Myeloid Antigens Research Articles

Honing CAR T cells to tackle acute myeloid leukemia.

Acute myeloid leukemia (AML) remains a dismal disease with poor prognosis, particularly in the relapsed/refractory (r/r) setting. Chimeric antigen receptor (CAR) therapy has yielded remarkable clinical results in other leukemias and thus has, in principle, the potential to achieve similar outcomes in r/r AML. Re-directing the approved CD19-specific CAR designs against the myeloid antigens CD33, CD123 or CLEC12A has occasionally yielded morphological leukemia-free states (MLFS) but has so far been marred by threatening myeloablation and early relapses. These safety and efficacy limitations owe in large part to the challenge of identifying suitable target antigens and designing adequate receptors for effective recognition and safe elimination of AML. Building on lessons learned from the initial clinical attempts, a new wave of CAR strategies relying on alternative target antigens and innovative CAR designs is about to enter clinical evaluation. Adapted multi-antigen targeting, logic-gating and emerging cell engineering solutions offer new possibilities to better direct T cell specificity and sensitivity towards AML. Pharmacologic modulation and genetic epitope engineering may extend these approaches by augmenting target expression in AML cells or minimizing target expression in normal hematopoietic cells. On/off switches or CAR T cell depletion may curb excessive or deleterious CAR activity. Investigation of AML-intrinsic resistance and leukemic microenvironmental factors is poised to reveal additional targetable AML vulnerabilities. We summarize here the findings, challenges and new developments of CAR therapy for AML. These illustrate the need to specifically adapt CAR strategies to the complex biology of AML to achieve better therapeutic outcomes.

Comprehensive single-cell profiling of monocytes in HLA-B27-positive ankylosing spondylitis with acute anterior uveitis.

Acute anterior uveitis (AAU) is a common extra-articular manifestation of ankylosing spondylitis (AS), particularly in patients positive for the human leucocyte antigen (HLA)-B27 genetic marker. To explore the underlying mechanisms of HLA-B27+ AS-associated AAU, we employed single-cell RNA sequencing to profile the transcriptomes of peripheral blood mononuclear cells in three HLA-B27+ AS-associated AAU patients and three healthy controls (HCs). We identified 11 distinct immune cell clusters, with a particular focus on monocytes, revealing six subsets, including three previously unidentified subsets, namely, GTPase immune-associated proteins, Th17-related, and lncRNA monocytes, with unique gene expression patterns. Significant differences in monocyte composition, activation states, and gene expression were observed between patients and HCs, particularly within HLA monocyte subpopulations. Notably, enhanced expression of X-inactive specific transcript and myeloid cell nuclear differentiation antigen genes was validated across monocyte subclusters in patients. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis highlighted significant enrichment in antigen processing and presentation pathways, shedding light on the disease's molecular mechanisms. These findings provide novel insights into the molecular mechanisms of HLA-B27+ AS-associated AAU and may contribute to the development of targeted diagnostic and therapeutic strategies. Further clinical validation is essential.

The Role of miR-155 in Modulating Gene Expression in CD4+ T Cells: Insights into Alternative Immune Pathways in Autoimmune Encephalomyelitis.

CD4+ T cells are considered the main orchestrators of autoimmune diseases. Their disruptive effect on CD4+ T cell differentiation and the imbalance between T helper cell populations can be most accurately determined using experimental autoimmune encephalomyelitis (EAE) as an animal model of multiple sclerosis (MS). One epigenetic factor known to promote autoimmune inflammation is miRNA-155 (miR-155), which is significantly upregulated in inflammatory T cells. The aim of the present study was to profile the transcriptome of immunized mice and determine their gene expression levels based on mRNA and miRNA sequencing. No statistically significant differences in miRNA profile were observed; however, substantial changes in gene expression between miRNA-155 knockout (KO) mice and WT were noted. In miR-155 KO mice, mRNA expression in CD4+ T cells changed in response to immunization with the myeloid antigen MOG35-55. After restimulation with MOG35-55, increased Ffar1 (free fatty acid receptor 1) and Scg2 (secretogranin-2) expression were noted in the CD4+ T cells of miR-155-deficient mice; this is an example of an alternative response to antigen stimulation.

Blood transcriptome profiling reveals distinct gene networks induced by mRNA vaccination against COVID-19.

Messenger RNA (mRNA) vaccines represent a new class of vaccines that has been shown to be highly effective during the COVID-19 pandemic and that holds great potential for other preventative and therapeutic applications. While it is known that the transcriptional activity of various genes is altered following mRNA vaccination, identifying and studying gene networks could reveal important scientific insights that might inform future vaccine designs. In this study, we conducted an in-depth weighted gene correlation network analysis of the blood transcriptome before and 24h after the second and third vaccination with licensed mRNA vaccines against COVID-19 in humans, following a prime vaccination with either mRNA or ChAdOx1 vaccines. Utilizing this unsupervised gene network analysis approach, we identified distinct modular networks of co-varying genes characterized by either an expressional up- or downregulation in response to vaccination. Downregulated networks were associated with cell metabolic processes and regulation of transcription factors, while upregulated networks were associated with myeloid differentiation, antigen presentation, and antiviral, interferon-driven pathways. Within this interferon-associated network, we identified highly connected hub genes such as STAT2 and RIGI and associated upstream transcription factors, potentially playing important regulatory roles in the vaccine-induced immune response. The expression profile of this network significantly correlated with S1-specific IgG levels at the follow-up visit in vaccinated individuals. Those findings could be corroborated in a second, independent cohort of mRNA vaccine recipients. Collectively, results from this modular gene network analysis enhance the understanding of mRNA vaccines from a systems immunology perspective. Influencing specific gene networks could lead to optimized vaccines that elicit augmented vaccine responses.

Comparative Evaluation of the Immunophenotypic Profile of Acute Lymphoblastic Leukaemia in Adult and Paediatric Age Groups in Iraq

Background: Immunophenotyping is a primary tool for investigating acute lymphoblastic leukemia (ALL). Acute lymphoblastic leukemia accounts for 75 - 80% of pediatric leukemia cases and 14% of adult leukemia cases. However, the prognostic factors, treatment strategies, and pathogenic pathways differ between these groups. Objectives: This study aims to compare the pattern of antigen expression between adult and pediatric ALL patients in the Iraqi population and to evaluate the frequency of aberrant myeloid antigen expression in both groups. Methods: A total of 131 patients with de-novo ALL were studied from May 2014 to May 2015. The diagnosis of ALL was confirmed by morphology and immunophenotyping of peripheral blood and bone marrow aspirate specimens using a panel of fluorochrome-labeled antibodies in 6 - colored flow cytometry. Results: The B-ALL phenotype was prevalent in 44 (68.7%) of adult patients compared to 51 (76.1%) in the pediatric group. CD10 expression was present in 49 (76.6%) of adults, mostly with B-ALL. The pediatric group had lower CD10 expression in T-ALL (P = 0.039). CD20 expression was significantly lower in adults compared to children. In T-ALL, significant differences between adult and pediatric groups were observed in CD1a and CD2 expression. Aberrant myeloid antigen expression was present in 29 (45.3%) adults and 30 (44.8%) pediatric patients, with CD33 and CD13 being the most prevalent in both groups. Conclusions: There was an increased T-cell lineage and aberrant antigen expression in both adult and pediatric ALL cases in this Iraqi sample. Adults with ALL tend to display higher levels of CD20 and lower levels of CD1a and CD2 compared to children, markers associated with poorer prognoses.

Site-discordant expression of myeloid cell nuclear differentiation antigen in blastic plasmacytoid dendritic cell neoplasm

Abstract Objectives Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic neoplasm that can show clinical, morphologic, and immunophenotypic overlap with acute myeloid leukemia. Myeloid cell nuclear differentiation antigen (MNDA) is a nuclear protein expressed by myelomonocytic cells previously reported to be reliably absent in BPDCN and proposed as a useful adjunct for the distinction of BPDCN and acute myeloid leukemia. We encountered a case of BPDCN that showed strong nuclear expression of MNDA in bone marrow and breast samples and weak to absent expression in skin samples, prompting us to reevaluate the expression of MNDA in BPDCN. Methods We collected all available BPDCN cases from the Stanford University archives collected in the past 10 years and subjected them to MNDA immunohistochemistry. In select cases, molecular profiling by next-generation sequencing was performed. Results We found 4 cases (of 8 total examined [50%]) with convincing site-discordant MNDA expression. This expression was seen in 3 of 6 (50%) bone marrow samples, 1 of 2 (50%) breast soft tissue samples, and 3 of 14 (up to 21%) skin samples and was not obviously predicted by age, sex, history of myeloid neoplasm, or treatment history. In 2 cases, MNDA was strongly expressed in 2 distinct sites (breast/bone marrow, skin/bone marrow) and negative in subsequent samples. Conclusions Our findings suggest that MNDA expression in BPDCN is anatomic site dependent and transient, with noncutaneous infiltrates showing more frequent expression than cutaneous infiltrates. These results caution against the use of MNDA to exclude BPDCN when considering the differential diagnosis of a blastic extramedullary infiltrate.

Immunophenotypic Characteristics and Cytogenetic Analysis of Adolescent and Young Adult B-Cell Acute Lymphoblastic Leukemia: Correlations With Clinicopathological Parameters.

Introduction Acute lymphoblastic leukemia (ALL) has suboptimal survival rates for adolescents and young adults (AYA) as compared to children. Very limited studies have been conducted on AYA patients in India. This study aimed to identify the cytogenetic and immunophenotype characteristics of B-cell ALL (B-ALL) in AYA patients and determine its correlation with clinicopathological parameters in the Southern India region. Method The study was a prospective study conducted for three years, from June 2019 to May 2022, in India. Newly diagnosed 90 patients with AYA (13-40 years) ALL were recruited. A B-ALL diagnosis was made based on morphology with cytochemical stains and immunophenotype by flow cytometry (FCM). Cytogenetic analysis was also performed using karyotyping and fluorescent in situ hybridization to identify chromosomal aberrations. The cytogenetics results were correlated with immunophenotyping and clinicopathological characteristics. Variables were analyzed using the Mann-Whitney U test and Chi-square test using IBM SPSS Statistics for Windows, Version 20.0 (Released 2011; IBM Corp., Armonk, NY, USA). Results The mean age was 22.68 ± 8.06 years. It was observed that the most common structural chromosomal abnormality for AYA was t(9;22) in 14 (15%) cases, followed by 6q deletions in seven (8%) cases, t(1;19) in four (4%) cases, and t(12;17) and t(6;14) in two (2%) cases each. In addition, t(3;12), t(2;11), t(12;21), t(1;9), t(2;12), and t(X;10) were found in one (1%) case each. The most common numerical abnormality was hyperdiploidy (15; 17%), followed by hypodiploidy (10; 11%). Further, myeloid antigen expression of CD33 was the most common aberrantly expressed marker found in 20 (28%) cases, followed by CD15 in three cases (5%), CD13 in three (4%) cases, and CD11b in two (3%) cases. It was also observed that in Ph+ve cases, CD33 and CD13 were most commonly expressed in three (33%) and two (17%) cases, respectively. In contrast, in Ph-ve patients, their expressions were lesser at 17 (27%) and one (2%) cases, respectively. In addition, leukemia-associated immunophenotype pattern (LAIP) markers CD44 6 (86%) and CD123 5 (55%) were also found to be significantly associated with Ph+ve, whereas their values in the Ph-ve group were lesser at 25 (42%) and 9 (17%), respectively. Our data also showed that older age wassignificantly associated with Ph+ve with a median age of 30 years (p = 0.012). In comparison, the median age of Ph-ve was only 21 years. Conclusion Our study established that the incidence of cytogenetic abnormalities for AYA was consistent with previously reported data. This study reaffirms that Ph+ve cases have significant associations with MyAg (CD13), LAIP (CD123 and CD44), and older age for the South Indian population.

Genetic and clinical characteristics of acute B-cell lymphoblastic leukemia with MEF2D fusions and report of two novel MEF2D rearrangements.

The MEF2D rearrangement is a recurrent chromosomal abnormality detected in approximately 2.4-5.3% of patients with acute B-cell lymphoblastic leukemia (B-ALL). Currently, MEF2D-rearranged B-ALL is not classified as an independent subtype in the WHO classification. Consequently, the clinical significance of MEF2D rearrangement in B-ALL remains largely unexplored. In this study, we retrospectively screened 260 B-ALL patients with RNA sequencing data collected between November 2018 and December 2022. Among these, 10 patients were identified with MEF2D rearrangements (4 with MEF2D::HNRNPUL1, 3 with MEF2D::BCL9, 1 with MEF2D::ARID1B, 1 with MEF2D::DAZAP1 and 1 with MEF2D::HNRNPM). Notably, HNRNPM and ARID1B are reported as MEF2D fusion partners for the first time. The patient with the MEF2D::HNRNPM fusion was resistant to chemotherapy and chimeric antigen receptor T-cell therapy and relapsed early after allogenic stem cell transplantation. The patient with MEF2D::ARID1B experienced early extramedullary relapse after diagnosis. All 10 patients achieved complete remission after induction chemotherapy. However, 9/10 (90%) of whom experienced relapse. Three of the 9 patients relapsed with aberrant expression of myeloid antigens. The median overall survival of these patients was only 11 months. This small cohort showed a high incidence of early relapse and short survival in patients with MEF2D rearrangements.

Clinicohematological profile and immunophenotypic patterns of childhood acute leukemia: Prognostic correlation

Acute leukemia (AL) presents a heterogeneous molecular profile, requiring precise diagnostic categorization and subcategorization. The present study aims to estimate the clinicohematological profile and immunophenotypic pattern of childhood AL while conducting prognostic assessments. This cross-sectional study analyzed a total of 68 samples of AL collected from January 2019 to June 2021. The male-to-female ratio was 4.6:1, with a mean age of 6.6 ± 3.4 years. Total leukocyte count (TLC) was significantly increased in all types of AL (P = 0.03). The median value (interquartile range) of TLC (×106/dL) was 8,450 (4,100 – 27,950), with blast counts in peripheral smears at 59 (24 – 80), and in bone marrow aspirates (BMAs) at 95 (75 – 98). There was a significant association (P < 0.001) and a strong association (C = 0.9110) between the morphology of BMA with immunophenotype. Based on immunophenotype, AL was categorized into four groups: B-cell acute lymphoblastic leukemia (B-ALL) (51.5%), T-cell acute lymphoblastic leukemia (T-ALL) (10.3%), AML (22%), and mixed phenotype AL (MPAL) (16.2%). Furthermore, eight subgroups were identified: B lineage, Ia-Common-B-ALL (88.6%) and Ib-Pre-B-ALL (11.4%); T-lineage, IIa-Cortical T-ALL (71.4%) and IIb-Pre-T-ALL (28.6%); AML subgroups, IIIa-M2 (73.93%) and III-M4 (26.7%); and MPAL subgroups, IVa-aberrant expression of myeloid antigens in B-ALL (90.9%), and IVb-aberrant expression of lymphoid markers in AML (9.1%). A poor prognostic immunophenotype (T-ALL, AML) was significantly (P = 0.023) more prevalent in deceased patients with AL. The highest mortality rate was observed in AML (86.4%), followed by T-ALL (57.2%). The most common immunophenotype observed was Common-B-ALL in childhood AL, and a poor prognostic immunophenotype (T-ALL and AML) with the highest mortality rate was found in AML. Thus, knowledge about clinicohematological and immunophenotypic patterns will aid in patient management.

Green synthesis of ultrafine gold nanoparticles from sweet flag (Acorus calamus) for effective anti-leukemic, anti-urolithiatic and in silico docking studies

Gold nanoparticles (AuNPs) are emerging effective biomaterials which play a vital role in the biodiversity research area due to their biocompatibility, and less toxic nature. The AuNPs of various sizes and shapes have vibrant optical features that can be utilized for a variety of imaging and therapeutic applications. Acorus calamus (A. calamus) has been used in traditional medical systems as a general tonic for centuries. It is thought to have potential benefits in the treatment of digestive disorders and respiratory problems. In Kerala, newborns were given a nanogram of (A. calamus) rhizome paste to increase oral cleanliness and improve their health and immunity. This prompted us to produce AuNPs by A. calamus and to explore their concealed pharmacological properties. In this work, we used a simple sonication method to synthesise blue-coloured AuNPs using sweet flag (A. calamus) extract, which acted as a stabilising and reducing agent at ambient temperature. The formation and morphology of the AC-AuNPs was confirmed by XRD, TEM, EDX, FT-IR and UV–vis spectral techniques. Anti-leukemic and anti-urolithiatic activities of the AC-AuNPs were also investigated. The anti-leukemic results revealed cytomorphological changes like cancer cell membrane lyses and coiling in Human myelogenous leukemia cells (K562) and exhibited IC50 at a concentration of 41.45 µg/mL. Furthermore, in vitro DNA binding assay of AC-AuNPs with calf-thymus were conducted. The anti-urolithiatic activity of AC-AuNPs suggests a dose-dependent suppression of calcium oxalate method (COM) crystals nucleation and aggregation. These results suggest that AC-AuNPs have potent antileukemic and anti-urolithiatic activities. In silico docking results revealed that eugenol, α-asarone and calamenene possess good binding scores with myeloid cell surface antigen (CD33) and estrogen receptors, respectively. In vitro anticancer and DNA binding studies have endorsed the capping nature of AC-AuNPs by these phytoconstituents, which is validated by docking analysis.

CAR-T Cells in Acute Myeloid Leukemia: Where Do We Stand?

Despite recent advances, the prognosis of acute myeloid leukemia (AML) remains unsatisfactory due to disease recurrence and the development of resistance to both conventional and novel therapies. Engineered T cells expressing chimeric antigen receptors (CARs) on their cellular surface represent one of the most promising anticancer agents. CAR-T cells are increasingly used in patients with B cell malignancies, with remarkable clinical results despite some immune-related toxicities. However, at present, the role of CAR-T cells in myeloid neoplasms, including AML, is extremely limited, as specific molecular targets for immune cells are generally lacking on AML blasts. Besides the paucity of dispensable targets, as myeloid antigens are often co-expressed on normal hematopoietic stem and progenitor cells with potentially intolerable myeloablation, the AML microenvironment is hostile to T cell proliferation due to inhibitory soluble factors. In addition, the rapidly progressive nature of the disease further complicates the use of CAR-T in AML. This review discusses the current state of CAR-T cell therapy in AML, including the still scanty clinical evidence and the potential approaches to overcome its limitations, including genetic modifications and combinatorial strategies, to make CAR-T cell therapy an effective option for AML patients.

Virion-incorporated CD14 enables HIV-1 to bind LPS and initiate TLR4 signaling in immune cells.

HIV-1 has a broad range of nuanced interactions with the immune system, and the incorporation of cellular proteins by nascent virions continues to redefine our understanding of the virus-host relationship. Proteins located at the sites of viral egress can be selectively incorporated into the HIV-1 envelope, imparting new functions and phenotypes onto virions, and impacting viral spread and disease. Using virion capture assays and western blot, we show that HIV-1 can incorporate the myeloid antigen CD14 into its viral envelope. Virion-incorporated CD14 remained biologically active and able to bind its natural ligand, bacterial lipopolysaccharide (LPS), as demonstrated by flow virometry and immunoprecipitation assays. Using a Toll-like receptor 4 (TLR4) reporter cell line, we also demonstrated that virions with bound LPS can trigger TLR4 signaling to activate transcription factors that regulate inflammatory gene expression. Complementary assays with THP-1 monocytes demonstrated enhanced secretion of inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and the C-C chemokine ligand 5 (CCL5), when exposed to LPS-loaded virus. These data highlight a new type of interplay between HIV-1 and the myeloid cell compartment, a previously well-established cellular contributor to HIV-1 pathogenesis and inflammation. Persistent gut inflammation is a hallmark of chronic HIV-1 infection, and contributing to this effect is the translocation of microbes across the gut epithelium. Our data herein provide proof of principle that virion-incorporated CD14 could be a novel mechanism through which HIV-1 can drive chronic inflammation, facilitated by HIV-1 particles binding bacterial LPS and initiating inflammatory signaling in TLR4-expressing cells.IMPORTANCEHIV-1 establishes a lifelong infection accompanied by numerous immunological changes. Inflammation of the gut epithelia, exacerbated by the loss of mucosal T cells and cytokine dysregulation, persists during HIV-1 infection. Feeding back into this loop of inflammation is the translocation of intestinal microbes across the gut epithelia, resulting in the systemic dissemination of bacterial antigens, like lipopolysaccharide (LPS). Our group previously demonstrated that the LPS receptor, CD14, can be readily incorporated by HIV-1 particles, supporting previous clinical observations of viruses derived from patient plasma. We now show that CD14 can be incorporated by several primary HIV-1 isolates and that this virion-incorporated CD14 can remain functional, enabling HIV-1 to bind to LPS. This subsequently allowed CD14+ virions to transfer LPS to monocytic cells, eliciting pro-inflammatory signaling and cytokine secretion. We posit here that virion-incorporated CD14 is a potential contributor to the dysregulated immune responses present in the setting of HIV-1 infection.

MNDA expression and its value in differential diagnosis of B-cell non-Hodgkin lymphomas: a comprehensive analysis of a large series of 1293 cases.

MNDA (myeloid nuclear differentiation antigen) has been considered as a potential diagnostic marker for marginal zone lymphoma (MZL), but its utility in distinguishing MZL from other B-cell non-Hodgkin lymphomas (B-NHLs) and its clinicopathologic relevance in diffuse large B-cell lymphoma (DLBCL) are ambiguous. We comprehensively investigated MNDA expression in a large series of B-NHLs and evaluated its diagnostic value. MNDA expression in a cohort of 1293 cases of B-NHLs and 338 cases of reactive lymphoid hyperplasia (RLH) was determined using immunohistochemistry and compared among different types of B-NHL. The clinicopathologic relevance of MNDA in DLBCL was investigated. MNDA was highly expressed in MZLs (437/663, 65.9%), compared with the confined staining in marginal zone B-cells in RLH; whereas neoplastic cells with plasmacytic differentiation lost MNDA expression. MNDA expression was significantly higher in mantle cell lymphoma (MCL, 79.6%, p = 0.006), whereas lower in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL, 44.8%, p = 0.001) and lymphoplasmacytic lymphoma (LPL, 25%, p = 0.016), and dramatically lower in follicular lymphoma (FL, 5.2%, p < 0.001), compared with MZL. 29.6% (63/213) of DLBCLs were positive for MNDA. The cases in non-GCB group exhibited a higher rate of MNDA positivity (39.8%) compared to those in GCB group (16.3%) (p < 0.001), and MNDA staining was more frequently observed in DLBCLs with BCL2/MYC double-expression (50%) than those without BCL2/MYC double-expression (24.8%) (p = 0.001). Furthermore, there was a significant correlation between MNDA and CD5 expression in DLBCL (p = 0.036). MNDA was highly expressed in MZL with a potential utility in differential diagnosis between MZL and RLH as well as FL, whereas its value in distinguishing MZL from MCL, CLL/SLL is limited. In addition, MNDA expression in DLBCL was more frequently seen in the non-GCB group and the BCL2/MYC double-expression group, and demonstrated a correlation with CD5, which deserves further investigation. The clinical relevance of MNDA and its correlation with the prognosis of these lymphomas also warrant to be fully elucidated.

MNDA, a PYHIN factor involved in transcriptional regulation and apoptosis control in leukocytes.

Inflammation control is critical during the innate immune response. Such response is triggered by the detection of molecules originating from pathogens or damaged host cells by pattern-recognition receptors (PRRs). PRRs subsequently initiate intra-cellular signalling through different pathways, resulting in i) the production of inflammatory cytokines, including type I interferon (IFN), and ii) the initiation of a cascade of events that promote both immediate host responses as well as adaptive immune responses. All human PYRIN and HIN-200 domains (PYHIN) protein family members were initially proposed to be PRRs, although this view has been challenged by reports that revealed their impact on other cellular mechanisms. Of relevance here, the human PYHIN factor myeloid nuclear differentiation antigen (MNDA) has recently been shown to directly control the transcription of genes encoding factors that regulate programmed cell death and inflammation. While MNDA is mainly found in the nucleus of leukocytes of both myeloid (neutrophils and monocytes) and lymphoid (B-cell) origin, its subcellular localization has been shown to be modulated in response to genotoxic agents that induce apoptosis and by bacterial constituents, mediators of inflammation. Prior studies have noted the importance of MNDA as a marker for certain forms of lymphoma, and as a clinical prognostic factor for hematopoietic diseases characterized by defective regulation of apoptosis. Abnormal expression of MNDA has also been associated with altered levels of cytokines and other inflammatory mediators. Refining our comprehension of the regulatory mechanisms governing the expression of MNDA and other PYHIN proteins, as well as enhancing our definition of their molecular functions, could significantly influence the management and treatment strategies of numerous human diseases. Here, we review the current state of knowledge regarding PYHIN proteins and their role in innate and adaptive immune responses. Emphasis will be placed on the regulation, function, and relevance of MNDA expression in the control of gene transcription and RNA stability during cell death and inflammation.

Abstract 2377: HER2-ADC efficacy is rooted in its induction of immunogenic cell death with FcGR activation and a systemic bystander effect

Abstract Background: T-DXd is an antibody-drug conjugate (ADC) targeting HER2 that has demonstrated superior clinical efficacy over previous HER2-targeting agent Trastuzumab emtansine (T-DM1). Notably, T-Dxd is clinically effective in breast cancers (BC) with a range of HER2 expression. While its purported mechanism of action (MOA) involves its cleavable linker leading to bystander killing, it remains unclear how this potential MOA accounts for efficacy in HER2-low cancers or the role FCGR-mediated signaling and immune induction plays in its clinical efficacy. Method: In vitro studies utilized co-culture, internalization, FCGR activation, ADCP, flow cytometry, and gene expression by QRT-PCR and ELISA assays. Assessments of tumor antigen-specific T cell stimulation involved JEDI T cells. In vivo studies were conducted using in vivo implantation of HER2+ and HER2- cells, PK assessments of T-Dxd/DM1 and therapeutic effects determined using an endogenous HER2 transgenic mouse model that measured HER2-specific adaptive immune responses, in combination with immune checkpoint blockade anti-CD47. Results: T-Dxd elicited a systemic bystander effect that was only partially dependent on HER2 expression, mediated by specific cathepsins in the extracellular TME. Notably, T-Dxd cytotoxicity induced immunogenic cell death (ICD), while also retaining the ability to engage FCGRs to promote ADCP and innate immune activation. ICD was mediated by secretion of specific Dxd driven DAMPs (HMGB1 and eATP), resulting in TLR4/STING activation. ICD and FCGR activation along with antigen ADCP together elicited myeloid cell activation (CD80, CD40) and antigen presentation, resulting in effective expansion of tumor antigen-specific T cells responses, demonstrated by co-culture assays using EGFP/HER2+ BC cells and CD8+ JEDI T cells. T cell activation required TLR4 and STING pathways while in vivo, T-Dxd anti-tumor responses associated with augmented HER2-specific T and B cell responses. However, T-Dxd also induced CD47 to limit phagocytosis. But, the use of CD47/SIRPa blocking antibodies dramatically enhanced CD8+ T cell expansion in vitro and anti-tumor efficacy in vivo upon T-Dxd treatment. Conclusion: Our study demonstrates that T-Dxd is cleavable in HER2 negative BC in vivo, which permits more widespread Dxd activity against HER2 low BC. Critically, Dxd elicits ICD, resulting in innate immune stimulation of myeloid cells, which when combined with FCGR activation and ADCP, leads to a striking induction of tumor-specific adaptive immunity. This combination was unique to T-Dxd, which may underlie its clinical superior efficacy. However, T-Dxd activity also elicits suppressive CD47 expression which could be negated using CD47/SIRPA blockade. We found that this combination dramatically enhanced T-Dxd resulted therapeutic efficacy, thus supporting clinical exploration of these combinations. Citation Format: Li-Chung Tsao, Xingru Ma, John S. Wang, Timothy N. Trotter, Tao Wang, Jun-Ping Wei, Gang-jun Lei, Jason McBane, Ping Fan, Ivan Spasojevic, Zachary C. Hartman. HER2-ADC efficacy is rooted in its induction of immunogenic cell death with FcGR activation and a systemic bystander effect [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2377.

Flow cytometric detection of leukemic blasts in Libyan pediatric patients with acute lymphoblastic leukemia

ABSTRACT The diagnosis of acute lymphoblastic leukemia (ALL), which is the most common type of cancer in children, has become more accurate with the use of flow cytometry. Here, this technology was used to immunophenotype leukemic cells in peripheral blood samples from Libyan pediatric ALL patients. We recruited 152 newly diagnosed patients at Tripoli Medical Center (Tripoli, Libya) by morphological examination of blood and bone marrow. Twenty-three surface and cytoplasmic antigen markers were used to characterize B and T cells in circulating blood cells by four-color flow cytometry. Six children (3.9%) turned out to have biphenotypic acute leukemia, 88 (57.9%) had B ALL, and 58 (38.1%) had T ALL. There were 68 cases of pro-B ALL CD10-positive (44.7%), 8 cases of pro-B ALL CD10-negative (5.2%), 6 cases of pre-B ALL (3.9%), and 6 of mature-B ALL (3.9%). CD13 was the most commonly expressed myeloid antigen in ALL. We present immunophenotypic data for the first time describing ALL cases in Libya. The reported results indicate that the most common subtype was pro-B ALL, and the frequency of T-ALL subtype was higher compared to previous studies. Six cases were positive for both myeloid and B lymphoid markers. Our findings may provide the basis for future studies to correlate immunophenotypic profile and genetic characteristics with treatment response among ALL patients.

Myeloid cell-expressed MNDA enhances M2 polarization to facilitate the metastasis of hepatocellular carcinoma.

Stable infiltration of myeloid cells, especially tumor-associated M2 macrophages, acts as one of the essential features of the tumor immune microenvironment by promoting the malignant progression of hepatocellular carcinoma (HCC). However, the factors affecting the infiltration of M2 macrophages are not fully understood. In this study, we found the molecular subtypes of HCC with the worst prognosis are characterized by immune disorders dominated by myeloid cell infiltration. Myeloid cell nuclear differentiation antigen (MNDA) was significantly elevated in the most aggressive subtype and exhibited a positively correlation with M2 infiltration and HCC metastasis. Moreover, MNDA functioned as an independent prognostic predictor and has a good synergistic effect with some existing prognostic clinical indicators. We further confirmed that MNDA was primarily expressed in tumor M2 macrophages and contributed to the enhancement of its polarization by upregulating the expression of the M2 polarization enhancers. Furthermore, MNDA could drive the secretion of M2 macrophage-derived pro-metastasis proteins to accelerate HCC cells metastasis both in vivo and in vitro. In summary, MNDA exerts a protumor role by promoting M2 macrophages polarization and HCC metastasis, and can serve as a potential biomarker and therapeutic target for HCC.

ASSOCIATION OF THE PRESENCE OF BCR-ABL1 GENE REARRANGEMENTS AND MYELOID ABERRANT ANTIGENS IN PRECURSOR B-ACUTE LYMPHOBLASTIC LEUKEMIA (PRE-B-ALL) PATIENTS

Objective: To determine the association of the presence of BCR-ABL1 gene rearrangements and myeloid aberrant antigens in precursor B-ALL patients. Material and Methods: Both males and females, of all age groups, diagnosed with precursor B-ALL on flow cytometry were included in the study. BCR-ABL1 gene rearrangement was identified by performing Fluorescence in situ hybridization (FISH) using Vysis LSI BCR/ABL, Dual color, Dual fusion translocation probe set. The results were noted and compared with the results of flow cytometry. Results: Male patients were 36 (60%) and female patients were 24 (40%) out of total 60 patients. Median age was 22 years (range 1-73). BCR-ABL1 fusion gene was identified in 47 (78%) patients while 13 (22%) patients were negative for BCR-ABL1. Aberrant myeloid antigens were expressed in 24 (40%) patients and all of these patients were BCR-ABL1 positive. None of BCR-ABL1 negative patients expressed aberrant antigens. There was statistically significant association between BCR-ABL1 positivity and CD117 expression (P&lt;0.05). Conclusion: Keywords: BCR-ABL1, Pre B-ALL, Myeloid aberrant antigens, Flow cytometry, FISH.

Harnessing T cell exhaustion and trogocytosis to isolate patient-derived tumor-specific TCR.

To study and then harness the tumor-specific T cell dynamics after allogeneic hematopoietic stem cell transplant, we typed the frequency, phenotype, and function of lymphocytes directed against tumor-associated antigens (TAAs) in 39 consecutive transplanted patients, for 1 year after transplant. We showed that TAA-specific T cells circulated in 90% of patients but display a limited effector function associated to an exhaustion phenotype, particularly in the subgroup of patients deemed to relapse, where exhausted stem cell memory T cells accumulated. Accordingly, cancer-specific cytolytic functions were relevant only when the TAA-specific T cell receptors (TCRs) were transferred into healthy, genome-edited T cells. We then exploited trogocytosis and ligandome-on-chip technology to unveil the specificities of tumor-specific TCRs retrieved from the exhausted T cell pool. Overall, we showed that harnessing circulating TAA-specific and exhausted T cells allow to isolate TCRs against TAAs and previously not described acute myeloid leukemia antigens, potentially relevant for T cell-based cancer immunotherapy.

Retrospective Immunophenotypic Profile of Acute Leukemias in the State of Rio Grande Do Norte, Northeast, Brazil

INTRODUCTION:The main acute leukemias (ALs) are lymphoid (B or T lineage ALL) and myeloid (AML), in addition to biphenotype AL (BAL) and undifferentiated ALL (IAL), which are rarer. This variation reflects on therapy, requiring methods to characterize these leukemias. Thus, methods such as immunophenotyping by flow cytometry (ICF), multiparametric and quantitative, help in the follow-up of these neoplasms. Objective: The aim of this study was to demonstrate the immunophenotypic diagnostic profiles in patients with AL in Rio Grande do Norte, state, Brazil by FC. Methodology: Bone marrow and peripheral blood samples from 371 patients clinically diagnosed with AL were investigated by CF, using a panel of monoclonal antibodies for the detection of lymphoid (B, T and NK) and myeloid antigens, as well as markers related to cell immaturity such as CD34, Terminal deoxynucleotidyl Transferase (TdT).At the same time, information related to clinical data, age group and sex of patients was also collected. Results: Of all LA investigates 71 were B cell-ALL, 55 T cell-ALL, 239 AML, 04 BAL and 02 IAL. Regarding the immunophenotypic pattern, the main subgroups in relation to age group and were evidenced through the FC. 06/71 were Pro-B ALL, 48/71 Common ALL, 06/71 cyt mü chain ALL and 11/71 mature sIgM+ B-ALL. In B-cell lineage ALL, 51 (71.8%) of the cases were children (less than or equal to 18 years old) and 20 (28.2%) adults (over 18 years old). In T-cell ALL, 9 (16.4%) were pre-T ALL, 12 (21.8%) intermediate ALL and 29 (52.7%) medullary T-type ALL, corresponding to a total of 36.4% children and 63.6% adults. In AML, there was a predominance of involvement in adult patients, corresponding to47 (80.7%) of cases and 192 (80.3%) in children. Biphenotypic and undifferentiated AL were detected in adult patients. DISCUSSION: The B cell-ALL were characterized by natural arrest of B-cells precursors based on the expression of antigens related to this lineage in: i) Pro-B ALL (CD19+, HLA-Dr+, CD34+, TdT+); ii) Common ALL (CD10+, CD19+, cCD79a+, cytCD22+, HLA-Dr+, TdT+/- and CD34+/-); iii) cyt mü chain+ ALL (cyt IgM+, CD19+, HLA-Dr+, cytCD79a+, cytCD22+, CD10-, CD34-) and iv) mature B-ALL (sIgM+, sCD22+, CD10+/-, CD20+ and kappa+ or lambda+). The T-ALL were classified into: i) pre-T-ALL (CD7+, cytCD3+, HLADr+, CD34+ and TdT+), ii) intermediate T-ALL (CD1a+, CD2+, CD7+, cytCD3+, TdT+ and HLADr+, CD4+/CD8+) and Medullary T-ALL (CD4+ or CD8+, sCD3+, CD1a-, TdT+, HLADr+/- and CD34-). It was also possible to observe the aberrant expression of myeloid antigens in B and T-ALL, such as CD13, CD33 and CD66b, mainly related to ALL in the context of KMT2A rearrangement with lineage switching. In addition to transferrin receptors (CD71) and IL-2 receptor (CD25), which have been reported in the context of ALL BCR+/ABL+, as well as the presence of the Philadelphia chromosome. In AMLs, the most observed subtypes were those with little differentiation and with a monocyte component. (CD64+/CD14+). CD15+/CD34+ expression was also observed, indicative of asynchrony of maturation, and phenotypic aberrancy of lymphoid antigens in some cases, predominantly CD7. In addition to other antigens such as CD2 and CD19, CD19 and CD56, In addition, ALL was more frequent in children and males, while AML in adults and females in general, with a predominant incidence in males among adult patient. Conclusion: When properly applied, ICF can have a great impact on the diagnosis, classification and prognostic analysis of neoplastic processes.