infection) were consecutively recruited in the context of a surveillance program.
Methods: Enrolled subjects underwent the Mantoux TST and two different ELISPOT-IFN-γ assays: an in-house assay using a pool of selected M. tuberculosis peptides (MTP) and the commercial T-SPOT.TB assay.
Results: The in-house and commercial ELISPOT-IFN-γ assays showed almost complete concordance (99%) in diagnosing acute or LTBI.When comparing the efficacy of the TST with the in-house ELISPOT assay in detecting TB infection, a small agreement was observed (k=0.344, P<0.0001): 36% of the subjects with a positive TST were ELISPOT-MTP negative and 12% with a negative TST were ELISPOT-MTP positive. Furthermore, 78% of the ELISPOT-MTP negative individuals were ELISPOT- Bacillus Calmette-Guérin (BCG) positive, most of whom had received BCG vaccination.
Conclusion: Our in-house ELISPOT assay based on a restricted pool of highly selected peptides is equivalent to the commercial T-SPOT.TB assay, is cheaper and is probably not confounded, unlike the TST, by BCG vaccination in our setting
