Natural Killer Research Articles

In-depth immune profiling of a patient with immunodeficiency, centromeric instability, and facial anomalies syndrome type 2 caused by a novel mutation in ZBTB24.

Immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome is a rare genetic disorder characterized by immunodeficiency and chromosomal instability. Mutations in DNA methylation genes such as DNMT3B (ICF1), ZBTB24 (ICF2), CDCA7 (ICF3), and HELLS (ICF4) cause ICF. ICF2 syndrome has been previously described, yet the extent of its clinical presentation and immunological consequences needs to be further elucidated. We describe a patient with a novel homozygous mutation in ZBTB24 (Q375Hfs*3). While infections with extracellular pathogens are frequent in other reported ICF2 patients, our patient also displays infections by intracellular pathogens. At the molecular level, we showed that the novel mutation results in a truncated ZBTB24 protein that disrupts its function in DNA methylation. We thoroughly characterized the immunological consequences of ZBTB24 deficiency using mass cytometry coupled with state-of-the-art computational methods. Our analysis revealed reduced frequencies of natural killer cells and class-switched memory B cell populations in our patient, along with low levels of the immunoglobulin isotypes IgG4 and IgM. Despite observing normal cell frequencies within the T and myeloid compartments, the clinical presentation of this patient suggests a functional defect in immune cells known to be critical to combat intracellular pathogens. Overall, this study expands the clinical and immunological features of ZBTB24 deficiency and highlights the importance of ZBTB24 to the human immune response.

Current status of xenotransplantation from an immunobiological standpoint.

Xenotransplantation, which involves the transplantation of organs, tissues, or cells from animals into humans, is emerging as a promising solution to mitigate the global shortage of human donor organs. Nonetheless, its clinical application is constrained by significant immunological and physiological barriers-most notably, the rapid rejection of xenografts by both the innate and adaptive immune systems. This review discusses critical immunological challenges such as natural antibodies, complement activation, coagulation dysregulation, and cellular immune responses mediated by T cells, macrophages, and natural killer cells. Advances in genetic engineering-such as the development of multi-knockout pigs that lack major xenoantigens and the transgenic expression of human regulatory proteins-have considerably prolonged xenograft survival in preclinical models. Moreover, approaches such as mixed hematopoietic chimerism, thymic transplantation, cell-based therapies, and synthetic particle-based delivery hold promise for inducing immune tolerance. Innovations in pharmacological immunosuppression and bioengineering, including islet encapsulation and thrombo-regulatory modifications, further enhance graft viability. While recent breakthroughs, including pig-to-human transplants, demonstrate considerable clinical potential, challenges remain in achieving long-term graft survival. This review summarizes current progress in xenotransplantation research and outlines future directions to overcome cross-species immune barriers, bringing the field closer to widespread clinical application.

Elucidating the critical role of gut microbiota in the pathogenesis of bacterial pneumonia: insights from a Mendelian randomization analysis mediated by immune cell

BackgroundThe gut microbiota (GM) is recognized as a critical factor in sustaining overall health and regulating the immune system. However, the precise function of GM in the pathogenesis of bacterial pneumonia (BP), as well as the potential involvement of immune cells in these mechanisms, remains inadequately understood. Given that BP represents a substantial public health issue, elucidating the protective role of the gut microbiota against this condition is of considerable significance.MethodsWe employed a bidirectional two-sample univariate Mendelian randomization (UVMR) approach to investigate the potential causal relationship between GM and BP. Furthermore, we integrated UVMR with multivariate Mendelian randomization (MVMR) analysis to assess the mediating role of immune cells in the pathway linking GM to BP risk. We additionally performed a reverse analysis to exclude GM that could exhibit a reverse causal relationship with BP.ResultsMendelian randomization (MR) analysis identified 18 GM significantly associated with BP, with 8 of these bacterial taxa linked to a reduced risk and 10 associated with an increased risk. Additionally, 50 immune cell traits exhibited suggestive associations with BP, with 27 immune cells potentially conferring protection and 23 immune cells potentially augmenting risk. Importantly, mediation MR analysis revealed that the protective effect of Clostridia on BP was predominantly mediated by the proportion of HLA DR + Natural Killer cells within CD3- lymphocytes (HLA DR + Natural Killer %CD3- lymphocytes) (Total effect IVW: OR = 0.724, 95% CI [0.552, 0.950], P = 0.020). The evaluation of the mediation effect revealed an effect size of -0.025 (95% CI [-0.061, -0.000]), with a mediation effect ratio of 7.143%.ConclusionThe study identified specific components of the GM that confer a protective effect against BP. It revealed that the subsets of HLA DR + Natural Killer %CD3- lymphocytes are modulated by Clostridia, thereby enhancing the host’s immune defense against BP.

Recent advances in non-invasive in vivo tracking of cell-based cancer immunotherapies.

Immunotherapy has been at the forefront of cancer treatment research in recent years due to an increased understanding of the immune system's role in cancer and the substantial benefits it has demonstrated compared to conventional treatment methods. In particular, immune cell-based approaches utilizing T cells, natural killer (NK) cells, macrophages, and more have shown great potential as cancer treatments. While these treatments hold promise, there are still numerous issues that limit their clinical translation, including a lack of understanding of their mechanisms and inconsistent responses to treatment. Traditionally, tissue or blood samples are collected as a means of monitoring treatment progression. However, these in vitro diagnostics are invasive and provide limited information about the real-time status of the treatment or its long-term effectiveness. To address these limitations, novel non-invasive imaging modalities have been developed. These include optical imaging, X-ray computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and single-photon emission computed tomography (SPECT), and photoacoustic (PA) imaging. This review focuses on methods for tracking cell-based cancer immunotherapies using these in vivo imaging modalities, thereby enhancing real-time monitoring of their therapeutic effect and predictions of their long-term efficacy.

Galloylated Toll-Like Receptor 7/8 Agonist Nanovaccine for Enhanced Tumor Antigen Delivery in Personalized Immunotherapy.

Cancer vaccines, a critical technology in cancer immunotherapy, have shown great therapeutic potential. However, traditional vaccines based on tumor cell lysates (TCLs) have shown disappointing results in early clinical trials due to low immunogenicity, in vivo instability, and the inability to codeliver with adjuvants. To address these issues, we developed a nanoparticle vaccine, R848-GA@TCLs, by modifying the toll-like receptor 7/8 (TLR7/8) agonist R848 with gallic acid. This nanovaccine leverages the "capturing" ability of the galloyl moiety to coload TCLs and R848, forming stable nanoparticles. R848-GA@TCLs efficiently target lymph nodes, increasing TCL accumulation 10-fold, and enable the synchronized release of antigens and adjuvants within dendritic cells (DCs). Our results show that R848-GA@TCLs increase with respect to the cross-presentation of tumor antigens, promote the production of pro-inflammatory cytokines, and activate DCs, leading to a significant increase in effector T cells, natural killer (NK) cells, and M1 macrophages. This strong immune response resulted in potent antitumor effects, with R848-GA@TCLs demonstrating efficacy in multiple tumor models by significantly inhibiting tumor growth and metastasis. In conclusion, R848-GA@TCLs represent a personalized cancer vaccine capable of codelivering TCLs and adjuvants, eliciting robust antitumor immune responses, and hold great potential for clinical applications.

Exosomes derived from natural killer cells: transforming immunotherapy for aggressive breast cancer.

Natural killer cell-derived exosomes (NK-Exos) hold great promise as immune modulators and immunotherapeutics against cancer due to their intrinsically latent anti-tumor effects. They use these nanosized vesicles to deliver cytotoxic molecules, such as perforin, granzymes, and miRNAs, directly to cancer cells to kill them, avoiding immune suppression. NK-Exos has particular efficacy for treating aggressive breast cancer by modulating the TME to activate the immune response and suppress immunosuppressive factors. Bioengineering advances have extended the therapeutic potential of NK-Exos, which permits precise tumor cell targeting and efficient delivery of therapeutic payloads, including small RNAs and chemotherapeutic agents. In engineered NK-Exos, sensitization of cancer cells to apoptosis, reduction of tumor growth, and resistance to drugs have been demonstrated to be highly effective. When combined, NK-Exos synergizes with radiotherapy, chemotherapy, or checkpoint inhibitors, enhancing therapeutic efficacy, and minimizing systemic toxicity. This review emphasizes the critical role of NK-Exos in breast cancer treatment, their integration into combination therapies, and the need for further research to overcome existing limitations and fully realize their clinical potential.

Immunological landscape of children with Mycoplasma pneumoniae pneumonia in the post-COVID-19 era reveals distinctive severity indicators

BackgroundThere is a recent global surge in Mycoplasma pneumoniae pneumonia (MPP). However, the key immune factors that contribute to the advancement of the disease remain unknown. Hence, we conducted this study to uncover the immunological profile in children affected by MPP.MethodsThis study enrolled children visiting Children’s Hospital of Fudan University from December 2023 to April 2024, including 34 healthy controls, 51 severe MPP (S-MPP), 27 non-severe MPP (NS-MPP), and 34 non-MPP pneumonia (NMP) cases. Their blood samples were analyzed using flow cytometry, multi-cytokine assays, and antibody detection methods.ResultsCompared with NMP cases, MPP cases displayed higher frequencies of natural killer T cells, classical monocytes, and monocytic myeloid-derived suppressor cells. Notably, both T helper type 1 and activated regulatory T cells were more abundant in MPP cases, particularly in S-MPP, whereas CD8 + T cells displayed an exhaustion phenotype. The proportion of naïve B cells was reduced, while functional B cells, including memory B cells and plasmablasts, increased in S-MPP. 12 out of 95 clinical laboratory indicators and 3 out of 48 cytokines significantly differed between S-MPP and NS-MPP. Finally, we performed logistic and LASSO regression analyses and developed a predictive model for S-MPP that incorporates naïve B cell percentage from flow cytometry, cholinesterase from clinical laboratory tests, and interleukin 18 from the cytokine assay.ConclusionsThese results clarify the immunological features in pediatric MPP cases, and identify novel markers for severe cases, providing insights for early diagnosis and immunological management in affected children.

Vorinostat restores iNKT cell functionality in aggressive cholangiocarcinoma.

Vorinostat restores iNKT cell functionality in aggressive cholangiocarcinoma.

Exploring the genetic mechanisms driving KIR diversification.

Killer cell immunoglobulin-like receptors (KIRs) are key modulators of natural killer cell activity, displaying either activating or inhibitory potential upon recognition of major histocompatibility complex (MHC) class I molecules. The genomic organization of KIR genes is complex, involving copy number variation and allelic polymorphism, which is probably due to their coevolution with highly polymorphic MHC ligands. The KIR diversity is reflected by more than 70 similar region configurations encountered in humans, generated through meiotic recombination events. Rhesus macaques happen to display even more diversity, and over 100 distinct configurations were identified in a relatively small cohort of animals. More than half of these region configurations feature hybrid KIR genes, suggesting a more pronounced mode of diversification in macaques. The molecular mechanism facilitating meiotic rearrangements in the KIR region is poorly understood. Examination of 21 rhesus macaque and 14 human KIR region configurations revealed the presence of long terminal repeats and PRDM9 binding motifs associated with recombination hotspots. The variable DNA recognition patterns of PRDM9 could potentially contribute to the differing recombination activities documented for the KIR region in humans and macaques. The diversification process of the KIR repertoire in natural killer cells is fundamentally distinct from the mechanisms generating T and B cell receptor diversity or MHC polymorphisms. This sophisticated recombination machinery preserves the functional integrity by the frequent generation of in-frame KIR genes. A diverse KIR repertoire contributes to the protection of individuals and populations against pathogen evasion and subversion.

Cyclin E1 overexpression triggers interferon signaling and is associated with antitumor immunity in breast cancer

BackgroundCyclin E1 overexpression drives oncogenesis in several cancers through deregulation of DNA replication and induction of genomic instability, which may potentially trigger immune signaling via cytoplasmic DNA. However, the effects...

The causal effects between autoimmune thyroid disease and urticaria: evidence from a Mendelian randomization study.

Previous studies have suggested a comorbidity between autoimmune thyroid disease (AITD) and urticaria. However, the causal effects between AITD and urticaria remain unclear. This study employed genome-wide association study (GWAS) data to analyze the associations between AITD and urticaria through bidirectional Mendelian randomization (MR), meanwhile, examined the role of 731 immune traits as mediators between the two diseases through mediation analysis. The IVW results indicated that Graves' disease (GD) and Hashimoto's thyroiditis (HT) have a potential risk effect on urticaria, particularly increasing the risk of other and unspecified urticaria and idiopathic urticaria. Urticaria, mainly other and unspecified urticaria, dermatographic urticaria demonstrated a potential risk effect on HT. The mediation analysis revealed that GD likely increases the risk of other and unspecified urticaria by reducing CD4-CD8- Natural Killer T Absolute Counts, and reduces the levels of three types of T cells thereby increasing the risk of idiopathic urticaria. HT increased the risk of idiopathic urticaria through reducing the levels of two types of myeloid Dendritic Cells. The study revealed both GD and HT have causal associations with urticaria, particularly with other and unspecified urticaria and idiopathic urticaria. GD and HT may elevate the risk of spontaneous urticaria by regulating different immune traits.

Irreversible electroporation combined with anti-programmed cell death protein 1 therapy promotes tumor antigen-specific CD8+ T cell response.

Irreversible electroporation (IRE) is a novel local tumor ablation approach with the potential to activate the host's immune system. However, this approach is insufficient to prevent cancer progression, and complementary approaches are required for effective immunotherapy. To assess the immunomodulatory effects and mechanism of IRE combined anti-programmed cell death protein 1 (PD-1) treatment in subcutaneous pancreatic cancer models. C57BL-6 tumor-bearing mice were randomly divided into four groups: Control group; IRE group; anti-PD-1 group; and IRE + anti-PD-1 group. Tumor-infiltrating T, B, and natural killer cell levels and plasma concentrations of T helper type 1 cytokines (interleukin-2, interferon-γ, and tumor necrosis factor-α) were evaluated. Real-time PCR was used to determine the expression of CD8 (marker of CD8+ T cells) in tumor tissues of the mice of all groups at different points of time. The growth curves of tumors were drawn. The results demonstrated that the IRE + anti-PD-1 group exhibited significantly higher percentages of T lymphocyte infiltration, including CD4+ and CD8+ T cells compared with the control group. Additionally, the IRE + anti-PD-1 group showed increased infiltration of natural killer and B cells, elevated cytokine levels, and higher CD8 mRNA expression. Tumor volume was significantly reduced in the IRE + anti-PD-1 group, indicating a more pronounced therapeutic effect. The combination of IRE and anti-PD-1 therapy promotes CD8+ T cell immunity responses, leading to a more effective reduction in tumor volume and improved therapeutic outcomes, which provides a new direction for ablation and immunotherapy of pancreatic cancer.

Effects of Melatonin on Level of Cytokine in Patients with AIDS

Aims: Changes in cytokine levels in HIV infected individuals can affect the function of the immune system and have the potential to directly impact the course of HIV disease by enhancing or suppressing HIV replication. Melatonin influences various immune cells, including lymphocytes, macrophages, and natural killer (NK) cells. It can enhance the proliferation and activity of T cells and B cells, improve macrophage function, and increase NK cell cytotoxicity. Recent studies also explore its potential therapeutic benefits in various immune-related conditions. Current study evaluates the effect of the use of oral melatonin in levels cytokines pro and anti-inflammatory on HIV patients undergoing antiretroviral therapy. Methodology: An intervention study was carried out where the researcher chooses an exposure factor or intervention causing an intentional modification in some aspect of the health status through the introduction of a specific therapy. HIV patients were evaluated before and after melatonin administration melatonin (6mg) once a day, in the evening, for one month. Patients who used antiretroviral therapy and wished to take part in the study were eligible for the study. Each patient's cytokine profile was evaluated before starting treatment and after 30 days of treatment. Cytokine dosing by flow cytometry is a highly sensitive and specific method, allowing simultaneous analysis of multiple cytokines:interleukin 2 (IL-2), interleukin 4 (IL-4), interleukin 6 (IL-6), interferon gamma (IFN-γ) interleukin 10 (IL-10) and tumor necrosis factor (TNF- α) before and after melatonin supplementation for 30 days in 28 patients. Results: The results obtained demonstrate that there were changes before and after the use of melatonin in the levels of the cytokines interleukin 4 (IL-4), interleukin 6 (IL-6), interferon gamma (IFN-γ), interleukin 10 (IL-10) and tumor necrosis factor (TNF- α) but not for interleukin 2 (IL-2), The cytokines tumor necrosis factor (TNF-α) had increased levels and interleukin 4 (IL-4), interleukin 6 (IL-6), interferon gamma (IFN-γ) and interleukin 10 (IL-10) levels were lower than initial levels. In this study, around 50% of patients had a reduction in IL-10 levels after using melatonin 6mg/day/30 days suggest sting that the use of melatonin could be modulating the immune response. There are studies that indicate a reduction in IL-10 levels in patients using HAART therapy. Our study not only corroborates this information but suggests that the use of melatonin supplementation enhances these effects. The cytokines tumor necrosis factor (TNF-α) had increased levels and interleukin 4 (IL-4), interleukin 6 (IL-6), interferon gamma (IFN-γ) and interleukin 10 (IL-10) levels were lower than initial levels. Conclusion: The study suggested that supplementation with melatonin at a dose of 6 mg/day could modulate the immune response through changes in the production of pro- and anti-inflammatory cytokines in patients using HAART therapy. In addition to cytokines, melatonin in AIDS interacts with factors like oxidative stress, immune system modulations and viral replications.

Transmembrane protein 176B promotes epithelial-mesenchymal transition in colorectal cancer through inflammasome inhibition.

Activation of the epithelial-mesenchymal transition (EMT), a pivotal process in tumor metastasis and evasion, as well as the NLRP3 inflammasome, both promote colorectal cancer (CRC) progression. Recent studies have shown that Transmembrane protein 176B (TMEM176B) regulates NLRP3 and promotes CRC malignant phenotypes. To investigate the role of TMEM176B in modulating NLRP3 inflammasome and its implications on EMT and tumor progression in CRC. CRC in situ mouse and co-cultured cell models were established using CT26 cells, BALB/c mice, and primary cultured mouse natural killer (NK) cells. Short hairpin RNA knocked down TMEM176B and NLRP3 expression in CT26 cells. Fluorescence imaging, Terminal deoxynucleotidyl transferase dUTP nick end labeling assays, immunohistochemistry staining, flow cytometry, and molecular assays were used to investigate the effects of TMEM176B knockdown on the NLRP3 inflammasome in NK cells to assess tumor metastasis, apoptosis, and EMT indicators. Silencing TMEM176B in CRC mice significantly reduced tumor metastasis, proliferation, and EMT, while activating apoptosis, NLRP3 inflammasome, and NK cell activity. Furthermore, silencing TMEM176B in co-cultured cell models inhibited cell migration and invasion, and promoted apoptosis. The interference of NLRP3 reversed these effects by modulating key proteins such as phosphorylated nuclear factor kappa B subunit 1 p65, matrix metallopeptidase 9, and transforming growth factor-β. This study highlights the critical role of TMEM176B/NLRP3 in CRC progression and provides a basis for targeting this axis as a novel therapeutic approach to manage CRC progression and metastasis.

Effect of delayed isolation of peripheral blood mononuclear cells on cell viability and functionality

BackgroundPeripheral blood mononuclear cells (PBMCs) are valuable biomarkers, providing crucial insights into the patients’ immune system. Reliable biobanking of PBMCs is essential to minimize heterogeneity. In multicenter trials, blood sample transportation to central laboratories can increase the time between blood collection and PBMC isolation. This study evaluated the effect of prolonged blood hold time on PBMC viability and cytotoxicity.MethodsFrom July 2021 to May 2023, 104 patients with early HER2-positive breast cancer were enrolled in the NeoOn trial, of whom 49 patients were included in this subproject. PBMCs were isolated ≤ 6 hours (h) or ≥ 20 h after blood collection. PBMC yield and viability were determined using the LUNA-II Automated Cell Counter. Flow cytometry was used to quantify in vitro cytotoxicity, the percentage of natural killer (NK) and T cells, as well as apoptotic and necrotic cells.ResultsIsolating PBMCs ≥ 20 h resulted in a higher cell yield, but lower NK cell viability compared to PBMCs ≤ 6 h. PBMCs ≥ 20 h were less robust to thawing and showed higher loss during recovery. Compared to PMBCS ≤ 6 h, PBMCs ≥ 20 h exhibited lower antibody-mediated cytotoxicity (p ≤ 0.0001) and antibody-dependent phagocytosis (p < 0.0051). While the percentage of T and NK cells and the T cell viability remained unaffected by hold time, the percentage of apoptotic NK cells was higher for PBMCs ≥ 20 h (41.0 ± 12.9% vs. 23.8 ± 13.4%; p = 0.0364).ConclusionsExtended blood storage time caused increased apoptosis and necrosis of NK cells, adversely affecting PBMC quality and reducing NK cell related functionality. Hence, blood hold time should be minimized to maintain PBMC integrity and NK cell functionality for in vitro biomarker assays.Trial registrationTrial registration number: EudraCT 2020-001943-21. Date of registration: December 29th 2020

Neuroimmunoendocrine dysfunctions in case of bacterial purulent meningitis in children

Objective: to study neuroimmunoendocrine dysfunctions in children with bacterial purulent meningitis and to determine their value in the character of the disease course and outcomes.Materials and methods. 56 children hospitalized to Pediatric Research and Clinical Center for Infectious Diseases with the diagnosis of bacterial purulent meningitis were examined. Besides standard clinical, biochemical and hemostasis tests there were studied concentration of cytokines by xMAP technology; A, M, and G immunoglobulins – by quantitative immunoturbodimetric method; cortisol, neurospecific proteins – by immune-enzyme test; blood subpopulations of lymphocytes – by flow cytofluorimetry method.Results. Different changes of laboratory indicators characterizing neuroimmunoendocrine dysfunctions dependent on severity of the course and outcome of bacterial purulent meningitis were identified. Children with more severe course of the disease during its acute period had a reliable increase of S-100 protein in blood serum, concentration of granulocytic colony-stimulating, and concentration of BВ subunit produced by growth factor platelets was decreased. In case of the formation of expressed neurologic consequences within the disease outcome, higher concentration of neurospecific enolase, relative content of natural killers, and lower concentration of monocytic chemoattractant protein 1 were identified during the period of reconvalescence in comparison with a favorable neurologic outcome.Conclusion. The results of the study give evidence of the possibility of more accurate early prognosis of the disease course and outcome on the basis of evaluation of neuroimmunoendocrine dysfunctions and this is extremely important to determine therapy management during both acute and reconvalescence periods of bacterial purulent meningitis.

Angiopoietin-2 regulates the phenotypic switch of vascular smooth muscle cells.

During uterine spiral artery remodeling, vascular smooth muscle cells (VSMCs) become disorganized and undergo phenotypic switching from a contractile to a more synthetic phenotype. We have previously reported that uterine natural killer cells induce this VSMC phenotypic switching by secreting angiopoietin-2 (Ang-2). Here, we identified the specific mechanisms by which Ang-2 plays a role in this phenomenon. VSMCs isolated from human umbilical arteries were used as an invitro model to investigate the role of Ang-2 in phenotypic switching. Human decidua tissue from preeclamptic and control pregnancies was collected to compare the expression levels of related proteins. Ang-2 induced a more synthetic phenotype in VSMCs as evidenced by decreased contractile marker expression, increased proliferation and migration, and an altered cytoskeleton. VSMC expressed integrin β6 interacted directly with Ang-2 and induced phosphorylation of FAK (S910 and Y397), AKT (S473), and mTOR (S2448). Knockdown of FAK recovered the calponin loss induced by Ang-2 and resulted in lower EZH2 abundance. Inhibition of FAK and EZH2 both attenuated Ang-2-induced inhibition of the LC3 II/LC3 I ratio and ATG7 expression, and proliferation. Lipid peroxidation inhibition by ferrostatin-1 or the IL-8 receptor antagonist navarixin inhibited the Ang-2-induced migration. IL-8 secretion was significantly lower with lipid peroxidation inhibition. In preeclamptic decidua, there were more unremodeled spiral arteries, and the abundance of Ang-2 was dysregulated. Ang-2 dysregulation may disrupt spiral artery remodeling and contribute to preeclampsia. Ang-2 may be a novel therapeutic target for the treatment of pregnancy complications affected by incomplete spiral artery remodeling.

HLA-E/peptide complexes differentially interact with NKG2A/CD94 and T cell receptors.

The virtually monomorphic antigen presentation molecule HLA-E can present self- and non-self peptides to the NKG2A/CD94 co-receptor inhibitory complex expressed on natural killer (NK) cells and to T cell receptors (TCRs) expressed on T cells. HLA-E presents self-peptides to NKG2A/CD94 to regulate tissue homeostasis, whereas HLA-E restricted T cells mediate regulatory and cytotoxic responses toward pathogen-infected cells. In this study, we directly compared HLA-E/peptide recognition and signaling between NKG2A/CD94 and 2 HLA-E restricted TCRs that can recognize self-peptides or identical peptide mimics from the viral UL40 protein of cytomegalovirus using position substituted peptide variants. We show that position 7 is critical for interaction with NKG2A/CD94, whereas position 8 is important for interaction with the TCRs. The Arginine at position 5 of these peptides is an essential residue for recognition by both receptors. Thus, NKG2A/CD94 and TCRs have different requirements for recognition of peptides presented in HLA-E.

Long-Term Evaluation of Effectiveness and Immunological Implications of Ocrelizumab in a Real-World Cohort.

Extended follow-up data from real-world cohorts of patients with multiple sclerosis treated with ocrelizumab (OCR) are becoming widely available. This monocentric retrospective study aimed to evaluate the long-term effectiveness of OCR and its impact on immunoglobulin (Ig) levels, lymphocyte subsets, and infections in a cohort of patients with relapsing remitting, primary progressive, and secondary progressive multiple sclerosis. Patients followed at the Multiple Sclerosis Center of Bari with ≥2 years of OCR treatment were retrospectively recruited in 2024. Twelve-month confirmed disability worsening, improvement, and the annualized relapse rate before and after treatment start were estimated and follow-up magnetic resonance imaging scans were collected. Changes in IgG/IgM/IgA levels from baseline for up to 6 years of OCR treatment and serum levels of T CD4+, T CD8+, and natural killer lymphocytes were assessed. Infection occurrence, type, and outcomes were investigated. Multivariable Cox models examined the association of clinical and radiological baseline factors with the risk of confirmed disability worsening and the relationship of infections with clinical-laboratoristic risk factors. The final cohort retrieved 140 patients (80 relapsing remitting, 37 primary progressive, 23 secondary progressive) with a median (interquartile range) follow-up after treatment start of 4.62 (4.10-5.04) years. In the entire cohort, the mean annualized relapse rate decreased from 0.61 in the year before the start of OCR treatment to 0.02 in the second year, thereafter all patients in our cohort remained free of relapses and magnetic resonance imaging activity. The overall percentage of stable patients increased from the second to the fourth year, in parallel with a reduction in patients with confirmed disability worsening. A multifocal onset and the presence of at least two relapses before the start of OCR treatment were significant (p < 0.05) risk factors of confirmed disability worsening. During the follow-up, a reduction in the IgG serum level was observed, which further decreased, becoming stable after the third year. Immunoglobulin M levels slightly decreased over time, whereas IgA levels remained stable. No changes for T CD4+, natural killer cell absolute number, and a slight reduction in T CD8+ lymphocytes during follow-up were observed. Ocrelizumab did not determine a significant infection risk in the long term and no association was observed with Ig levels and severe infections. Ocrelizumab prevented disease activity over the long term and its effect on the immune system did not determine a significant infection risk in most patients.

Expression of a single inhibitory member of the Ly49 receptor family is sufficient to license NK cells for effector functions.

Natural killer (NK) cells recognize target cells through germline-encoded activation and inhibitory receptors enabling effective immunity against viruses and cancer. The Ly49 receptor family in the mouse and killer immunoglobin-like receptor family in humans play a central role in NK cell immunity through recognition of major histocompatibility complex class I (MHC-I) and related molecules. Functionally, these receptor families are involved in the licensing and rejection of MHC-I-deficient cells through missing-self. The Ly49 family is highly polymorphic, making it challenging to detail the contributions of individual Ly49 receptors to NK cell function. Herein, we showed mice lacking expression of all Ly49s were unable to reject missing-self target cells in vivo, were defective in NK cell licensing, and displayed lower KLRG1 on the surface of NK cells. Expression of Ly49A alone on an H-2Dd background restored missing-self target cell rejection, NK cell licensing, and NK cell KLRG1 expression. Thus, a single inhibitory Ly49 receptor is sufficient to license NK cells and mediate missing-self in vivo.