Immunology Studies Research Articles

Boosting human immunology: harnessing the potential of immune organoids.

Studying the human immune system in vivo is challenging and often not possible. Therefore, most human immunology studies have been predominantly confined to peripheral blood analyses, which by themselves have inherent limitations, as many immune reactions take place within tissues. For example, potent antibody responses that contribute to fighting infections and provide protection following vaccination require cellular interactions between B cells and T cells in specialized micro-anatomical structures called germinal centers, which are found in secondary lymphoid organs such as spleen, lymph nodes, and tonsils. Thus, there is a clear demand for novel enhanced experimental systems that faithfully recapitulate the intricate dynamics of the human immune system as much as possible. In this review, we discuss recent advances in versatile human tonsil/adenoid tissue-based ex vivo immune organoid cultures as well as related cancer and autoimmunity-focused experimental setups. These systems have been implemented as translational immunology platforms for in-depth analyses of human B and T cell-mediated immune responses, thereby facilitating mechanistic studies as well as drug and vaccine testing in a human-first approach.

ATAC-Seq Library Preparation of Murine Bone Marrow-Derived Neutrophils.

Assay for Transposase-Accessible Chromatin with sequencing (ATAC-seq) is a powerful, high-throughput technique for assessing chromatin accessibility and understanding epigenomic regulation. Neutrophils, as a crucial leukocyte type in immune responses, undergo substantial chromatin architectural changes during differentiation and activation, which significantly impact the gene expression necessary for their functions. ATAC-seq has been instrumental in uncovering key transcription factors in neutrophil maturation, revealing pathogen-specific epigenomic signatures, and identifying therapeutic targets for autoimmune diseases. However, neutrophils' sensitivity to the external milieu complicates high-quality ATAC-seq data production. Here, we propose a scalable protocol for preparing ATAC-seq libraries from rodent bone marrow-derived neutrophils, featuring improved immunomagnetic separation to ensure optimal cell viability and high-quality libraries. The vital elements impacting the library quality and optimization principles for methodological extension are discussed in detail. This protocol will support the researchers who are willing to study the chromatin architecture and epigenomic reprogramming of neutrophils, advancing studies in basic and clinical immunology.

A Current Perspective of Medical Informatics Developments for a Clinical Translation of (Non-coding)RNAs and Single-Cell Technologies.

The journey from laboratory research to clinical practice is marked by significant advancements in the fields of single-cell technologies and non-coding RNA (ncRNA) research. This convergence may reshape our approach to personalized medicine, offering groundbreaking insights and treatments in various clinical settings. This chapter discusses advancements in (nc)RNAs in the clinics, innovations in single-cell technologies and algorithms, and the impact on actual precision medicine, showing the integration of single-cell and ncRNA research can have a tangible impact on precision medicine. Case studies in Oncology, Immunology, and other fields demonstrate how these technologies can guide treatment decisions, tailor therapies to individual patients, and improve outcomes. This approach is particularly potent in addressing diseases with high inter- and intra-tumor heterogeneity. The final sections address standardization, data integration, and analysis challenges because the complexity and volume of data generated by single-cell and ncRNA research poses significant challenges. Medical Informatics is not just a support tool but could be seen as a pivotal component in advancing clinical applications of single-cell and ncRNA research by bridging the gap between bench and bedside. The future of personalized medicine depends on our ability to harness the power of these technologies, and Medical Informatics in combination with ncRNA and single-cell technologies may stand at the forefront of this endeavor.

Effect of M6A methylation on T cell homeostasis

Abstract. The m6A methylation modification is a prevalent form of RNA modification in organisms, exerting its influence on gene expression. In recent years, there has been a gradual elucidation of the relationship between the physiological functions of m6A methylation modification and immune regulation, obesity, as well as malignant diseases such as tumors. Consequently, the study of m6A methylation modification has emerged as a focal point in current molecular biology research. This research focuses on the interaction between immune system homeostasis and m6A methylation alteration and the human immune system. It also describes the significant effects of three crucial regulatory proteins required for m6A methylation modification on the growth and differentiation of immune cells (T cells). This research provides a novel direction for future studies in immunology and disease pathology. However, there are still some research difficulties, for instance, a number of methyltransferases, demethylases, and recognition proteins control the alteration of m6A methylation, and the interaction and regulatory network among these proteins are not clear, so future research can focus on this direction.

Fish Cell Spheroids, a Promising In Vitro Model to Mimic In Vivo Research: A Review.

In vitro cell culture systems serve as instrumental platforms for probing biological phenomena and elucidating intricate cellular mechanisms. These systems afford researchers the opportunity to scrutinize cellular responses within a regulated environment, thereby circumventing the ethical and logistical challenges associated with in vivo experimentation. Three-dimensional (3D) cell cultures have emerged as a viable alternative to mimic in vivo environments. Within this context, spheroids are recognized as one of the most straightforward and efficacious models, presenting a promising substitute for conventional monolayer cultures. The application of 3D cultures of fish cells remains limited, focusing mainly on physiological and morphological characterization studies. However, given the capacity of spheroids to emulate in vivo conditions, researchers are exploring diverse applications of these 3D cultures. These include eco-toxicology, immunology, drug screening, endocrinology, and metabolism studies, employing a variety of cell types such as fibroblasts, hepatocytes, embryonic cells, gonadal cells, gastrointestinal cells, and pituitary cells. This review provides a succinct overview, concentrating on the most frequently employed methods for generating fish cell spheroids and their applications to date. The aim is to compile and highlight the significant contributions of these methods to the field and their potential for future research.

Diphencyprone reduces the CD8+ lymphocytes and IL-4 and enhences IgG2a/IgG1 ratio in pathogenicity of acute leishmania major infection in BALB/c mice

BackgroundThe exact role of different immune cells and cytokines in control or promotion of intracellular growth of leishmania has still remained a controversial topic. The aim of the present study was to study effects of cellular changes and relevant cytokines in cell mediated immunity by diphencyprone (DCP) in pathogenicity of acute L.major infection in BALB/c mice. Methods45 healthy female BALB/c mice were injected with L. major promastigotes under the base of tail. The mice were randomly divided to three groups of 15 mice: (1) control group without any treatment. (2) acetone group: Acetone was applied topically on the cutaneous lesions weekly and (3) DCP group: DCP was applied topically on the cutaneous lesions with increasing concentrations to induce local allergy. The mice were followed by the end of eighth week, and then macroscopic changes, histopathology, immunology studies, and organ parasite burden were determined. ResultsIn DCP group, in comparison to other groups the ulcer size and parasite burden in ulcer site and spleen increased, significantly. There was a deep lymphohistiocytic infiltration in the ulcer site. Total IgG, IgG1, and IgG2a levels as well as IgG2a/IgG1 ratio and intracellular IFN-gamma in CD8+ lymphocytes were significantly higher. IL4 and T CD8+ lymphocytes were significantly lower in DCP group. The IgG2a/IgG1 ratio was more than 1 in all groups. ConclusionOur findings demonstrated that DCP reduced the CD8+ lymphocytes and IL-4 production. In spite of increased IgG2a/IgG1 ratio, the parasite burden and inflammation severity increased in infected mice. The results can show the pivotal role of CD8+ lymphocytes in conjunction with Th1 lymphocytes in the control of acute leishmania infection in mice.

Cytometry masked autoencoder: An accurate and interpretable automated immunophenotyper

Single-cell cytometry data are crucial for understanding the role of the immune system in diseases and responses to treatment. However, traditional methods for annotating cytometry data face challenges in scalability, robustness, and accuracy. We propose a cytometry masked autoencoder (cyMAE), which automates immunophenotyping tasks including cell type annotation. The model upholds user-defined cell type definitions, facilitating interpretability and cross-study comparisons. The training of cyMAE has a self-supervised phase, which leverages large amounts of unlabeled data, followed by fine-tuning on specialized tasks using smaller amounts of annotated data. The cost of training a new model is amortized over repeated inferences on new datasets using the same panel. Through validation across multiple studies using the same panel, we demonstrate that cyMAE delivers accurate and interpretable cellular immunophenotyping and improves the prediction of subject-level metadata. This proof of concept marks a significant step forward for large-scale immunology studies.

Success of Immunopathogenetic Therapy for Management of Congenital Ichthyosis, Combined Form, in a Child: Rare Clinical Case

Background. Congenital ichthyosis (CI) is relating to the group of clinical and genetically heterogeneous severe genodermatoses. SAM syndrome is included in classification of CI syndromic forms. Defects in the desmoplakin (DSP) and desmoglein 1 (DSG1) genes are the prime cause of disease. Impaired function of encoded proteins leads to desmosomal anomalies and disease symptoms. Comorbid atopic syndrome becomes the major cause of diagnostic mistakes. Patients are observed continuously with diagnosis “Atopic dermatitis (AD) torpid to standard treatment methods”. Clinical case description. This article describes a rare case of a boy with severe AD. Despite the chronic dermatosis several systemic disorders were revealed during examination: short stature, protein-energy malnutrition, adrenal insufficiency, juvenile polyarthritis, vitamin D deficiency, onychodystrophy, dysmorphic disorders. Molecular genetic study conducted via high-throughput sequencing followed by validation with Sanger sequencing has revealed two genetic variants: novel variant chr18:28934543G>T in the DSG1 gene in the heterozygous state and pathogenic variant chr5:157468728C>A in the NIPAL4 gene in the homozygous state. As a result, the final diagnosis was established: “SAM syndrome. Congenital ichthyosiform erythroderma”. Flow cytometry immunology study has shown dominant immunological profile of Th17-, and Thact-lymphocyte proliferation. The immunobiological therapy with IL-17A inhibitor, secukinumab, was initiated. Clinical efficacy was evaluated via ISS (Ichthyosis Severity Index), CDLQI (Children’s Dermatology Life Quality Index), pruritus numerical rating scale. ISS was 5.8 points, pruritus scale — 9, CDLQI — 24 at therapy initiation. Improvement in the skin condition was observed after a month of therapy. ISS was 1.2 points, pruritus scale — 2, CDLQI — 4 6 months after the therapy initiation. Conclusion. The diagnosis of a child with combined form of CI made it possible to change the management strategy, to prescribe pathogenetically justified targeted immunobiological therapy, and to achieve significant improvement in the child's health and quality of life, which does not differ from healthy peers.

Systematic analysis of human colorectal cancer scRNA-seq revealed limited pro-tumoral IL-17 production potential in gamma delta T cells

Gamma delta T cells play a crucial role in anti-tumor immunity due to their cytotoxic properties. However, the role and extent of γδ T cells in production of pro-tumorigenic interleukin-17 (IL-17) within the tumor microenvironment of colorectal cancer (CRC) remains controversial. In this study, we re-analyzed nine published human CRC whole-tissue single-cell RNA sequencing datasets, identifying 18,483 γδ T cells out of 951,785 total cells, in the neoplastic or adjacent normal tissue of 165 human CRC patients. Our results confirm that tumor-infiltrating γδ T cells exhibit high cytotoxicity-related transcription in both tumor and adjacent normal tissues, but critically, none of the γδ T cell clusters showed IL-17 production potential. We also identified various γδ T cell subsets, including poised effector-like T cells, tissue-resident memory T cells, progenitor exhausted-like T cells, and exhausted T cells, and noted an increased expression of cytotoxic molecules in tumor-infiltrating γδ T cells compared to their normal area counterparts. We proposed anti-tumor γδ T effector cells may arise from tissue-resident progenitor cells based on the trajectory analysis. Our work demonstrates that γδ T cells in CRC primarily function as cytotoxic effector cells rather than IL-17 producers, mitigating the concerns about their potential pro-tumorigenic roles in CRC, highlighting the importance of accurately characterizing these cells for cancer immunotherapy research and the unneglectable cross-species discrepancy between the mouse and human immune system in the study of cancer immunology.

Establishment and identification of the head kidney cell line of yellowfin seabream (Acanthopagrus latus) and its application in a virus susceptibility study

The yellowfin seabream (Acanthopagrus latus) is a crucial marine resource owing to its economic significance. Acanthopagrus latus aquaculture faces numerous challenges from viral diseases, but a robust in-vitro research model to understand and address these threats is lacking. Therefore, we developed a novel A. latus cell line from head kidney cells called ALHK1. This study details the development, characterisation, and viral susceptibility properties of ALHK cells. This cell line primarily comprises fibroblast-like cells and has robust proliferative capacity when cultured at 28 °C in Leibovitz's L-15 medium supplemented with 10–20% foetal bovine serum. It exhibited remarkable stability after more than 60 consecutive passages and validation through cryopreservation techniques. The specificity of the ALHK cell line's origin from A. latus was confirmed via polymerase chain reaction (PCR) amplification of the cytochrome B gene, and a chromosomal karyotype analysis revealed a diploid count of 48 (2n = 48). Furthermore, the lipofection-mediated transfection efficiency using the pEGFP-N3 plasmid was high, at nearly 40%, suggesting that ALHK cells could be used for studies involving exogenous gene manipulation. In addition, ALHK cells displayed heightened sensitivity to the large mouth bass virus (LMBV), substantiated through observations of cytopathic effects, quantitative real-time PCR, and viral titration assays. Finally, the response of ALHK cells to LMBV infection resulted in differentially expressed antiviral genes associated with innate immunity. In conclusion, the ALHK cell line is a dependable in-vitro platform for elucidating the mechanisms of viral diseases in yellowfin seabream. Moreover, this cell line could be valuable for immunology, vaccine development, and host-pathogen interaction studies.

Production of a monoclonal antibody specific to the IgM heavy chain of Asian seabass (Lates calcarifer Bloch, 1790) and its application in assessing health status following vaccination and challenges with Flavobacterium covae and Streptococcus iniae

Immunoglobulin M (IgM) shows potential as a significant immunological marker in Asian seabass (Lates calcarifer), accentuating the importance of developing specific monoclonal antibodies (mAbs) for immunological studies. In this study, we investigated the antigenicity of the IgM heavy chain (IgMH), particularly the Cμ3 region of IgMH (IgMHCμ3), and synthesized a peptide for anti-IgMHCμ3 mAb production. The synthesized peptide was used to generate a specific mAb in rabbits. The produced mAb demonstrated high specificity and affinity for Asian seabass IgMH, as confirmed through indirect ELISA, Western blot analysis, indirect immunofluorescence assay (IIFAT) and flow cytometry analysis. In addition, an indirect ELISA was developed and optimized to measure anti-Flavobacterium covae and anti-Streptococcus iniae antibody titers in Asian seabass serum. The monoclonal antibody (mAb) was subsequently used to assess the health status of Asian seabass post-vaccination and challenge with these pathogens, demonstrating its potential as a valuable tool for immunological studies and health assessments in Asian seabass. Vaccination and postchallenge fish exhibited a pronounced increase in specific antibodies and total serum IgM and IgM+ cell populations. Thus, this study establishes a foundational platform for using the anti-IgMHCμ3 mAb as an essential tool for evaluating and understanding the immune responses and health status of Asian seabass, especially in the context of bacterial infections and vaccinations, and paves the way for more studies in fish immunology.

The future of amphibian immunology: Opportunities and challenges

Historically, amphibians have been essential to our understanding of vertebrate biology and animal development. Because development from egg to tadpole to adult frog can be directly observed, amphibians contributed greatly to our understanding of not only vertebrate animal development but also the development of the immune system. The South African clawed frog (Xenopus laevis) has been key to many of these findings. For example, using Xenopus as a model, the comparative immunology community learned about the contribution of hematopoietic stem cells to development of the immune system and about the diversity of antibodies, B cells, T cells and antigen presenting cells. Amphibians offer many advantages as unique potential model systems to address questions about immune skin interactions, host responses to mycobacteria, the diverse functions of interferons, and immune and mucosal interactions. However, there are also many challenges to advance the research including the lack of specific reagents and well annotated genomes of diverse species. While much is known, many important questions remain. The aim of this short commentary is to look to the future of comparative immunology of amphibians as a group. By identifying some important questions or “information-deficit” areas of research, I hope to pique the interest of younger developing scientists and persuade funding agencies to continue to support comparative immunology studies including those of amphibians.

Senso-immunology: the hidden relationship between sensory system and immune system.

The primary sensory neurons involved in pain perception express various types of receptor-type ion channels at their nerve endings. These molecules are responsible for triggering neuronal excitation, translating environmental stimuli into pain signals. Recent studies have shown that acute nociception, induced by neuronal excitation, not only serves as a sensor for signaling life-threatening situations but also modulates our pathophysiological conditions. This modulation occurs through the release of neuropeptides by primary sensory neurons excited by nociceptive stimuli, which directly or indirectly affect peripheral systems, including immune function. Senso-immunology, an emerging research field, integrates interdisciplinary studies of pain and immunology and has garnered increasing attention in recent years. This review provides an overview of the systemic pathophysiological functions regulated by receptor-type ion channels, such as transient receptor potential (TRP) channels in primary sensory neurons, from the perspective of senso-immunology.

Systematic Analysis of Human Colorectal Cancer scRNA-seq Revealed Limited Pro-tumoral IL-17 Production Potential in Gamma Delta T Cells.

Gamma delta (γδ) T cells play a crucial role in anti-tumor immunity due to their cytotoxic properties. However, the role and extent of γδ T cells in production of pro-tumorigenic interleukin- 17 (IL-17) within the tumor microenvironment (TME) of colorectal cancer (CRC) remains controversial. In this study, we re-analyzed nine published human CRC whole-tissue single-cell RNA sequencing (scRNA-seq) datasets, identifying 18,483 γδ T cells out of 951,785 total cells, in the neoplastic or adjacent normal tissue of 165 human CRC patients. Our results confirm that tumor-infiltrating γδ T cells exhibit high cytotoxicity-related transcription in both tumor and adjacent normal tissues, but critically, none of the γδ T cell clusters showed IL-17 production potential. We also identified various γδ T cell subsets, including Teff, TRM, Tpex, and Tex, and noted an increased expression of cytotoxic molecules in tumor-infiltrating γδ T cells compared to their normal area counterparts. Our work demonstrates that γδ T cells in CRC primarily function as cytotoxic effector cells rather than IL-17 producers, mitigating the concerns about their potential pro-tumorigenic roles in CRC, highlighting the importance of accurately characterizing these cells for cancer immunotherapy research and the unneglectable cross-species discrepancy between the mouse and human immune system in the study of cancer immunology.

The neurobiological mechanism underlying ketamine’s rapid-acting antidepressant effect

Depression is one of the most common disabling mental disorders. However, first-line treatments for depression are typically slow-acting. Ketamine, a glutamatergic modulator with rapid antidepressant effects, has proven effective in treating both refractory depression and suicidal tendencies. The neurobiological mechanisms underlying the effects of antidepressants have become a research hotspot; yet, the exact processes remain unclear. Brain imaging studies have provided important evidence from macroscopic perspectives, such as brain structure and function, while biochemical studies have made significant discoveries from microscopic perspectives, including proteomics and genomics. Previous reviews have summarized a broad range of biomarkers related to the ketamine response, encompassing studies in imaging, electrophysiology, metabolism, immunology, genetics, and neurotrophy. In this review, we systematically summarize a number of potential biomarkers for predicting and modulating the efficacy of ketamine, from both macroperspectives (such as neuroimaging and neuroelectrophysiological markers) and microperspectives (such as neurobiochemical and genetic markers). Although research in this area is still in its infancy, these biomarkers can help clinicians identify whether ketamine intervention is needed for treatment-resistant depression, thereby reducing the burden on patients and society. However, the majority of biomarkers are still in the preclinical exploratory stage, and existing findings are limited. To realize the clinical application of these biomarkers, future studies should combine biomarkers of different types to investigate the relationships and interactions between them. This approach aims to optimize clinical outcomes by enhancing the involvement of biological targets in new models.

Integrating functional metagenomics to decipher microbiome-immune interactions.

Microbial metabolites can be viewed as the cytokines of the microbiome, transmitting information about the microbial and metabolic environment of the gut to orchestrate and modulate local and systemic immune responses. Still, many immunology studies focus solely on the taxonomy and community structure of the gut microbiota rather than its functions. Early sequencing-based microbiota profiling approaches relied on PCR amplification of small regions of bacterial and fungal genomes to facilitate identification of the microbes present. However, recent microbiome analysis methods, particularly shotgun metagenomic sequencing, now enable culture-independent profiling of microbiome functions and metabolites in addition to taxonomic characterization. In this review, we showcase recent advances in functional metagenomics methods and applications and discuss the current limitations and potential avenues for future development. Importantly, we highlight a few examples of key areas of opportunity in immunology research where integrating functional metagenomic analyses of the microbiome can substantially enhance a mechanistic understanding of microbiome-immune interactions and their contributions to health and disease states.

Germline NQO1c.559C>T as a biomarker of genetic susceptibility to immune checkpoint blockade resistance.

8537 Background: Tobacco is the main risk factor for developing lung cancer. Yet, some heavy smokers do not develop cancer while others do at young ages. The study of cancer immunology has led to the surge of immune checkpoint blockade (ICB), which transformed the treatment landscape of cancer pts. NQO1 has been associated with extreme phenotypes of high risk for the development of tobacco-induced NSCLC and with poor survival outcomes for xerographs. Development of biomarkers for ICB has been mainly focused on tumor-related factors while genetic susceptibility of the host has been poorly explored to date and some evidence suggests that genetic dysregulation may enables immune escape. Methods: From June 2016 to January 2023, 326 NSCLC pts from two main University Hospitals of Malaga (Spain) receiving ICB were prospectively enrolled, blood samples were gathered. We selected a representative set of 60 consecutive pts for exome sequencing to characterize the germline contribution to resistance (progression within the first 6 months of treatment). PBMC DNA was extracted and prepared for exome sequencing. Raw sequencing data was processed and aligned to a reference genome using BWA. Base recalibration, germline variant calling and variant filtering was performed through GATK. Survival probabilities were estimated with the Kaplan-Meier method and compared using the log-rank test. We explored the lung cancer related genes among our results. Results: Median age at diagnosis of 64 (54-85). 76,6% were men. 44/60 (73,3%) were adenocarcinoma (ADC), PD-L1≥1% in 55% of patients, 22% shown PD-L≥50%. 78% had advanced disease at diagnosis. 65% received ICB in combination with chemotherapy. We found NQO1c.559C>T in 46,6% of pts (28/60). The variation was not associated with survival outcomes in the multivariant analysis (p>0.05) but with poor OS for non-ADC histology (19.7m vs 6m for mutated and WT, respectively; p<0.01). In addition, we found 26 germline variants associated with OS and PFS, and 52 variants with response to ICB. The variants were missense or involved a stop gain/loss. Conclusions: Exome sequencing analysis of germline variants could be a suitable methodology to identify subrogated biomarkers of immune resistance in NSCLC patients. NQO1c.559C>T might help to identify poor prognosis non-ADC pts in the ICB setting.

The Promise of a Pointillist Perspective for Comparative Immunology.

Most studies in comparative immunology involve investigations into the detailed mechanisms of the immune system of a nonmodel organism. Although this approach has been insightful, it has promoted a deep understanding of only a handful of species, thus inhibiting the recognition of broad taxonomic patterns. Here, we call for investigating the immune defenses of numerous species within a pointillist framework, that is, the meticulous, targeted collection of data from dozens of species and investigation of broad patterns of organismal, ecological, and evolutionary forces shaping those patterns. Without understanding basic immunological patterns across species, we are limited in our ability to extrapolate and/or translate our findings to other organisms, including humans. We illustrate this point by focusing predominantly on the biological scaling literature with some integrations of the pace of life literature, as these perspectives have been the most developed within this framework. We also highlight how the more traditional approach in comparative immunology works synergistically with a pointillist approach, with each approach feeding back into the other. We conclude that the pointillist approach promises to illuminate comprehensive theories about the immune system and enhance predictions in a wide variety of domains, including host-parasite dynamics and disease ecology.

MAIT cell-MR1 reactivity is highly conserved across multiple divergent species

Mucosal-associated invariant T (MAIT) cells are a subset of unconventional T cells that recognize small molecule metabolites presented by MHC-I related protein 1 (MR1), via an αβ T cell receptor (TCR). MAIT TCRs feature an essentially invariant TCR α-chain, which is highly conserved between mammals. Similarly, MR1 is the most highly conserved MHC-I like molecule. This extreme conservation, including the mode of interaction between the MAIT TCR and MR1, has been shown to allow for species-mismatched reactivities unique in T cell biology thereby allowing the use of selected species-mismatched MR1–antigen (MR1–Ag) tetramers in comparative immunology studies. However, the pattern of cross-reactivity of species-mismatched MR1–Ag tetramers in identifying MAIT cells in diverse species has not been formally assessed. We developed novel cattle and pig MR1–Ag tetramers and utilized these alongside previously developed human, mouse and pig-tailed macaque MR1–Ag tetramers to characterize cross-species tetramer reactivities. MR1–Ag tetramers from each species identified T cell populations in distantly related species with specificity that was comparable to species-matched MR1–Ag tetramers. However, there were subtle differences in staining characteristics with practical implications for the accurate identification of MAIT cells. Pig MR1 is sufficiently conserved across species that pig MR1–Ag tetramers identified MAIT cells from the other species. However, MAIT cells in pigs were at the limits of phenotypic detection. In the absence of sheep MR1–Ag tetramers, a MAIT cell population in sheep blood was identified phenotypically, utilizing species-mismatched MR1–Ag tetramers. Collectively, our results validate the use and limitations of species-mismatched MR1–Ag tetramers in comparative immunology studies.

First lung infection permanently enlarges LN and enhances new T cell responses

Abstract Humans experience about four respiratory infections per year. Immunology and vaccinology studies in mice are typically performed in naïve specific pathogen free (SPF) animals responding to their very first respiratory challenge. We found that the first respiratory infection induces lifelong enlargement of lung-draining mediastinal LNs. Furthermore, infection-experienced medLNs supported better naïve T cell surveillance and effector responses to new unrelated infections and engendered more biased accumulation and memory establishment within the lung. Moreover, we observed that weight loss induced by influenza infection was substantially reduced in mice that had recovered from a previous unrelated respiratory viral challenge. These data show that the lack of infectious history in SPF mice alters their immune response to lung infections. Preclinical vaccination and immunology studies should consider the previous infectious experience of the model organism.