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PubMed2026

TMEM176B is co-expressed with TMEM176A and upregulated in peripheral blood monocytes of patients with primary Sjögren's syndrome.

OBJECTIVES: This study aims to determine the role of acid‑sensitive nonspecific cation channels transmembrane protein 176A (TMEM176A) and TMEM176B in autoimmune diseases, with a focus on primary Sjögren's Syndrome (pSS). METHODS: We examined the expression patterns of TMEM176A and TMEM176B across tissues and cells utilizing bulk RNA-seq and scRNA-seq datasets. Immunophenotyping analysis was performed by flow cytometry to compare CD62L expression between TMEM176B⁺ and TMEM176B⁻ monocytes. The proportion of TMEM176B+ cells in monocytes was interrogated in both pSS patients and healthy controls. Clinical correlations of TMEM176B with anti‑SSB antibody and complement C4 levels were also evaluated. RESULTS: TMEM176A and TMEM176B showed conserved co‑expression and were significantly upregulated in autoimmune diseases. TMEM176B⁺ monocytes displayed higher CD62L positivity rate than TMEM176B- monocytes. In pSS patients, the proportion of TMEM176B⁺ monocytes was elevated in total monocytes, classical monocytes (cMo) and intermediate monocytes (iMo). The proportion of TMEM176B+ monocytes positively correlated with anti‑SSB levels, while several TMEM176B-associated monocyte subset markers inversely correlated with C4. CONCLUSION: TMEM176A and TMEM176B are highly correlated. TMEM176B expression in monocytes is linked to pSS and may serve as a novel auxiliary diagnostic biomarker.

Humans↗

PubMed2026

Novel genetic variants identification and immune profiling in ataxia telangiectasia patients.

BACKGROUND: Ataxia telangiectasia (AT) is an autosomal recessive neurodegenerative disease. While heterozygous relatives of AT patients are known to be clinically healthy, a predisposition to various pathologies has been reported. Our aim was firstly, to further characterize the clinical features and broaden the spectrum of genetic pathogenic variants in AT patients. Secondly, we aimed to study the immune profiles of AT patients and their relatives to identify similarities or common biomarkers. METHODS: A Target Gene Sequencing for six patients suspected with AT was performed. Computational analysis was conducted to assess the pathogenicity of novel variants. The distribution of immune cells was assessed by flow cytometry in patients with AT, AT-like disorder, Friedreich ataxia, and in AT relatives. The expression pattern of candidate genes was evaluated by RT-qPCR. RESULTS: We identified and predicted the pathogenicity of novel variants in the ATM gene. Computational analysis suggested that the novel identified missense mutation could affect ATP binding pattern and ATM protein flexibility, while Alu element insertion could probably induces a premature stop codon. Furthermore, our results confirm the pathogenic effect of identified splicing mutations on the ATM transcript. Moreover, we noticed a high percentage of LTCD4 + and LTCD8 + senescent subsets in AT patients and a relative increase of the of intermediate and non-classical monocytes accompanied with a decrease of classical monocytes specifically in AT patients with truncated biallelic mutations which was intriguingly similar to the immune profile of AT parents. In addition, a difference of immune pattern was observed between AT patients with biallelic truncated mutations compared to those with at least one non-truncated mutation, with a variability intragroup. Gene expression analysis identified FOXO3, IL33 and METTL3 as putative genes that may yield clues into AT pathogenesis. CONCLUSION: Taken together, our study expands the mutational spectrum of AT disease worldwide and further characterize the immune profile of AT patients uncovering a possible difference in some immune cellular subsets related to ATM mutation type and delineate putative immune abnormalities related to ATM heterozygosity among AT parents. Furthermore, dysregulation in FOXO3, IL33 and METTL3 expression could be related to disease severity.

Humans↗

PubMed2026

Single-cell expression quantitative trait locus Mendelian randomization reveals immune cell-specific causal regulatory networks and actionable targets in polycystic ovary syndrome.

ObjectiveTo systematically investigate whether the pathogenesis of polycystic ovary syndrome (PCOS) is causally related to dysregulated gene expression in specific immune cell subsets, and to evaluate the potential of these causal genes as actionable drug targets.MethodsThis study employed a two-sample Mendelian randomization (MR) framework using publicly available genome-wide association study (GWAS) summary statistics. The participant data included 797 PCOS cases and 140,558 controls (no direct patient recruitment was involved). Instrumental variables were derived from high-resolution immune cell-specific single-cell expression quantitative trait locus (sc-eQTL) data (OneK1K project) across 14 immune cell types. Primary analyses utilized the inverse-variance weighted (IVW) method. Shared causal variants were validated using Bayesian colocalization. Phenome-wide association analysis (PheWAS), external transcriptomic dataset validation (GSE8157), and DrugBank database screening were conducted for pleiotropy assessment and drug repositioning.ResultsMR analysis revealed genome-wide significant causal associations for GLIPR1 in non-classical monocytes (Mono NC) and XBP1 in CD4+ effector memory T cells (CD4 ET) with PCOS risk. Higher GLIPR1 expression was associated with a decreased PCOS risk (OR = 0.669, P = 4.34×10-6), whereas higher XBP1 expression was associated with an increased risk (OR = 1.406, P = 9.53×10-8). Colocalization analysis confirmed that GLIPR1 shares a causal variant with PCOS (PP.H4 = 96.73%). PheWAS and external validation confirmed the safety profile and significant upregulation (P = 0.03) of GLIPR1. Drug repositioning identified SOT-107, a Phase III protein therapy drug, as a potential interacting agent for GLIPR1.ConclusionsThis sc-eQTL MR study reveals immune cell-specific causal regulatory networks in PCOS. GLIPR1 in non-classical monocytes represents a high-confidence protective target, while XBP1 provides suggestive evidence for immune-mediated pathogenesis. The candidate drug SOT-107 highlights theoretical repositioning opportunities, though rigorous preclinical validation remains required.

Female↗

PubMed2026

Integrated Cytokine and Immune Cell Profiling Reveals a Distinct Immune Signature Associated with High-Altitude Pulmonary Edema.

High-altitude pulmonary edema (HAPE) is a rapidly progressive, life-threatening disorder arising in otherwise healthy individuals upon ascent to high altitude, yet the mechanisms underlying maladaptive vascular leak remain poorly defined. Although elevated pulmonary arterial pressure and capillary stress failure are recognized as central hemodynamic drivers, accumulating evidence indicates that innate immune dysregulation is an equally critical, largely unexplored determinant of HAPE. To systematically delineate the immune and molecular programs that distinguish pathological responses to hypobaric hypoxia from acclimatization, peripheral blood along with clinical details was collected from low-altitude controls (LA-Cntrl, number of participants, (n = 19), healthy high-altitude sojourners (HA-Cntrl, n = 47), and HAPE patients (n = 90). Plasma proteomic markers were quantified using a targeted panel, while monocyte and dendritic cell subsets in peripheral blood mononuclear cells were immunophenotyped by multicolor flow cytometry. HA-Cntrl subjects displayed an anti-inflammatory profile, marked by the suppression of CXC chemokine receptor 3 axis chemokines. HAPE patients, in contrast, exhibited a pro-inflammatory, vascular injury signature, with elevated levels of inflammatory interleukins and myeloid and chemotactic factors. This inflammatory signature was accompanied by the expansion of classical monocytes, implicating a myeloid vascular program associated with HAPE.

Humans↗

PubMed2015

Patrolling monocytes control tumor metastasis to the lung.

The immune system plays an important role in regulating tumor growth and metastasis. Classical monocytes promote tumorigenesis and cancer metastasis, but how nonclassical "patrolling" monocytes (PMo) interact with tumors is unknown. Here we show that PMo are enriched in the microvasculature of the lung and reduce tumor metastasis to lung in multiple mouse metastatic tumor models. Nr4a1-deficient mice, which specifically lack PMo, showed increased lung metastasis in vivo. Transfer of Nr4a1-proficient PMo into Nr4a1-deficient mice prevented tumor invasion in the lung. PMo established early interactions with metastasizing tumor cells, scavenged tumor material from the lung vasculature, and promoted natural killer cell recruitment and activation. Thus, PMo contribute to cancer immunosurveillance and may be targets for cancer immunotherapy.

Animals↗

PubMed1979

[Nucleophagocytosis in monocytes--an immunocytologic phenomenon of anti-dna-antibodies].

In SLE-sera antinuclear antibodies pervent normal nuclear degeneration, i.e. lysis of free nuclei. In sera with high titers, small rigid LE-bodies develop rapidly, which are soon phagocytized in toto by neutrophil granulocytes and monocytes. Classic LE-cells as well as Tart-cells are formed. The foreign appearance of the phagosomes in the monocytes is a result of the different digestive processes occuring in these phagocytes. With decreasing serum activity, the LE-bodies expand somewhat more and become viscous. From these nuclei, relatively small portions are phagocytized fairly late. Sjögren-cells of the granulocytic as well as the monocytic type are generated. Nucleophagocytosis only occurs in the presence of antinuclear antibodies, regardless of whether it leads to LE-cell, Tart-cell or partial phagocytosis, i.e. Sjögren-cells of the granulocytic or monocytic type. A non-specific nucleophagocytosis does not exist.

Antibodies, Anti-Idiotypic↗

PubMed2025

Surgery/anesthesia may cause monocytes to promote tumor development.

BACKGROUND: The immune system of patients undergoing major surgery usually has obvious immune responses during the perioperative period, and the patient's immune status would affect the patient's prognosis. In this study single-cell sequencing technology was used to investigate the effect of surgery/anesthesia on peripheral blood mononuclear cells (PBMCs) in depth during the perioperative period. METHODS: We performed an in-depth analysis of our previously published data, which included a total of 4 patients were recruited in this study. Their peripheral blood samples were collected pre operation, 0, 24, and 48 h post operation, and then PBMCs were extracted, followed by single cell sequencing. The results of sequencing were analyzed with R packages seurat and scSTAR. Finally, RT-PCR technology was used to verify the expression of key genes in monocyte. RESULTS: The ratio of CD4+ and CD8+ T cells and Tregs showed little change, and the function of CD4+ and CD8+ T cells recovered soon. The function of Treg had not been restored 48 h post operation. Non-classical monocyte was impressed after surgery and showed no recovery trend within 48 h. Similar to scRNA-seq, the expression levels of MDM2 and SESN1 in patients with tumor increased significantly after surgery. CONCLUSIONS: Surgery/anesthesia had little effect on CD4+ and CD8+ T cells, and continued to affect the functional changes of Treg. It had more impact on monocytes, which may cause them to promote tumor development to a certain extent.

Humans↗

PubMed2026

Parallel single-cell host immune profiling and pathogen genomic characterization in Klebsiella-associated sepsis: a pilot study.

OBJECTIVES: Sepsis is a life-threatening syndrome characterized by profound immune dysregulation and substantial biological heterogeneity. Here, we conducted a pilot study to explore host immune remodeling in Klebsiella-associated sepsis by combining single-cell RNA sequencing of peripheral blood mononuclear cells with whole-genome sequencing of the corresponding bloodstream isolates. METHODS: In this prospective observational pilot study, we analyzed peripheral blood mononuclear cells (PBMCs) from two patients with Klebsiella-associated sepsis and two healthy controls (HC) using single-cell RNA sequencing. PBMC composition, differential transcriptional responses, and pathway analysis were assessed across immune subsets. The corresponding bloodstream isolates were characterized by phenotypic antimicrobial susceptibility testing and whole-genome sequencing. RESULTS: Compared to HC, septic patients showed expansion of the myeloid compartment and contraction of the NK/T compartment. High-resolution analysis suggested shifts within lymphoid populations. At the transcriptional level, sepsis was associated with compartment-specific enrichment of interferon-related and host-defence pathways, as well as oxidative phosphorylation, ATP synthesis, and mitochondrial electron transport signatures across multiple PBMC subsets. Classical monocytes exhibited a coordinated decrease in MHC class II-related transcripts. The sepsis-associated isolates were identified as Klebsiella pneumoniae and Klebsiella variicola and were notable for overall antimicrobial susceptibility, limited resistomes, and absence of canonical hypervirulence determinants. CONCLUSION: Our data provide a preliminary description of immune remodeling during Klebsiella-associated sepsis and suggest that severe clinical disease may be associated with isolates lacking classical multidrug-resistance or hypervirulence features. These findings should be interpreted as preliminary and hypothesis-generating and require validation in larger cohorts with detailed clinical severity assessment.

Female↗

PubMed2025

Paradoxical Effect of Myosteatosis on the Immune Checkpoint Inhibitor Response in Metastatic Renal Cell Carcinoma.

BACKGROUND: Treatment for metastatic renal cell carcinoma (mRCC) has shifted from tyrosine kinase inhibitor (TKI) therapy to immune checkpoint inhibitor (ICI)-based therapy, improving outcomes but with variable individual responses. This study investigated the prognostic implications of pretreatment low skeletal muscle mass (LSMM) and myosteatosis in patients with mRCC undergoing first-line ICI-based therapies, comparing outcomes between PD-1 inhibitor + CTLA-4 inhibitor and PD-1 inhibitor + TKI, incorporating single-cell RNA sequencing. METHODS: A retrospective analysis was performed on 90 patients with mRCC treated with ICI-based therapies between November 2019 and March 2023. Patients were grouped based on whether they received PD-1 inhibitor + CTLA-4 inhibitor or PD-1 inhibitor + TKI combinations. LSMM was defined as skeletal muscle index below 40.8 cm2/m2 for men and 34.9 cm2/m2 for women. Myosteatosis was defined using skeletal muscle density, with cut-off values < 41 HU for BMI < 25 kg/m2 and < 33 HU for BMI ≥ 25 kg/m2. Progression-free survival (PFS) and overall survival (OS) were compared using Kaplan-Meier curves and multivariable models. Single-cell RNA sequencing was performed on pretreatment samples to compare the immune microenvironment between patients with and without myosteatosis. RESULTS: The study cohort (26.7% female; median age: 60.5 years) included 59 patients (65.6%) treated with PD-1 inhibitor + CTLA-4 inhibitor and 31 patients (34.4%) treated with PD-1 inhibitor + TKI. LSMM was present in 18.9% of patients, and myosteatosis in 41.1%, with comparable proportions across groups. During follow-up, 29 patients (32.2%) died: 16 in the PD-1 inhibitor + CTLA-4 inhibitor group and 13 in the PD-1 inhibitor + TKI group. The overall 1-year mortality rate was 22.2%, and PFS rate was 53.3%. Myosteatosis predicted poor OS (HR, 5.389; p = 0.008) and PFS (HR, 2.930; p = 0.022) in the PD-1 inhibitor + TKI group but was protective for PFS (HR, 0.461; p = 0.049) in the PD-1 inhibitor + CTLA-4 inhibitor group. LSMM did not significantly affect outcomes in either group. Single-cell RNA sequencing revealed higher CTLA-4 expression in regulatory T cells and more effector memory CD8+ T cells in patients with myosteatosis, whereas patients without myosteatosis had more anti-tumoural non-classical monocytes. CONCLUSIONS: Myosteatosis negatively impacts OS and PFS in patients with mRCC treated with PD-1 inhibitor + TKI therapy but is protective for PFS in those treated with PD-1 inhibitor + CTLA-4 inhibitor therapy. Altered checkpoint expression and immune cell composition associated with myosteatosis may contribute to these differential responses.

Humans↗

PubMed2026

Multiparametric flow cytometry immune profiling of pulmonary and extra-pulmonary tuberculosis reveals distinct blood-based biomarker signatures.

This study investigated immune cell distributions, cell-specific immune markers, and selected biomarker targets in pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB) using multiparametric flow cytometry (MFC). Whole blood was collected from 45 individuals, including healthy controls (HC), EPTB, and PTB patients (n = 15/group). Peripheral blood leukocytes were analysed by MFC to characterize CD4+ and CD8+ T cells, natural killer (NK), invariant NKT (iNKT) and NKT cells, classical (CM), intermediate (IM) and non-classical monocytes (NCM), and activated monocytes (AM). Expression of GBP1, CALCOCO2, IFIT3, SNX10, ARG1, PD-1, and PD-L1 was assessed across these immune subsets. Increased frequencies of NK, NKT, and monocytes were observed in PTB and EPTB compared with HC, while CD4+, CD8+, iNKT, and AM were reduced. Monocyte-to-lymphocyte ratios were incrementally elevated in EPTB and PTB compared with HC. Despite variability of expression within groups, median biomarker fold-change expression changes were found between HC, EPTB and PTB groups; (i) (>2.0FC) for ARG1 in CD4, CD8, CM and AM, for CALCOCO2 in AM, GBP1 in CD8 and NCM, PD-1 in CD4, CD8, NK, IM and AM, PD-L1 in CD4, CD8, iNKT and NKT, NK, IM and AM and SNX10 in CD4, CD8, NCM, IM and AM (ii) (<2.0FC) in TB vs HC for CALCOCO2 in iNKT and NKT, IFIT3 in NCM, PD-1 in NK and NCM, PD-L1 in NCM, IM and AM and SNX10 in AM. Statistical significance was achieved for ARG1 (P = 0.017) in CD4 cells. Our findings highlight distinct immune cell and biomarker signatures in PTB and EPTB.

Humans↗

PubMed2026

Th2 bias and T-cell exhaustion characterize the immunopathology of non-tuberculous mycobacterial pulmonary disease.

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is an escalating global health concern with poorly defined immunological mechanisms, necessitating comprehensive profiling to guide therapeutic advances. We analyzed peripheral blood from 28 treatment-naïve NTM-PD patients (19 Mycobacterium avium complex, 9 Mycobacterium abscessus) and 27 matched controls using 42-marker mass cytometry (CyTOF) and Luminex multiplex assays. A random forest model identified predictive markers, while an in vitro murine macrophage model evaluated chemokine production. NTM-PD patients displayed significant immune shifts, including increased classical monocytes (CD14+ CD16-), reduced NKT-like cells (CD3+ CD56+), and elevated T-cell exhaustion markers (PD-1, TOX). This coincided with a Th1/Th2 balance shift characterized by heightened IL-13. Elevated IFN-γ-inducible chemokines CXCL9 and CXCL10 coexisted with this Th2-biased signature, indicating a complex, dysregulated inflammatory state. A model integrating immune-cell frequencies and cytokine profiles achieved robust diagnostic accuracy (AUC = 0.922) with prognostic potential. In vitro, NTM-infected macrophages produced substantial CXCL9 and CXCL10 levels relative to the LPS maximal activation benchmark, identifying them as a major cellular source. These findings propose an immunological framework wherein T-cell exhaustion and a Th2-biased microenvironment strongly correlate with NTM-PD pathogenesis. CXCL9, CXCL10, and IL-13 emerge as candidate therapeutic targets, while our predictive model offers a foundational approach for risk stratification.

Humans↗

PubMed2026

Human airspace macrophage signatures are conserved during sterile lung injury and repair.

RATIONALE: Airspace macrophages (AM) are implicated in both persistent inflammation and tissue repair following acute lung injury. Distinct subsets of AM are associated with lung pathology in humans but whether unique AM signatures are specific to disease states or represent a conserved response to lung inflammation is unknown. OBJECTIVES: We sought to test the hypothesis that conserved subsets of inflammatory and reparative AM could be identified by transcriptional programing in a human model of self-resolving acute lung injury. METHODS: Fifteen subjects underwent bronchoscopic lavage (BAL) before and at a pre-assigned time point after endobronchial exposure to bacterial endotoxin. BAL cells were subjected to single cell RNA sequencing and longitudinal assessment of AM programing during resolution of inflammation and lung repair was performed. MEASUREMENTS AND MAIN RESULTS: We identify transcriptionally distinct subsets of tissue resident and recruited AM present at all time points, in all subjects. Two recruited AM populations increase following inflammation, one which aligns with classical monocytes (MoAM) and one with interstitial macrophages (IAM). AM subsets display unique patterns of gene expression throughout the time course. Comparison of subset-specific markers to those identified in disease states reveals that IAM express many so-called "pathogenic" markers during normal lung repair. CONCLUSIONS: By applying a uniform inflammatory stimulus to healthy adults and examining BAL cells obtained at precise time points thereafter, we construct a time-resolved kinetic of AM transcriptional programing during typical lung repair. Our data demonstrate that IAM share transcriptional similarity to AM identified in disease states and suggest they may reflect a conserved cellular response to tissue injury.

Journal Article↗

PubMed2026

Cell Type-Resolved Causal Inference and Spatial Transcriptomic Integration Reveal Immune-Specific Genetic Drivers of Autoimmune and Malignant Thyroid Disease.

BACKGROUND: Thyroid diseases, including autoimmune thyroid disease (AITD) and thyroid cancer, are characterized by immune dysregulation, yet the cell type-specific genetic mechanisms underlying these conditions remain poorly understood. Most genome-wide association studies (GWAS) have relied on bulk tissue expression quantitative trait loci (eQTL), which cannot resolve the heterogeneity of immune cell populations. METHODS: We performed two-sample Mendelian randomization (MR) analyses using single-cell cis-eQTLs from 14 immune cell subtypes (OneK1K cohort) as instrumental variables against GWAS summary statistics for four thyroid outcomes: autoimmune hyperthyroidism, autoimmune hypothyroidism, thyroid cancer and autoimmune thyroiditis. Causal associations were validated through Bayesian colocalization, phenome-wide association analysis (PheWAS) and multi-layered transcriptomic validation encompassing spatial transcriptomics of AITD tissue (GSE248205), bulk RNA-seq of thyroid cancer (GSE3678) and single-cell RNA-seq of thyroid tumours (GSE250521). gsMap spatial LD score regression was applied to map disease heritability onto spatial tissue architecture. RESULTS: We identified six Bonferroni-significant causal gene-cell type pairs for autoimmune hyperthyroidism, including protective effects of ABHD16A in naïve/immature B cells (OR = 0.440), HIST1H3H in CD8 NC T cells (OR = 0.324), HMGN4 in NK recruiting cells (OR = 0.556) and ZKSCAN4 in CD8 S100B T cells (OR = 0.427), with five pairs showing strong colocalization (PP.H4 ≥ 86%). Three pairs reached significance for autoimmune hypothyroidism, including a risk association of HLA-F in CD4 NC T cells (OR = 1.139). For autoimmune thyroiditis, FAM134B/RETREG1 showed consistent suggestive protective associations across both CD4 and CD8 NC T cells (PP.H4 ≥ 90% for both), suggesting a possible involvement of ER phagy regulation in thyroiditis susceptibility. Thyroid cancer showed a suggestive association with HLA-G in classical monocytes (OR = 1.899, PP.H4 = 53%). Spatial transcriptomic validation demonstrated progressive immune infiltration from control tissue to Graves' disease to Hashimoto's thyroiditis (7.7%-15.7%, 46.1%-54.1%, respectively) and strong spatial correlation between target gene expression and corresponding cell type enrichment (e.g., plasma cell-HLA-DQB1: r = 0.491, p < 10-300). HLA-G was independently validated in thyroid cancer bulk (log2fc = 0.542, p = 9.51 × 10-3, AUC = 0.857) and single-cell datasets. PheWAS revealed no significant associations detected for the core candidates. gsMap identified significant enrichment of autoimmune hypothyroidism heritability in gastrointestinal tract, adrenal gland and adipose tissue (all Bonferroni p < 0.002). CONCLUSIONS: This study establishes a multi-scale analytical framework integrating cell type-resolved genetic inference with spatial tissue validation, revealing distinct immunogenetic architectures underlying autoimmune versus malignant thyroid disease. Protective genetic programs in autoimmune hyperthyroidism converge on chromatin remodelling (HIST1H3H, HMGN4, ZKSCAN4) and lipid metabolism (ABHD16A) across lymphocyte subsets, whereas thyroid cancer risk involves immune escape mediated by HLA-G in myeloid cells. The ER-phagy receptor RETREG1 represents a candidate pathway warranting further investigation in autoimmune thyroiditis. These findings provide genetically supported, cell type-specific therapeutic targets and demonstrate a generalizable strategy for dissecting the immune-mediated mechanisms of complex thyroid diseases.

Mendelian randomization↗

PubMed1977

The mononuclear cell in human blood which mediates antibody-dependent cellular cytotoxicity to virus-infected target cells. I. Identification of the population of effector cells.

Mononuclear cells (MC) from human blood were fractionated by a variety of physical and immunologic techniques, and the cellular subpopulations generated were assessed for their capacity to lyse herpes simplex virus (HSV)-infected target cells in the presence of IgG antibody to HSV. Latex phagocytosis and surface marker studies were performed in parallel in order to identify the major effector cells by their phagocytic properties and their possession of surface immunoglobulin and receptors for either sheep erythrocytes, C3, or the Fc fragment of IgG. Cytotoxic effector cell activity was unaffected or slightly enhanced after the removal of plastic-adherent or carbonyl iron-adherent MC, indicating that the major effector cell is not a classical monocyte. Similar results were obtained after removal of more than 90% of the T cells by depletion of rosette-forming cells. Likewise, effector cell activity was generally unchanged when more than 95% of the B cells were removed by filtering MC on nylon wool columns. Effector cell function was also found to be normal in three patients with B cell-deficient X-linked agammaglobulinemia. These observations strongly suggest that the effector cells are not T cells or B cells. A 4- to 5-fold enrichment in effector cells, however, was consistently found in a subpopulation, consisting of 5% of the unfractionated MC, that was dramatically enriched both for nonphagocytic cells with only Fc receptor (K cells) and for nonphagocytic cells with no detectable surface markers (null cells). Since, as is demonstrated in the accompanying report, effector surface Fc receptors play a critical role in the mediation of antibody-dependent cellular cytotoxicity directed at HSV-infected target cells, the major mononuclear effector cell in human blood is a K cell.

Antibody Specificity↗

PubMed2026

Tumor-associated macrophages display differential protein cargo sorting in extracellular vesicles associated with poor survival in ovarian cancer.

Ovarian cancer (OC) progression and metastasis are promoted by ascites, which constitutes a central part of the tumor microenvironment (TME). In this fluid, tumor-associated macrophages (TAMs) represent a prominent immune cell type. In addition to tumor and other host cells such as TAMs, ascites is highly enriched in soluble factors as well as extracellular vesicles (EVs). How TAMs contribute to the EV compartment of the OC TME remains, however, underexplored. In this work peripheral blood monocytes from healthy donors were differentiated into monocyte-derived macrophages (MDMs) and polarized into classically activated (M1-like), alternatively activated (M2-like) and TAM-like (by ascites incubation). For all subtypes, serum-free conditioned medium was collected for 24 h and EVs were isolated and characterized by nano-flow cytometry (nFC), label-free mass spectrometry-based proteomics and electron microscopy, among others. Our results demonstrated distinct traits for EV release and cargo across the different macrophage subtypes. Specifically, TAM-like macrophages exhibited impaired release of small EVs and reduced frequency of tetraspanin-positive particles. These EV subpopulations displayed sizing profiles closer to M1-like than to M2-like samples. Also, the low EV release in TAM-like MDMs was accompanied by altered expression of biogenesis-related markers like flotillin-1 (FLOT1) and a decreased N-glycosylation of CD63 protein, which was validated in patient-derived samples. Remarkably, the EV-associated proteome of TAMs displayed significant enrichment in both pro- and anti-inflammatory molecules with clinical value. Markers significantly enriched in the ascites TAM-EV signature were mostly associated with poor prognosis, whereas M1-like EV-related markers (pro-inflammatory) were mostly associated with longer survival. Our results confirmed previous data for proteins like CD163 and MRC1 to be associated to TAM-EVs, while also describing novel candidates with diagnostic (i.e., COLEC12) and/or prognostic (i.e., MSR1) value in plasma. Taken together, our data support a unique secretory profile of TAMs in OC and provide new EV-associated biomarkers with translational impact. Our results pave the way for a better understanding of the mechanisms behind TAM-EV cargo loading and function, and how these cells participate in the TME landscape.

Humans↗

PubMed1976

Interaction of C-reactive protein with lymphocytes and monocytes: complement-dependent adherence and phagocytosis.

The serum constituent C-reactive protein (CRP), which activates the classical complement (C) pathway when reacting with its substrates, was examined for its ability to mediate reactions of opsonic adherence and phagocytosis. Erythrocytes coated with C-polysaccharide (CPS) and reacted with CRP (E. CPS-CRP) failed to adhere to B cells and displayed only minimal adherence to monocytes. However, upon the addition of absorbed C or purified C components these cells were found to possess the cleavage products C4b and C3b, which in turn resulted in attachment of these cells to both human B lymphocytes and peripheral blood monocytes. E. CPS-CRP treated with C in the absence of antibody were readily phagocytosized by glass-adherent human monocytes. The phagocytosis of E. CPS-CRP-C was not only mediated by CRP but also required the presence of CRP on the surface of the red cells. The extent of ingestion was proportional to the amount of CRP on the red cell intermediate and was reduced by blocking monocyte receptors with aggregated human gamma-globulin (HGG) at concentrations which did not impair the uptake of other particles. The mediation by CRP of reactions of opsonic adherence and phagocytosis as outlined in these studies points to a significant role for CRP in reactions of host defense and inflammation.

C-Reactive Protein↗

PubMed2026

Complement Activation Linked to Type II Interferon Signaling in Still Disease.

OBJECTIVE: Still disease (SD) is an autoinflammatory syndrome characterized by innate immune dysregulation. Although complement can drive inflammation, its involvement in SD remains to be defined. Thus, we aimed to assess complement activation in SD. METHODS: Complement was assessed using transcriptomic, proteomic, and in vitro approaches. RNA sequencing of monocytes was performed in healthy donors (n = 15), those with nonsystemic juvenile idiopathic arthritis (JIA; n = 8), patients with SD at onset (n = 19) and remission (n = 18), and those with macrophage activation syndrome (n = 2). Whole-blood NanoString analysis of complement and interferon (IFN)-related gene expression was conducted in patients with SD (active n = 41, inactive n = 33) and JIA (n > 600). Complement products and inflammatory mediators were measured by Luminex and enzyme-linked immunosorbent assay. Functional complement activity was evaluated in SD (active n = 30, inactive n = 67) and JIA sera (n = 12). In vitro assays examined monocytic C1q induction and complement-mediated CD8+ T cell activation. RESULTS: Transcriptomic analysis of monocytes from patients with SD at onset revealed enrichment of the complement cascade compared with patients in remission (adjusted P = 3.7 × 10-36), ranking among the top 10 up-regulated pathways. Classical complement genes (C1QB/C1QC) were markedly up-regulated in onset SD compared with patients with remission SD and JIA. Patients with active SD showed increased C1q, C3a, C5a, and terminal complement complex protein levels, with enhanced functional classical complement activity. Whole-blood C1QB/C1QC expression correlated with IFN-related markers, including interleukin-18, CXCL9, and CXCL10. Recombinant IFN-γ induced monocytic C1q, whereas C1q enhanced IFN-γ production by CD8+ T cells, supporting a feed-forward loop. CONCLUSION: SD is characterized by complement activation with marked up-regulation of C1q, which is closely linked to IFN-γ/type II signaling.

Journal Article↗

PubMed1978

Activation of classical complement pathway by naturally occurring heteroantibodies in normal rabbit serum. Effect on subpopulations of human lymphoid cells.

Heteroantibodies present in normal rabbit serum (NRS) are toxic to human B lymphocytes, T lymphocytes, and monocytes. Even NRS, which exhibits little back ground cytotoxicity for human lymphoid cells in conventional HLA or B-cell lymphocytotoxic assays, can be shown to contain considerable activity by making two modifications in usual procedures: by washing cells in saline or balanced salt solutions devoid of protein or sugar substances, and by increasing incubation time for 1 h to 3--4 h. Using such modifications, the cytotoxic activity of NRS towards human lymphoid cells was investigated and was found to involve activation of the classical complement pathway rather than activation of the alternate complement pathway. Residual unwanted background cytotoxicity of NRS toward human lymphoid cells can be decreased without loss of desired complement activity either by heating NRS for 15 min at 50 degrees C or by mixing NRS with small amounts of normal human serum.

Animals↗