Wang L, Ruan JX, Chen W, Wang XQ, Yu Y. Exploration and improvement of QuantiFERON-TB assay in patients with indeterminate results in clinical practice: A head-to-head study.
Clin Chim Acta 2023;
549:117559. [PMID:
37709113 DOI:
10.1016/j.cca.2023.117559]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/13/2023] [Accepted: 09/11/2023] [Indexed: 09/16/2023]
Abstract
BACKGROUND
We implemented the QuantiFERON-TB Gold In-Tube (QFT-GIT) based on peripheral blood mononuclear cells (QFT-PBMCs) and QFT Gold Plus (QFT-Plus) in patients with indeterminate results, and use Mit-Nil value to identify false negatives and impaired cellular immunity.
METHODS
One hundred seventy-one out of 2480 patients who had a QFT-GIT test were prospectively recruited and classified as high Nil (n = 35), low Mit (n = 75) and control (n = 61) cohorts. Head-to-head comparisons, i.e., QFT-PBMCs vs. QFT-GIT in high Nil cohort, QFT-Plus vs. QFT-GIT in low Mit cohort, and QFT-PBMCs vs. QFT-GIT in controls, were performed. Lymphocyte subsets counts were conducted in low Mit and control cohorts.
RESULTS
A significant reduction of positive rate only occurred in Mit-Nil < 6 IU/ml (p < 0.001). QFT-PBMCs yielded 100 % valid results and had a significant Nil decline in high Nil cohort (0.98 ± 1.06 vs. 9.55 ± 0.64 IU/ml, p < 0.0001), while correlated well with QFT-GIT for qualitative (Cohen's k = 0.93) and quantitative (TB-Ag [R2 = 0.91] and Mit [R2 = 0.94]) analyses. QFT-Plus produced 61.3 % valid results and had a significant Mit increase in low Mit cohort (0.82 ± 0.95 vs. 0.17 ± 0.11 IU/ml, p < 0.0001). Mit-Nil value significantly correlated with lymphocyte subsets counts (R:0.49-0.56, p < 0.0001), separately corresponding to thresholds of 4.26, 5.33, 5.55 and 5.81 IU/ml for predicting decreased total lymphocyte, T lymphocyte, CD4+ and CD8+ cells.
CONCLUSIONS
QFT that replacing whole blood with PBMCs should be recommended to handle high Nil samples, and QFT-Plus can declined the frequency of low Mit results. In addition, Mit-Nil < 6 and 5.81 IU/ml are potential thresholds to identify the risk of false negatives and impaired cellular immunity, respectively.
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