Scandinavian Journal of Immunology最新文献

B cells are essential in the immune system, driving antibody production, cytokine secretion and antigen presentation. Studies in mouse models have illuminated key mechanisms underlying B-cell activation, differentiation, class-switch recombination and somatic hypermutation. However, the extent to which these findings translate to human biology remains unclear. To address this, we developed a human primary B-cell culture system using feeder cells engineered to express CD40L, supplemented with the cytokines BAFF, IL-4 and IL-21. Using a Design of Experiments (DOE) approach, we optimised critical parameters and dissected the individual contributions of each specific factor. Our results reveal that BAFF plays a negligible role, and IL-21 has more subtle effects, whereas CD40L and IL-4 are critical determinants of cell viability, proliferation and IgE class-switching. Furthermore, we find that engineered feeder cells can serve equally well as a source of cytokines, but providing these in purified form increases the flexibility of the system. This platform enables detailed investigation of human B-cell biology, offering insights into intrinsic and extrinsic regulators of antibody responses and providing a foundation for in vitro production of human primary antibodies.

Mast cells have long been recognised for their pivotal role in the development of allergic inflammation. However, their contributions extend far beyond this well-established function. Accumulating evidence supports that mast cells play essential roles in regulating both innate and adaptive immune responses by releasing a diverse array of potent immune mediators and cytokines. Importantly, mast cells are nowadays appreciated to possess the capacity to mount effective host defence responses against a variety of pathogens. One of the most notable features of mast cells is their abundance in mucosal tissues, which serve as primary entry points for many infectious agents, as well as common allergens. This strategic positioning enables mast cells to respond quickly to both harmful pathogens and allergens, making them key players in the body's first line of defence. In this review, we aim to summarise the current understanding of how mast cells contribute to the immune defence against infections. We will explore the mechanisms by which these cells respond to various pathogens and how their activation affects the overall immune response. Furthermore, we will discuss innovative strategies for harnessing mast cell activation to enhance vaccine efficacy. By exploiting the adjuvant properties of mast cell activators, we can potentially improve the quality of vaccination against infectious diseases. This exploration highlights the dual role of mast cells not only in allergic responses but also as vital components in the fight against infections, underscoring their importance in both immunology and therapeutic strategies.

A key mechanism of tumour immune escape from CD8⁺ cytotoxic T lymphocytes occurs via downregulation of NLRC5, an IFNγ-induced transcriptional activator of MHC class-I. As NLRC5 deficiency does not abrogate CD8⁺ T cell development, we investigated whether NLRC5-dependent antitumour immune mechanisms are required for immune surveillance. We studied the development of 3-methylcholanthrene (MCA)-induced endogenous fibrosarcoma in Nlrc5^-/- mice with Nlrc5^+/+ and Rag1^-/- mice serving as controls. Nlrc5^-/- and Rag1^-/- mice showed increased propensity to develop MCA-induced tumours with a higher growth rate compared to Nlrc5^+/+ mice and displayed significantly reduced survival. Tumours from Nlrc5^+/+ and Nlrc5^-/- mice, but not from Rag1^-/- mice, contained necrotic areas and displayed T cell infiltration. Tumour cell lines established from MCA-induced tumours were evaluated for their sensitivity to immune-mediated growth control following implantation into immunocompetent C57BL/6 and immunodeficient Rag1^-/- hosts. Tumours formed by Nlrc5^+/+ tumour cell lines progressed unhindered in C57BL/6 hosts that reflected their immunoedited status, whereas cell lines from Nlrc5^-/- and Rag1^-/- tumours were efficiently controlled, indicating their non-immunoedited status. Proteomic analysis by mass spectrometry followed by pathway analysis revealed enrichment of granzyme-mediated cytolytic pathway in Nlrc5^+/+ tumours that were absent in Nlrc5^-/- tumours, which showed enrichment of humoral and innate immune pathways. Overall, our findings show that NLRC5 is required for robust tumour immune surveillance and tumour immunoediting and that compensatory humoral and innate immune mechanisms activated by the loss of NLRC5 are insufficient for cancer immune surveillance and cancer immunoediting.

Controlling excessive inflammation remains an unmet clinical need, for example, during sepsis or after severe injuries. Platelet-activating factor (PAF) is central in thromboinflammatory processes. However, its role in the interaction of platelets and neutrophils requires further insights. Therefore, we elucidated PAF-related neutrophil activation, including platelet-neutrophil complex (PNC) formation and investigated potential strategies to modulate PAF-related inflammation. For the translation of the PAF-mediated inflammation, we applied an animal-free human ex vivo whole blood model. The neutrophil phenotype, its function, and PNC formation were studied by flow cytometry and platelet-related activity was assessed by light microscopy and aggregometry. PAF induced a rapid and dose-dependent change in neutrophil phenotype, as evidenced by CD10, CD11b, and CD66b upregulation and CD62L downregulation. Moreover, PAF increased the generation of reactive oxygen species (ROS), phagocytic activity and PNC formation. Interestingly, PNCs displayed significantly enhanced ROS formation and phagocytosis compared to neutrophils without attached platelets, whereas these differences were not observed regarding phenotype changes. Furthermore, the findings were confirmed in a clinically relevant ex vivo whole blood model of lipopolysaccharide- or PAF-driven inflammation. In summary, the present study elucidates PAF-driven effects on neutrophils and their interaction with platelets. The findings might help in developing therapeutic approaches to modulate PAF-related thromboinflammation, for example, during sepsis.

Burkitt lymphoma (BL) is an aggressive non-Hodgkin B-cell lymphoma characterised by chromosomal translocations involving the MYC gene, leading to its overexpression and driving uncontrolled proliferation. BL is categorised into endemic, sporadic, and immunodeficiency-associated subtypes, each with distinct clinical and epidemiological features. TSPAN32, a member of the tetraspanin family, plays a key role in B cell development and immune regulation. In this study, we investigated the regulation of TSPAN32 expression in BL subtypes. Our results show that TSPAN32 expression is significantly downregulated in endemic, sporadic, and HIV-associated BL. Notably, this downregulation is independent of Epstein-Barr virus (EBV) infection, as no significant differences in TSPAN32 expression were observed between EBV-positive and EBV-negative BL clones. Functional studies revealed that overexpression of a wild-type ID3 gene, a known repressor of TCF3, and knockdown of TCF3, both led to a significant upregulation of TSPAN32, particularly in BL41 and Daudi cells, which harbour ID3 mutations. Supporting this, ChIP-seq analysis identified TCF3 binding peaks on the TSPAN32 gene, providing mechanistic evidence of its regulation by TCF3. These findings shed light on the complex transcriptional network regulating TSPAN32 and its dysregulation in BL. Overall, our study suggests that TSPAN32 may serve as both a biomarker and a potential therapeutic target for this disease.

The lack of diagnostic and monitoring tools for postsurgical immunological complications such as systemic inflammation can contribute to a poor outcome despite modern intensive care. The need for reliable immune monitoring has been emphasised. Polymorphonuclear leukocytes (PMNs) play an important role in postsurgical inflammation. A subgroup of PMNs is particularly interesting, because they are released shortly after (iatrogenic) trauma: immature PMNs, characterised by, for example, their low CD10 expression. Therefore, we investigated the role of CD10^low PMNs in a non-interventional exploratory study by including patients undergoing scheduled, highly standardised cardiac surgery with extracorporeal circulation. We were able to demonstrate that the number of CD10^low PMNs released shortly after the beginning of surgery correlated with different fluid phase markers of inflammation and organ damage postsurgically. Among these parameters were CRP, IL-6, NGAL, CK-MB, and troponin-T. Noteworthy, the amount of CD10^low PMNs increased as early as 24 h before these well-established markers, suggesting superiority of CD10^low PMNs as an early diagnostic marker. Comparing CD10^low immature PMNs with CD10^high mature PMNs revealed potential involved mechanisms, including lower CD11b expression and a significant decrease in the formation of platelet-neutrophil complexes (PNCs) by CD10^low PMNs. In conclusion, we propose CD10^low PMNs as a potential early cellular biomarker to assess the postsurgical inflammatory response. In comparison to clinically established markers like CRP or IL-6 and scoring systems such as the SOFA-Score, CD10^low PMNs reflect a potential candidate for future immune monitoring to determine the risk of excessive inflammation and organ impairment more rapidly.

Distinct from the pulmonary circulation, the human respiratory mucosa is supplied by highly responsive, superficial, systemic microcirculations. In the early symptomatic phase of mucosal infections, circulating peptides-proteins of all sizes are released just beneath the epithelium and will soon appear on the mucosal surface. The traditional view is that mucosal injury must be involved in this plasma exudation process. However, well-controlled human in vivo observations demonstrate that the inflammatory plasma exudation response reflects non-injurious physiologic microvascular-epithelial cooperation. Crucially, although plasma exudation brings unfiltered plasma solutes without size restriction to the mucosal surface this occurs without reducing the protective epithelial barrier against inhaled molecules. Plasma exudation starts early and increases until viral or bacterial infections resolve. Plasma exudation therefore has the potential to slow down, or even prevent, progression to pneumonia and beyond. Plasma exudation would boost efficacy of a mature adaptive immunity by delivering circulating pathogen-neutralising antibodies undiluted to infection spots in the upper airways. Early mucosal infections would thus be dampened and development of lower airway infections prevented. Inferentially, this explains how treatment with vaccines still allows upper airway infections but prevent severe respiratory disease with alveolar and pulmonary circulation injury. Plasma exudation may also contribute to real-life protection against severe influenza/Covid-19 in airway mucosal diseases that exhibit plasma exudation hyperresponsiveness. Such hyperresponsiveness is inducible indicating feasibility of finding future treatments that increase the mucosal innate and adaptive immunity. Altogether, the present synthesis of literature suggests that plasma exudation is an important component of human respiratory mucosal antimicrobial immunity.

Common variable immunodeficiency disorders (CVID) are characterized by hypogammaglobulinemia and increased susceptibility to infections. However, non-infectious comorbidities (NICM) are also frequent manifestations of the disease. We search for distinctive immunophenotypes in CVID patients with NICM. Data were obtained from the clinical records and laboratory analyses of 42 CVID patients. Descriptive statistics, median comparisons, bivariate and multivariate analysis were performed. Median comparison of the immunological variables among patients with or without NICM revealed significant decreased levels of serum IgG, percentages of naïve CD4⁺ and CD8⁺ T cells, total B cells and CD56^dim NK cells in peripheral blood from CVID patients with NICM together with an increase in the percentages of effector memory (EM) CD4⁺ and terminally differentiated effector memory (EMRA) CD8⁺ T cells. By using logistic regressions, we determined the likelihood of exhibiting blood immunological abnormalities in patients with NICM vs. those without NICM. Finally, discriminant analyses and ROC curves established that percentages of CD4⁺ EM T cells and CD8⁺ EMRA T cells > 47.4% and 40.2% from the total CD4⁺ or CD8⁺ T cells, respectively, might be associated with NICM in CVID. These differences were also observed in CVID patients with Polyclonal lymphocytic infiltration. These data suggest subpopulations of effector T cells as potential biomarkers of NICM in CVID. Prospective studies are needed to determine the usefulness of our findings in the prognosis of CVID.

Primary immunodeficiency disorders (PIDDs) comprise a heterogeneous group of genetic conditions characterised by recurrent infections, immune dysregulation and increased susceptibility to malignancies. While clinical evaluation remains essential for diagnosis, genetic testing plays a pivotal role in confirming the diagnosis and guiding management. This cross-sectional study evaluates the diagnostic yield and clinical utility of targeted gene panel testing in patients with a strong clinical suspicion of PIDDs, within the framework of the Jeffrey Modell Foundation's 'Jeffrey's Insights' programme. Between 2022 and 2024, 104 patients without a prior genetic diagnosis were evaluated at the Department of Paediatric Allergy and Clinical Immunology, Başakşehir Çam and Sakura City Hospital, Türkiye. In 72 of 104 patients, the identified variants were consistent with clinical phenotypes. Pathogenic or likely pathogenic variants were identified in 41.3% of patients, increasing to 57.7% when including variants of uncertain significance (VUS) with high CADD scores. Genetic findings prompted reclassification of International Union of Immunological Societies (IUIS) categories in 25% of cases. Autosomal recessive inheritance and parental consanguinity were notable, reflecting regional genetic patterns. Failure to thrive and low switched memory B cell percentages were significantly associated with confirmed genetic diagnoses, while food allergy, viral skin infections and eczema were more common in genetically undiagnosed patients. These findings support the clinical value of targeted gene panels as an effective, accessible and informative tool in the diagnosis and classification of PIDDs, enhancing precision in patient care and enabling tailored therapeutic strategies.