Evolution of Blood Innate Immune Cell Phenotypes Following SARS-CoV-2 Infection in Hospitalized Patients with COVID-19.

Innate immune cells appear to have an important implication in the resolution and/or the aggravation of the COVID-19 pathogenesis after infection with SARS-CoV-2. To better appreciate the role of these cells during COVID-19, changes in blood eosinophil, the neutrophil and monocyte count, and levels of surface protein markers have been reported. However, analyses at several timepoints of multiple surface markers on granulocytes and monocytes over a period of one month after a SARS-CoV-2 infection are missing.

Enhanced Siglec-8 and HLA-DR and reduced CRTH2 surface expression highlight a distinct phenotypic signature of circulating eosinophils in atopic dermatitis.

Atopic dermatitis and other type 2 immune response diseases are often linked to elevated eosinophil levels in the blood. Although the role of eosinophils in atopic dermatitis pathophysiology is suspected, it remains unclear. The development of new treatments targeting the type 2 response, particularly cytokines involved in eosinophil activation and chemotaxis, makes it necessary to identify potential eosinophil profiles in atopic dermatitis that may respond to these treatments.

Studying antigen-specific T cells through a streamlined, whole blood-based extracellular approach.

Techniques currently used for the study of antigen-specific T-cell responses are either poorly informative or require a heavy workload. Consequently, many perspectives associated with the broader study of such approaches remain mostly unexplored in translational research. However, these could benefit many fields including but not limited to infectious diseases, oncology, and vaccination.

Immunogenicity of BNT162b2 vaccine booster against SARS-CoV-2 Delta and Omicron variants in nursing home residents: A prospective observational study in older adults aged from 68 to 98 years.

Background: The present study aimed to evaluate the persistent immunogenicity offered by a third dose of BNT162b2 against Delta and Omicron variants, in nursing home (NH) residents.

Methods: In this monocenter prospective observational study, anti-spike IgG levels, S1 domain reactive T cell counts, serum neutralizing antibody titers against Delta and Omicron variants were compared before and up to three months after the BNT162b2 booster dose, in NH residents without COVID-19 (COVID-19 naive) or with COVID-19 prior to initial vaccination (COVID-19 recovered).

Findings: 106 NH residents (median [interquartile range] age: 86·5 [81;91] years) were included.

Impaired Functional T-Cell Response to SARS-CoV-2 After Two Doses of BNT162b2 mRNA Vaccine in Older People.

Long-term care facility (LTCF) older residents display physiological alterations of cellular and humoral immunity that affect vaccine responses. Preliminary reports suggested a low early postvaccination antibody response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The aim of this study was to focus on the specific T-cell response.

Severe SARS-CoV-2 patients develop a higher specific T-cell response.

Objectives: Assessment of the adaptive immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is crucial for studying long-term immunity and vaccine strategies. We quantified IFNγ-secreting T cells reactive against the main viral SARS-CoV-2 antigens using a standardised enzyme-linked immunospot assay (ELISpot).

Methods: Overlapping peptide pools built from the sequences of M, N and S viral proteins and a mix (MNS) were used as antigens.

Monitoring CAR T-cells using flow cytometry.

Background: Chimeric antigen receptor (CAR) T-cell therapy is considered as a major scientific breakthrough in cancer immunotherapy. The success of adoptive CAR T-cell therapy for cancer has inspired researchers to expand indications into the area of solid tumors, autoimmune and infectious diseases. The most important factors influencing outcome and durability of the response after infusion of CAR T-cell are proliferation and persistence of this cell subset.

Pancreatic beta cells persistently infected with coxsackievirus B4 are targets of NK cell-mediated cytolytic activity.

It has been suggested that the persistence of coxsackieviruses-B (CV-B) in pancreatic beta cells plays a role in the pathogenesis of type 1 diabetes (T1D). Yet, immunological effectors, especially natural killer (NK) cells, are supposed to clear virus-infected cells. Therefore, an evaluation of the response of NK cells to pancreatic beta cells persistently infected with CV-B4 was conducted.

Donor-derived CD4/CCR7 T-cell impact on acute GVHD incidence following haplo-HCT after reduced intensity conditioning and posttransplant cyclophosphamide.

In previous studies, we and others observed in patients undergoing HLA-matched hematopoietic cell transplantation that high proportion of donor-derived CD4/CCR7 T cells were associated with an increased risk of acute GVHD without any interference in relapse incidence. We investigated the impact of donor-derived CD4/CCR7 T cells on patient outcome in haploidentical settings where posttransplant cyclophosphamide is used. We analyzed T-cell subsets in grafts of 29 adult patients who underwent first haploidentical transplant following reduced intensity conditioning.

A standardized flow cytometry procedure for the monitoring of regulatory T cells in clinical trials.

Background: Quantification of regulatory T cells (Tregs) is crucial in immunomonitoring in clinical trials as this cell population has been shown to be involved in a wide range of diseases, including cancers, autoimmune diseases, infections, and allergies. Human Tregs are defined as CD4 CD25 CD127 FoxP3 cells, and the standardization of their staining by flow cytometry is a challenge, especially in multicenter clinical trials, notably because of the intracellular location of FoxP3.

Method: A flow cytometry staining procedure was settled and standardized to measure human Tregs in peripheral whole blood using precoated dried antibodies in ready-to-use tubes.

Coxsackievirus B4 Can Infect Human Peripheral Blood-Derived Macrophages.

Beyond acute infections, group B coxsackieviruses (CVB) are also reported to play a role in the development of chronic diseases, like type 1 diabetes. The viral pathogenesis mainly relies on the interplay between the viruses and innate immune response in genetically-susceptible individuals. We investigated the interaction between CVB4 and macrophages considered as major players in immune response.

CD3-CD4+ lymphoid variant of hypereosinophilic syndrome: nodal and extranodal histopathological and immunophenotypic features of a peripheral indolent clonal T-cell lymphoproliferative disorder.

The CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome is characterized by hypereosinophilia and clonal circulating CD3(-)CD4(+) T cells. Peripheral T-cell lymphoma has been described during this disease course, and we observed in our cohort of 23 patients 2 cases of angio-immunoblastic T-cell lymphoma. We focus here on histopathological (n=12 patients) and immunophenotypic (n=15) characteristics of CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome.

A low effective dose of interleukin-7 is sufficient to maintain cord blood T cells alive without potentiating allo-immune responses.

Slow reconstitution of T cell immunity remains a critical issue after umbilical cord blood (CB) transplantation. Although this may be a consequence of the low cell dose, it may also reflect the propensity of naïve T cells, which predominate in CB, to undergo apoptotic cell death. Exogenous interleukin 7 (IL-7) can prevent apoptosis of naïve T cells, but at high concentrations, IL-7 may also expand alloreactive T cells, thereby aggravating the risk of graft-versus-host disease.

The lymphoid variant of hypereosinophilic syndrome: study of 21 patients with CD3-CD4+ aberrant T-cell phenotype.

The CD3-CD4+ aberrant T-cell phenotype is the most described in the lymphoid variant of hypereosinophilic syndrome (L-HES), a rare form of HES. Only a few cases have been reported, and data for these patients are scarce. To describe characteristics and outcome of CD3-CD4+ L-HES patients, we conducted a national multicentric retrospective study in the French Eosinophil Network.

Naïve subset develops the most important alloreactive response among human CD4+ T lymphocytes in human leukocyte antigen-identical related setting.

In longitudinal clinical studies, receiving a high percentage of allogeneic donor-derived CD4(+) CCR7(+) T cells, which include naïve and central memory subsets have been correlated with increased incidence and severity of acute GVHD. Whether naïve and central memory CD4(+) T-cell subsets contribute more or equally to alloimmune responses are still unclear in human. The aim of this study was to investigate in vitro the alloreactive response of purified naïve, central memory, and effector memory CD4(+) T-cell subsets in HLA identical setting.

Defect in recruiting effector memory CD8+ T-cells in malignant pleural effusions compared to normal pleural fluid.

Background: Malignant pleural effusions (MPE) are a common and fatal complication in cancers including lung or breast cancers, or malignant pleural mesothelioma (MPM). MPE animal models and immunotherapy trials in MPM patients previously suggested defects of the cellular immunity in MPE. However only few observational studies of the immune response were done in MPM patients, using questionable control groups (transudate…).

Primed status of transitional B cells associated with their presence in the cerebrospinal fluid in early phases of multiple sclerosis.

In the present study we showed that transitional B cells of patients with clinically isolated syndrome (CIS) and relapsing-remitting multiple sclerosis (RR-MS) are reduced in the peripheral blood (PB) (5.5- and 3.7-fold, respectively).

B-cell subsets up-regulate α4 integrin and accumulate in the cerebrospinal fluid in clinically isolated syndrome suggestive of multiple sclerosis onset.

During the pathogenesis of multiple sclerosis (MS), activated B-cells cross the inflamed endothelium of the central nervous system (CNS) to exert their effector functions, probably associated with the action of several adhesion molecules. B-cell mobilization towards the CNS already occurs after the first demyelinating events suggestive of MS, known as clinically isolated syndrome (CIS). However, little is known about the role of these adhesion molecules at this early disease stage.

Using human CD20-transfected murine lymphomatous B cells to evaluate the efficacy of intravitreal and intracerebral rituximab injections in mice.

Purpose: The treatment of primary central nervous system lymphoma (PCNSL) and its subset, primary intraocular lymphoma (PIOL), remains of limited efficiency, and salvage therapies are often used without prior testing in adequate animal models. Most PNCSL/PIOL are aggressive B-cell malignancies. Two animal models that closely mimic the human situation were established to evaluate the efficiency of intravitreal and intracerebral anti-CD20 monoclonal antibody (rituximab) injections.

Accumulation of memory T cells from childhood to old age: central and effector memory cells in CD4(+) versus effector memory and terminally differentiated memory cells in CD8(+) compartment.

Memory T cells can be classified as central memory (T(CM), CD45RA(neg)CCR7(+)), effector memory (T(EM), CD45RA(neg)CCR7(neg)), and terminally differentiated cells (T(TD), CD45RA(+)CCR7(neg)) with different homing and effector capacities. In 101 healthy subjects aged from 5 to 96 years, distinct dynamics were evidenced between circulating CD4(+) and CD8(+) T cell populations. Naive CD4(+) and CD8(+) T cells decreased linearly with age, CD8(+) twice more rapidly.