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- Title
Platelets correlate with false negative T-SPOT.TB results by inhibiting interferon-γ production in T cells via degranulation.
- Authors
Jiayue Rao; Yuting Rao; Yang Guo; Mei Jiang; Dan Long; Qing Luo; Zikun Huang; Junming Li
- Abstract
Background: T-SPOT.TB (T-SPOT) is widely used for the detection of Mycobacterium tuberculosis infection by detecting interferon-gamma (IFN-&#947) release in T lymphocytes. This assay is performed on peripheral blood mononuclear cells (PBMCs) separated by Ficoll density gradient centrifugation, which often contain some residual platelets. Here, we investigated the impact of platelets on T-SPOT assay and related mechanisms. Methods: The correlation between platelet count, platelet-to-lymphocyte ratio (PLR), and the IFN-g secreting T cells (ISCs) in positive control wells of T-SPOT assay were retrospectively analyzed. T-SPOT assay was performed with un-treated PBMCs, platelets-removed PBMCs, and platelets-enriched PBMCs to confirm the impact of platelets on T-SPOT assay. The activation of platelets and their impact on IFN-g production in T cells were detected by flow cytometry (FCM). Platelets and T cells were cultured in a mixed culture system and co-culture system respectively, followed by detection of the frequencies of IFN-g-producing T cells and the levels of intracellular IFN-γ in T cells by FCM. Moreover, the effect of platelet releasate on the T-SPOT assay was evaluated. Results: The ISCs in positive control wells of the T-SPOT assay showed a significant decrease with the increase in platelet count. The PLR of the peripheral blood were negatively correlated with the ISCs in positive control wells of the T-SPOT assay. Removal or enrichment of platelets significantly increased or decreased the ISCs and the positive rate of T-SPOT. Inhibition of platelet activation significantly increased the ISCs of T-SPOT. The frequencies of IFN-&#94-producing T cells in PBMCs and the levels of intracellular IFN-g were significantly reduced by the addition of platelets, both in the mixed culture system and the co-culture system. Platelet releasate upon thrombin activation significantly decreased the ISCs of T-SPOT. Conclusions: Platelets correlate with negative T-SPOT results by inhibiting IFN-γ production in T cells via degranulation.
- Subjects
BLOOD platelet aggregation; MONONUCLEAR leukocytes; BLOOD platelets; PLATELET count; T cells; DENSITY gradient centrifugation; PLATELET lymphocyte ratio
- Publication
Frontiers in Cellular & Infection Microbiology, 2022, Vol 12, p1
- ISSN
2235-2988
- Publication type
Article
- DOI
10.3389/fcimb.2022.937416