Abstract
Objectives:
Diffuse large B-cell lymphoma (DLBCL) constitutes 30-40% of non-Hodgkin lymphoma cases. Despite therapeutic advances, persistence of relapsed cases has been linked to the complex tumor microenvironment (TME) and its interactions with lymphoma cells. In particular, characterising T-cell subsets, including rare cell types, and their interplay with the remaining TME is crucial for unravelling DLBCL pathogenesis and refining therapeutic strategies.
Methods:
Using flow and spectral cytometry with unsupervised analysis, we investigated T-cell subpopulations across DLBCL biopsies and control lymph nodes (LN). We also inferred communication pathways between T cells and other immune cells in the TME based on the correlation of ligand-receptor expression.
Results:
Our analysis revealed a higher frequency of CD8+ follicular regulatory T (Tfr) cells in DLBCL biopsies compared to control LN. These cells exhibited an effector-memory phenotype (CD45RA- CCR7-), expressed follicular markers (PD-1+ CXCR5+) and had a regulatory profile (CD127- CD25+) along with an activation/co-stimulatory signature (HLA-DR+, ICOS+, CD95+). Correlation analysis highlighted a co-stimulatory interaction between lymphoma B cells and CD8+ Tfr cells through the ICOS/ICOSL pathway, which may contribute to a protumor effect. Validation in independent scRNAseq and flow cytometry datasets confirmed the notable prevalence of CD8+ Tfr cells in DLBCL biopsies.
Conclusions:
Our study highlights the utility of high-dimensional computational cytometry in elucidating T-cell subpopulations, including an increased frequency of CD8+ follicular regulatory T cells and their communication patterns within the DLBCL TME. This unbiased approach sheds light on novel cellular mechanisms in DLBCL, uncovering potential targets and biomarkers for immunotherapy.