Interleukin-2 (IL-2) holds promise for the treatment of cancer and autoimmune diseases, but its high-dose usage is associated with systemic immunotoxicity. Differential IL-2 receptor (IL-2R) regulation might impact function of cells upon IL-2 stimulation, possibly inducing cellular changes similar to patients with hypomorphic IL2RB mutations, presenting with multiorgan autoimmunity. Here, we show that sustained high-dose IL-2 stimulation of human lymphocytes drastically reduces IL-2Rβ surface expression especially on T cells, resulting in impaired IL-2R signaling which correlates with high IL-2Rα baseline expression. IL-2R signaling in NK cells is maintained. CD4+ T cells, especially regulatory T cells are more broadly affected than CD8+ T cells, consistent with lineage-specific differences in IL-2 responsiveness. Given the resemblance of cellular characteristics of high-dose IL-2-stimulated cells and cells from patients with IL-2Rβ defects, impact of continuous IL-2 stimulation on IL-2R signaling should be considered in the onset of clinical adverse events during IL-2 therapy.

BACKGROUND: Hybrid immunity to SARS-CoV-2, resulting from both vaccination and natural infection, remains insufficiently understood in paediatric populations, despite increasing rates of breakthrough infections among vaccinated children.
METHODS: We conducted a prospective longitudinal study to investigate the magnitude, specificity, and cytokine profile of antigen-specific T cell responses elicited by breakthrough SARS-CoV-2 infection in a cohort of mRNA-vaccinated children (n = 29) aged 5-11. This longitudinal analysis involved six distinct time points spanning a 16-month period post-vaccination, during which we analysed a total of 159 blood samples. All children who were followed for at least 12 months (n = 26) experienced a breakthrough infection. We conducted cytokine release assays using minimal blood samples, and we verified the cellular origin of these responses through intracellular cytokine staining.
RESULTS: After breakthrough infection, children who had received mRNA vaccines showed enhanced Th1 responses specific to Spike peptides. Additionally, their Spike-specific T cells exhibited a distinctive enrichment of CD4+ IFN-γ+IL10+ cells, a characteristic akin to adults with hybrid immunity. Importantly, vaccination did not impede the development of multi-specific T cell responses targeting Membrane, Nucleoprotein, and ORF3a/7/8 antigens.
CONCLUSIONS: Children, previously primed with a Spike-based mRNA vaccine and experiencing either symptomatic or asymptomatic breakthrough infection, retained the ability to enhance and diversify Th1/IL-10 antigen-specific T cell responses against multiple SARS-CoV-2 proteins. These findings mirror characteristics associated with hybrid cellular immunity in adults, known to confer resistance against severe COVID-19.
BACKGROUND: This study was funded by the National Medical Research Council (NMRC) Singapore (COVID19RF-0019, MOH-000019, MOH-000535, OFLCG19May-0034 and MOH-OFYIRG19nov-0002).

Amyotrophic lateral sclerosis (ALS) represents a rare and potentially fatal neurodegenerative disease. Diverse T-cell subsets could potentially exert diametrically opposite impacts upon ALS development. A two-sample Mendelian randomization (MR) analysis was performed to investigate the correlation between 244 T-cell subsets and ALS risk. Genetic instrumental variables were procured from a standard genome-wide association study (GWAS) that encompassed 244 T-cell subsets in 3757 individuals of European lineage. ALS-related data were collected from a GWAS comprising 20,806 ALS instances and 59,804 European control participants. Multiple sensitivity analyses were performed to verify the robustness of the significant results. Reverse MR analysis was used for delineating the effects of ALS on the characteristics of T-cells. After multiple comparison corrections, 24 out of the 244 subtypes demonstrated a potential association with ALS risk. Significantly, 75% of these associations encompassed the expression of the CD3 on diverse T-cell subtypes, revealing a highly consistent inverse relation to ALS risk. The proportion of T regulatory cells (Tregs) in CD4+ T cells and secreting Tregs in CD4+ T cells demonstrated negative associations with the risk of ALS. CCR7 expression on naive CD4+ T cells and CCR7 expression on naive CD8+ T cells showed positive associations with ALS risk. Certain T-cell subsets, particularly those identified by CD3 expression on terminally differentiated CD8+ T cells, proportions of Tregs, and CCR7 expression, indicated an association with ALS risk. These findings harmonize with and extend previous observational studies investigating the involvement of T lymphocyte subset-induced immunological processes in ALS.

SARS-CoV-2 vaccination in rheumatoid arthritis (RA) patients treated with B cell-depleting drugs induced limited seroconversion but robust cellular response. We aimed to document specific T and B cell immunity in response to vaccine booster doses and breakthrough infection (BTI).
We included 76 RA patients treated with rituximab who received up to four SARS-CoV-2 vaccine doses or three doses plus BTI, in addition to vaccinated healthy donors (HD) and control patients treated with tumor necrosis factor inhibitor (TNFi). We quantified anti-SARS-CoV-2 receptor-binding domain (RBD) Spike IgG, anti-nucleocapsid (NC) IgG, 92 circulating inflammatory proteins, Spike-binding B cells, and Spike-specific T cells along with comprehensive high-dimensional phenotyping and functional assays.
The time since the last rituximab infusion, persistent inflammation, and age were associated with the anti-SARS-CoV-2 RBD IgG seroconversion. The vaccine-elicited serological response was accompanied by an incomplete induction of peripheral Spike-specific memory B cells but occurred independently of T cell responses. Vaccine- and BTI-elicited cellular immunity was similar between RA and HD ex vivo in terms of frequency or phenotype of Spike-specific cytotoxic T cells and in vitro in terms of the functionality and differentiation profile of Spike-specific T cells.
SARS-CoV-2 vaccination in RA can induce persistent effector T-cell responses that are reactivated by BTI. Paused rituximab medication allowed serological responses after a booster dose (D4), especially in RA with lower inflammation, enabling efficient humoral and cellular immunity after BTI, and contributed overall to the development of potential durable immunity.

Evolving knowledge about the tumor-immune microenvironment (TIME) is driving innovation in designing novel therapies against hard-to-treat breast cancer. Targeting the immune components of TIME has emerged as a promising approach for cancer therapy. While recent immunotherapies aim at restoring antitumor immunity, counteracting tumor escape remains challenging. Hence there is a pressing need to better understand the complex tumor-immune crosstalk within TIME. Considering this imperative, this study aims at investigating the crosstalk between the two abundant immune cell populations within the breast TIME-macrophages and T cells, in driving tumor progression using an organotypic 3D in vitro tumor-on-a-chip (TOC) model. The TOC features distinct yet interconnected organotypic tumor and stromal entities. This triculture platform mimics the complex TIME, embedding the two immune populations in a suitable 3D matrix. Analysis of invasion, morphometric measurements, and flow cytometry results underscores the substantial contribution of macrophages to tumor progression, while the presence of T cells is associated with a deceleration in the migratory behavior of both cancer cells and macrophages. Furthermore, cytokine analyses reveal significant upregulation of leptin and RANTES (regulated on activation, normal T Cell expressed and secreted) in triculture. Overall, this study highlights the complexity of TIME and the critical role of immune cells in cancer progression.

Several concerns have been raised about a causal relationship between COVID-19 mRNA-based vaccines and the development of herpes zoster (HZ). We performed a prospective analysis of the Vax-On-Third-Profile study to investigate the incidence of HZ after the third dose of mRNA-BNT162b2 (tozinameran) and its correlation with immune responses. Patients who had received a booster dose and had been actively treated for at least 8 weeks were eligible. Serologic assessment was performed before the third dose of tozinameran (timepoint-1) and 4 weeks later (timepoint-2). We also assessed the incidence of SARS-CoV-2 breakthrough infections at predefined time points. The current analysis included 310 patients, of whom 109 (35.2%) and 111 (35.8%) were being treated with targeted therapies and cytotoxic chemotherapy, respectively. All participants received a third dose of tozinameran between September 26 and October 30, 2021. After a mean follow-up of 17.3 (IQR 15.1-18.4) months, HZ occurred in 8 recipients, for a cumulative incidence of 2.6%, and an incidence rate of 0.310 per person-year (95% CI 0.267-0.333). All HZ cases occurred within 30 days of booster dosing (range 5-29 days), with a median time to onset of 15 (IQR 9-22) days. Among the 7 patients (2.2%) who also contracted a SARS-CoV-2 infection, all cases preceded COVID-19 outbreaks. No instances of complicated HZ were reported. In multivariate analysis, impaired T helper and T cytotoxic cell counts independently correlated with HZ occurrence. These findings provide the first evidence that cancer patients on active treatment have a not negligible risk of developing HZ within 30 days after the third dose of tozinameran. The favorable clinical outcome of all observed cases confirms that protective effects of boosters in reducing the risk of severe COVID-19 outweigh the potential risk of HZ occurrence.

Food allergy is a leading cause of anaphylaxis worldwide. Allergen-specific immunotherapy is the only treatment shown to modify the natural history of allergic disease, but application to food allergy has been hindered by risk of severe allergic reactions and short-lived efficacy. Allergen-derived peptides could provide a solution. PVX108 comprises seven short peptides representing immunodominant T-cell epitopes of major peanut allergens for treatment of peanut allergy.
Pre-clinical safety of PVX108 was assessed using ex vivo basophil activation tests (n = 185). Clinical safety and tolerability of single and repeat PVX108 doses were evaluated in a first-in-human, randomized, double-blind, placebo-controlled trial in peanut-allergic adults (46 active, 21 placebo). The repeat-dose cohort received six doses over 16 weeks with safety monitored to 21 weeks. Exploratory immunological analyses were performed at pre-dose, Week 21 and Month 18 after treatment.
PVX108 induced negligible activation of peanut-sensitised basophils. PVX108 was safe and well tolerated in peanut-allergic adults. There were no treatment-related hypersensitivity events or AEs of clinical concern. The only events occurring more frequently in active than placebo were mild injection site reactions. Exploratory immunological analyses revealed a decrease in the ratio of ST2+ Th2A:CCR6+ Th17-like cells within the peanut-reactive Th pool which strengthened following treatment.
This study supports the concept that PVX108 could provide a safe alternative to whole peanut immunotherapies and provides evidence of durable peanut-specific T-cell modulation. Translation of these findings to clinical efficacy in ongoing Phase 2 trials would provide important proof-of-concept for using peptides to treat food allergy.

BACKGROUND: Although the concept of declined immune function associated with cancer has been accepted extensively, real-world clinical studies focusing on analysis of the peripheral blood immune changes underlying ageing, immunity and cancer are scarce.
METHODS: In this case-control study, we retrospectively analysed 1375 cancer patients and enrolled 275 age and gender matched healthy individuals. Flow cytometry was conducted to assess the immune changes. Further analysis was examined by SPSS 17.0 and GraphPad Prism 9 software.
RESULTS: Cancer patients showed obviously decreased CD3+ T, CD3+CD4+ Th, CD3+CD8+ CTL, CD19+ B, CD16+CD56+ NK cell counts and lower percentage of PD-1 (programmed cell death protein-1, PD-1) positive cells than healthy control (P < 0.0001). For cancer patients, the reference range of circulating percentage of PD-1+CD45+ cells, PD-1+CD3+ T cells, PD-1+CD3+CD4+ Th cells and PD-1+CD3+CD8+ CTL (Cytotoxic T Lymphocyte, CTL) were 11.2% (95% CI 10.8%-11.6%), 15.5% (95% CI 14.7%-16.0%), 15.4% (95% CI 14.9%-16.0%) and 14.5% (95% CI 14.0%-15.5%), respectively. Moreover, the reduction of CD3+ T, CD3+CD4+ Th, CD3+CD8+ CTL, CD19+ B cell counts accompanied with age and stage advancing (P < 0.05). CD16+CD56+ NK cells decreased with stage, but elevated in aged and male cancer patients (P < 0.05). Additionally, the percentage of PD-1 positive cells varied across cancer types, raised with age and stage. Head and neck, pancreatic, gynaecological and lung demonstrated a higher level of the percentage of PD-1 positive cells than melanoma, prostate, and breast cancer (P < 0.05).
CONCLUSIONS: This study provides the reference range of the percentage of PD-1 positive cells on peripheral blood, confirms the decreased immune cells and a series of immune changes accompanying with cancer, expands our real world evidence to better understand the interactions of ageing, cancer and immunity. Moreover, the circulating percentage of PD-1 positive cells shows similar tumor type distribution with tumor mutational burden (TMB), supports that it maybe a potential predictive biomarker for immune checkpoint inhibitor therapy.

Malignant melanoma is a highly immunogenic tumour, and the immune profile significantly influences cancer development and response to immunotherapy. The peripheral immune profile may identify high risk patients. The current study showed reduced levels of CD4+ T cells and increased levels of CD8+ T cells in peripheral blood from malignant melanoma patients compared with controls. Percentages of peripheral CD56dimCD16+ NK cells were reduced and CD56brightCD16-KIR3+ NK cells were increased in malignant melanoma patients. Late stage malignant melanoma was correlated with low levels of CD4+ T cells and high levels of CD56brightCD16-KIR3+ NK cells. Finally, high levels of Tregs in peripheral blood were correlated with poor overall survival and disease-free survival. The results indicate that changes in specific immune cell subsets in peripheral blood samples from patients at the time of diagnosis may be potential biomarkers for prognosis and survival. Further studies will enable clarification of independent roles in tumour pathogenesis.

UNASSIGNED: Immune dysfunction plays a pivotal role in sepsis pathogenesis. Previous studies have revealed the crucial role of T cells and human leukocyte antigen-DR (HLA-DR) in sepsis. However, the function of natural killer (NK) cells remains unclear. This study aimed to investigate whether NK cells are associated with sepsis prognosis. In addition, we aimed to explore the interrelation and influence between NK and other immunological features in patients with sepsis.
UNASSIGNED: This retrospective, observational study included patients with sepsis from two hospitals in mainland China. The clinical characteristics and immune results during the early phase were collected. Patients were classified according to the level of immune cells to analyze the relationship between immunological features and 28-day mortality.
UNASSIGNED: A total of 984 patients were included in this study. Non-survivors were older and had lower levels of lymphocytes, monocytes, NK cells, HLA-DR, and T cells. Patients were classified into eight groups according to their levels of NK cells, HLA-DR, and T cells. Only patients with decreased NK and T cell counts showed a significant increase in 28-day mortality. An increase in CD8+ T cells was correlated with the alleviation of 28-day mortality only among patients with high NK cell levels.
UNASSIGNED: This study provides novel insights into the association between NK cells and 28-day mortality as well as the interrelation between NK cells and other immune cells in sepsis. The relationship between CD8+ T cells and 28-day mortality in sepsis is dependent on NK cell count.