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Published on: February 5, 2020
Tracking immunodynamics by identification of S-G2/M-phase T cells in human peripheral blood
Miguel Muñoz-Ruiz1, Irma Pujol-Autonell2, Hefin Rhys3
1Immunosurveillance Laboratory, The Francis Crick Institute, London, UK.
Insights
Tracking T cells in the S-G2/M phases of the cell-cycle (TDS cells) using refined flow cytometry offers new immunodynamic insights from peripheral blood. This method reveals immune responses in various conditions, including autoimmune diseases.
Area of Science:
- Immunology
- Cell Biology
- Flow Cytometry
Background:
- Immuno-monitoring traditionally relies on static T cell metrics from blood.
- Dynamic immune assessments often use in vitro stimulation, introducing variability.
- Peripheral blood is underutilized for insights into dynamic immune responses and tissue immunopathology.
Purpose of the Study:
- To develop and validate a refined flow cytometry approach for quantifying T cells in cell-cycle phases (TDS cells).
- To investigate the utility of TDS cells for assessing immunodynamic scenarios in healthy donors, infectious mononucleosis patients, and type 1 diabetes (T1D) patients.
- To explore the potential of TDS cells as biomarkers for immune response dynamics and tissue immunopathology.
Main Methods:
- Development of refined flow cytometric protocols for reliable quantification of T cells in S-G2/M phases (TDS cells).
- Analysis of TDS cell frequencies in CD8+ T cells and a subset of CD4+ T regulatory cells.
- Comparison of TDS cell levels in healthy donors, infectious mononucleosis patients, and recently-diagnosed T1D patients.
Main Results:
- Refined protocols enabled accurate quantification of TDS cells, which are often missed or misidentified with standard methods.
- TDS cells were reproducibly more abundant in CD8+ T cells and a specific T-regulatory CD4+ T cell subset.
- Substantial increases in TDS cells were observed in infectious mononucleosis patients and a subset of T1D patients.
- Islet antigen-reactive TDS cells correlated with aggressive T cell effector phenotypes in T1D patients.
Conclusions:
- Tracking TDS cells offers a novel and widely applicable method for assessing immune response dynamics in peripheral blood.
- TDS cell analysis can provide insights into immune events occurring within tissues, even in organ-specific autoimmune diseases.
- This approach holds promise for understanding and monitoring various immune conditions, including those with underlying tissue immunopathology.
Abstract:
The ready availability of human blood makes it the first choice for immuno-monitoring. However, this has been largely confined to static metrics, particularly resting T cell phenotypes. Conversely, dynamic assessments have mostly relied on cell stimulation in vitro which is subject to multiple variables. Here, immunodynamic insights from the peripheral blood are shown to be obtainable by applying a revised approach to cell-cycle analysis. Specifically, refined flow cytometric protocols were employed, assuring the reliable quantification of T cells in the S-G2/M phases of the cell-cycle (collectively termed "T Double S" for T cells in S-phase in Sanguine: in short "TDS" cells). Without protocol refinement, TDS could be either missed, as most of them layed out of the conventional lymphocyte gates, or confused with cell doublets artefactually displaying high DNA-content. To illustrate the nature of TDS cells, and their relationship to different immunodynamic scenarios, we examined them in healthy donors (HD); infectious mononucleosis (IM) patients versus asymptomatic EBV+ carriers; and recently-diagnosed T1D patients. TDS were reproducibly more abundant among CD8+ T cells and a defined subset of T-regulatory CD4+ T cells, and were substantially increased in IM and a subset of T1D patients. Of note, islet antigen-reactive TDS cell frequencies were associated with an aggressive T cell effector phenotype, suggesting that peripheral blood can reflect immune events within tissues in T1D, and possibly in other organ-specific autoimmune diseases. Our results suggest that tracking TDS cells may provide a widely applicable means of gaining insight into ongoing immune response dynamics in a variety of settings, including tissue immunopathologies where the peripheral blood has often not been considered insightful.
