Table 1.
Comparison of immunodiagnostic test characteristics
| Method | Antigen | Time to result | Advantage | Disadvantage | ||
|---|---|---|---|---|---|---|
| Skin tests | Mantoux TST Readout: Skin induration after tuberculin injection (mm) |
PPD | 48-72h | - inexpensive - recommended for children - largest body of clinical experience |
- affected by BCG-vaccination - 2 visits - low sensitivity in immunocompromised - subject to human variability in placement and reading |
|
| Diaskintest©: Readout: Skin induration after antigen injection (mm) |
ESAT-6 CFP-10 |
48-72h | - not affected by BCG-vaccination | - 2 visits - sensitivity in immunocompromised not known - available only in Russia and Eastern Europe |
||
| C-Tb skintest©: Readout: Skin induration after antigen injection (mm) |
C-Tb (rESAT-6 and rCFP-10) | 48-72h | -not affected by BCG-vaccination | - 2 visits - sensitivity in immunocompromised not known - not yet commercially available |
||
| IGRAs | ELISPOT | T-Spot.TB©: (IFN-γ producing cells/250.000 PBMC) Readout: SFC |
ESAT-6 CFP-10 (peptides) |
< 24h | - not affected by BCG-vaccination - optimized differentiation between LTBI and TB by comparison of peripheral and local immune response |
- no differentiation between LTBI and TB in blood - more elaborate technique compared to QFT-G-IT |
| ELISAs | QFT-G-IT©: (antigen-specific IFN-γ release in whole blood) Readout: IU/ml |
ESAT-6 CFP-10 Tb 7.7 (peptides) |
< 24h | - not affected by BCG-vaccination - operational test advantages compared to ELISPOT |
- no differentiation between LTBI and TB in blood | |
| QFT-plus©: (antigen-specific IFN-γ release in whole blood) Readout: IU/ml |
TB1 (ESAT-6, CFP-10) TB2 (TB1 peptides plus short CFP-10 peptides) |
< 24h | - not affected by BCG-vaccination - operational test advantages compared to ELISPOT - manufacturer suggests higher sensitivity compared to QFT-G-IT |
- no differentiation between LTBI and TB in blood | ||
BCG, Bacille Calmette-Guérin; CFP-10, culture filtrate protein; ESAT-6, early secreted antigenic target; IFN-γ, interferon-γ; PPD, purified protein derivative; PBMC, peripheral blood mononuclear cells; TST, tuberculin skin test.