Lougaris, V. | Search bioRxiv

bioRxiv2025

A high-resolution, unbiased analysis of the cellular immune response to Epstein-Barr virus

More than 95% of humans are infected with Epstein-Barr virus (EBV), yet although EBV infection has been associated with inflammatory and autoimmune diseases, lymphoproliferative disorders, and several types of cancer, for the vast majority of infected people the infection is asymptomatic as EBV replication is controlled by the immune system. Immunity against this virus has been studied since the discovery of EBV in the 1960s, and although important insights have been made, no unbiased, global studies of immune responses to EBV in healthy seropositive subjects have been reported. Here we describe a novel protocol to study the cellular immune response to EBV, detecting lymphocytes that respond to EBV via analyses of proliferation or induced expression of activation markers and cytokines. Using this system we sequenced, for the first time at a single-cell level, the transcriptome of all cells capable of responding to EBV in healthy individuals and in patients with inborn errors of immunity (IEI) associated with susceptibility to EBV infection. Lymphocyte cytotoxicity appears to be crucial for the proper control of EBV-infection, while a proportionate T-regulatory cell response likely helps to avoid excessive immunity and immune pathology. We also show that {gamma}{delta} T cells expressing the TCR V{delta}1 chain use various activating natural killer (NK) cell receptors to recognise and kill EBV-infected lymphoblastoid cell lines (LCLs) and thus could be a promising candidate for allogeneic cell therapy for EBV-associated lymphoproliferative disorders in patients with either primary or secondary immunodeficiencies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=186 HEIGHT=200 SRC="FIGDIR/small/681317v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@116ad85org.highwire.dtl.DTLVardef@1da33d7org.highwire.dtl.DTLVardef@81a2a6org.highwire.dtl.DTLVardef@dd571d_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2021

Follicular helper T cell signature of replicative exhaustion, apoptosis and senescence in common variable immunodeficiency

BackgroundCommon variable immunodeficiency (CVID) is the most frequent primary antibody deficiency. A significant number of CVID patients are affected by various manifestations of immune dysregulation such as autoimmunity. Follicular T cells cells are thought to support the development of CVID by providing inappropriate signals to B cells during the germinal center (GC) response. ObjectivesWe determined the possible role of follicular helper (Tfh) and follicular regulatory T (Tfr) cells in patients with CVID by phenotypic, molecular, and functional studies. MethodsWe analyzed the frequency, phenotype, transcriptome, and function of circulating Tfh cells in the peripheral blood of 27 CVID patients (11 pediatric and 16 adult) displaying autoimmunity as additional phenotype and compared them to 106 (39 pediatric and 67 adult) age-matched healthy controls. We applied Whole Exome Sequencing (WES) and Sanger sequencing to identify mutations that could account for the development of CVID and associate with Tfh alterations. ResultsA group of CVID patients (n=9) showed super-physiological frequency of Tfh1 cells and a prominent expression of PD-1 and ICOS, as well as a Tfh RNA signature consistent with highly active, but exhausted and apoptotic cells. Plasmatic CXCL13 levels were elevated in these patients and positively correlated with Tfh1 cell frequency, PD-1 levels, and an elevated frequency of CD21loCD38lo autoreactive B cells. Monoallelic variants in RTEL1, a telomere length- and DNA repair-related gene, were ideintified in four patients belonging to this group. Lymphocytes with highly shortened telomeres, and a Tfh signature enriched in genes involved in telomere elongation and response to DNA damage were seen. Histopathological analysis of the spleen in one patient showed reduced amount and size of the GC that, unexpectedly, contained an increased number of Tfh cells. ConclusionThese data point toward a novel pathogenetic mechanism in a group of patients with CVID, whereby alterations in DNA repair and telomere elongation might be involved in GC B cells, and acquisition of a Th1, highly activated but exhausted and apoptotic phenotype by Tfh cells.

immunology↗