Interferon-gamma ELISPOT for the screening and diagnosis of latent tuberculosis infection in healthy population of China

The aim of this study was to analyze the combination of three kinds of in-house IFN-γ ELISPOT using peptide A53 and peptide mixtures (E6 + E7 and E6 + E7 + C14) with tuberculin skin test (TST) to detect latent TB infection (LTBI) in China. A total of 788 healthy people were recruited and analyzed by three kinds of IFN-g ELISPOT, 581 of them had TST results, of which 147 samples were also compared with the T- SPOT.TB test. The positive detection rates for T- SPOT.TB and three kinds of IFN-γ ELISPOT with A53, E6 + E7 and E6 + E7 + C14 were 14.28% (21/147), 29.43% (171/581), 23.24% (135/581) and 28.40% (165/581), respectively. These results were significantly lower than the positive TST results, which were positive in 82.99% (122/147) and 75.73% (440/ 581), respectively. The positive detection rates of three kinds of IFN-γ ELISPOT (31.60%, 26.65% and 32.11% in 788 cases, respectively) could better reflect over 40.00% of Mycobacterium tuberculosis (MTB) infection rate in China. Detection rates between contacts and non-contacts by three kinds of IFN-γ ELIS-POT were not significantly different (p > 0.05). It can be seen that the three kinds of in-house IFN-γ ELIS- POT might be used as a complementary tool of T- SPOT.TB for detecting LTBI in the healthy population of China.