CD4 response of QuantiFERON-TB Gold Plus for positive consistency of latent tuberculosis infection in patients on dialysis.

ABSTRACT

A significantly negative reversion in the QuantiFERON-TB Gold In-tube (QFT-GIT) test is reported in patients on dialysis, which makes the results unreliable. The CD4 and CD8 responses of the QFT-Gold plus (QFT-Plus) may have better positive consistency, but this needs to be investigated. We enrolled dialysis patients with baseline positive QFT-GIT0 results and conducted two rounds of follow-up paired QFT-GIT1&2 and QFT-Plus1&2 tests at an interval of 6 months. The positive consistency, concordance, and discordance of the QFT results were analyzed. A total of 236 patients on dialysis were screened, and 73 participants with positive QFT-GIT0 results were enrolled. The baseline QFT-GIT0 response was higher in the 1st QFT-Plus1(+) group than in the QFT-Plus1(-) group, but insignificantly different between the 1st QFT-GIT1(+) and QFT-GIT1(-) groups. The two assays had good correlation when concurrently tested. Fifty-three subjects completed a second round of the QFT-GIT2 and QFT-Plus2. Persistent positivity was higher with the QFT-Plus2 (81.8%) than with the QFT-GIT2 (58.8%, p = 0.040). The QFT-GIT1 and QFT-Plus1 CD4 responses were higher in patients with persistent positivity than in those with negative reversion, whereas the difference of the QFT-Plus TB1 and TB2 data, representative of the CD8 response, were similar between positive persistence and negative reversion. In conclusion, the QFT-Plus provides more reliable positive consistency than does the QFT-GIT. The CD4 interferon-γ response might play a role in maintaining positivity of LTBI.