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Updated: Nov 21, 2025
Separation of Immune Cell Subpopulations in Peripheral Blood Samples from Children with Infectious Mononucleosis
Published on: September 7, 2022
Characterizing EBV-associated lymphoproliferative diseases and the role of myeloid-derived suppressor cells
Paul J Collins1,2, Christopher P Fox3,4, Lindsay George5
1Institute for Immunology and Immunotherapy.
Insights
Chronic active Epstein-Barr virus (CAEBV) involves EBV infection and T/NK cell proliferation. Myeloid-derived suppressor cells inhibit T-cell growth, likely hindering immune control in CAEBV and hemophagocytic lymphohistocytosis (HLH).
Area of Science:
- Immunology
- Virology
- Oncology
Background:
- Chronic active Epstein-Barr virus (CAEBV) and hemophagocytic lymphohistocytosis (HLH) involve Epstein-Barr virus (EBV) infection and T/NK cell proliferation.
- The mechanisms of immune evasion and disease progression in CAEBV remain poorly understood.
Purpose of the Study:
- To investigate the phenotype and function of EBV-infected cells and identify immune evasion mechanisms in CAEBV.
- To compare infected and non-infected lymphocyte subsets in patients with CAEBV and HLH.
Main Methods:
- Developed a multicolor flow cytometry technique with in situ hybridization for EBV-encoded RNAs (EBERs).
- Analyzed blood samples ex vivo to identify, phenotype, and functionally compare EBER-positive (infected) and EBER-negative (non-infected) lymphocyte subsets.
Main Results:
- Characterized CAEBV/HLH cases with monoclonal EBV-activated T-cell and sometimes NK-cell populations.
- Observed progression of infected cells despite standard therapy, with detectable cytotoxic CD8+ T cells.
- Identified a high prevalence of myeloid-derived suppressor cells (MDSCs) exhibiting potent T-cell inhibition in CAEBV patients.
Conclusions:
- MDSCs significantly inhibit T-cell proliferation in CAEBV patients.
- The presence of MDSCs likely explains the host's failure to control EBV-positive T/NK-cell proliferation, contributing to disease progression.
Abstract:
Chronic active Epstein-Barr virus (CAEBV) typically presents as persistent infectious mononucleosis-like disease and/or hemophagocytic lymphohistocytosis (HLH), reflecting ectopic Epstein-Barr virus (EBV) infection and lymphoproliferation of T and/or NK cells. Clinical behavior ranges from indolent, stable disease through to rapidly progressive, life-threatening disease. Although it is thought the chronicity and/or progression reflect an escape from immune control, very little is known about the phenotype and function of the infected cells vs coresident noninfected population, nor about the mechanisms that could underpin their evasion of host immune surveillance. To investigate these questions, we developed a multicolor flow cytometry technique combining phenotypic and functional marker staining with in situ hybridization for the EBV-encoded RNAs (EBERs) expressed in every infected cell. This allows the identification, phenotyping, and functional comparison of infected (EBERPOS) and noninfected (EBERNEG) lymphocyte subset(s) in patients' blood samples ex vivo. We have characterized CAEBV and HLH cases with monoclonal populations of discrete EBV-activated T-cell subsets, in some cases accompanied by EBV-activated NK-cell subsets, with longitudinal data on the infected cells' progression despite standard steroid-based therapy. Given that cytotoxic CD8+ T cells with relevant EBV antigen specificity were detectable in the blood of the best studied patient, we searched for means whereby host surveillance might be impaired. This revealed a unique feature in almost every patient with CAEBV studied: the presence of large numbers of myeloid-derived suppressor cells that exhibited robust inhibition of T-cell growth. We suggest that their influence is likely to explain the host's failure to contain EBV-positive T/NK-cell proliferation.
