Flow Cytometric Assessment Research Articles

Flow Cytometric Assessment of the Influence of Cryopreservation on Vitality, Recovery and Immunophenotype of Camel Peripheral Blood Mononuclear Cells

Background: Immunophenotyping has been proven a valuable tool in diagnostic and research immunology laboratories to evaluate the immune status in health and disease. However, in some cases, cells cannot be analyzed immediately after separation and must be stored for later analysis. The present study was undertaken to investigate the impact of cryopreservation of camel PBMC on their vitality, recovery, shape, staining patterns with monoclonal antibodies and lymphocyte composition. Methods: Flow cytometry was employed to analyze cell apoptosis, necrosis, shape change, staining patterns with mAbs and cellular composition of freshly separated and cryopreserved camel PBMC. Result: The results showed similar lymphocytes and monocytes absolute numbers with comparable percentages of apoptotic and necrotic cells between fresh and preserved PBMC indicating no significant impact of cryopreservation on the recovery of camel PBMC. Although a cryopreservation-induced shape change was identified for camel lymphocytes, this change did not interfere with the identification of cryopreserved lymphocytes based on their SSC and FSC characteristics. In addition, the reactivity of camel PBMC with mAbs to the cell markers antigens CD45, CD44, CD11a, MHC-I, CD14, CD163 and CD172a remained unchanged for cryopreserved cells. However, mAbs to MHC-II and BAQ44A displayed modified binding to cryopreserved PBMC leading to significant changes in the positively stained B cells and increased MHC-II expression on monocytes. In conclusion, the results of the current study show that storing camel PBMC in cryopreservation media at -80 is an appropriate procedure for preserving the epitopes for all the used mAbs with modified binding to B cell markers.

Flow Cytometric Assessment of FcγRIIIa-V158F Polymorphisms and NK Cell Mediated ADCC Revealed Reduced NK Cell Functionality in Colorectal Cancer Patients.

Antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells is a key mechanism in anti-cancer therapies with monoclonal antibodies, including cetuximab (EGFR-targeting) and avelumab (PDL1-targeting). Fc gamma receptor IIIa (FcγRIIIa) polymorphisms impact ADCC, yet their clinical relevance in NK cell functionality remains debated. We developed two complementary flow cytometry assays: one to predict the FcγRIIIa-V158F polymorphism using a machine learning model, and a 15-color flow cytometry panel to assess antibody-induced NK cell functionality and cancer-immune cell interactions. Samples were collected from healthy donors and metastatic colorectal cancer (mCRC) patients from the FIRE-6-Avelumab phase II study. The machine learning model accurately predicted the FcγRIIIa-V158F polymorphism in 94% of samples. FF homozygous patients showed diminished cetuximab-mediated ADCC compared to VF or VV carriers. In mCRC patients, NK cell dysfunctions were evident as impaired ADCC, decreased CD16 downregulation, and reduced CD137/CD107a induction. Elevated PD1+ NK cell levels, reduced lysis of PDL1-expressing CRC cells and improved NK cell activation in combination with the PDL1-targeting avelumab indicate that the PD1-PDL1 axis contributes to impaired cetuximab-induced NK cell function. Together, these optimized assays effectively identify NK cell dysfunctions in mCRC patients and offer potential for broader application in evaluating NK cell functionality across cancers and therapeutic settings.

Flow-cytometric Analysis of Reactive Oxygen Species in Blood Cells: A Potential Tool for Predicting Restenosis - Insights from a Cohort Study.

In-stent restenosis (ISR) is a recurrence of a blockage in a section of the coronary artery that has previously been treated with a stent. Molecular/biochemical pathways underlying ISR are not fully understood, but inflammation and reactive oxygen species (ROS) induced oxidative stress play a significant role in the pathogenesis of restenosis. As blood cells are highly sensitive to oxidative stress and blood is readily accessible compared to other tissues, the current study flow cytometrically investigated intracellular ROS and cytokine profile of blood cells as possible markers of restenosis. Flow cytometry is commonly used for detecting ROS and analyzing oxidative stress but so far, it has not been utilized for prediction of ISR. So, the aim of the study was to explore the potential of flow cytometric assessment of ROS levels in the blood cells as predictor of ISR. The study was carried out in a total of 60 patients who had previously undergone coronary artery stent implantation. They were categorized as Group I - Coronary stent implanted patients without restenosis (n=30) and Group II - Coronary stent implanted patients with restenosis (n=30). Sociodemographics, biochemical and angiographic characteristics were assessed. Intracellular ROS and cytokine estimation in blood cells was done by using flow cytometric analysis. Flow cytometric measurements demonstrated a 1.3-fold increase in ROS levels in red blood cells (RBCs) and 2-fold increase in ROS levels in leucocytes in group II as compared to group I. Mean serum concentrations of pro-inflammatory cytokines: tumor necrosis factor-α (33.54 ± 6.48 vs. 20.10 ± 5.61, p <0.001***), interferon-gamma (21.76 ± 4.46 vs. 20.10 ± 5.61, p <0.001***), interleukin 6 (152.56 ± 30.67 vs. 113.95 ± 23.38, p <0.001***) were found to be higher in restenotic patients as compared to the non-restenotic patients. Correlation analysis showed that intracellular ROS levels of RBCs exhibited a significant positive correlation with late lumen loss in restenotic (r=0.71, p <0.01) as well as non-restenotic patients (r=0.59, p <0.01). Similarly, intracellular ROS levels of WBCs exhibited a significant positive correlation with late lumen loss in restenotic (r=0.72, p <0.01) as well as non-restenotic patients (r=0.61, p <0.01). This study highlights the role of increased levels of intracellular ROS in blood cells in the subsequent development of ISR, which can be detected flow cytometrically. The study suggests that intracellular ROS estimation in blood cells may serve as a potential marker for restenosis and their flow cytometric analysis may facilitate the prediction of ISR.

In vitro and in silico studies of a Zn(II) complex as a potential therapeutic agent for breast cancer.

Breast cancer (BC) is one of the most life-threatening diseases of women's health worldwide. This work was conducted to assess the anti-BC potency of a new Zn(II)-based complex. The Zn(II) complex coordinated to dimethoxy-substituted bipyridine was synthesized and its molecular structure was elucidated as [Zn(2Meobpy)3](clo4)2 (2Meobpy-Zn) by single-crystal X-ray diffraction, 2Meobpy represents 4,4'-dimethoxy-2,2'-bipyridine. The cytotoxicity results indicated that 2Meobpy-Zn, unlike cisplatin, acts potently and selectively on the human breast cancer cells (MCF-7) compared to normal murine embryo cells (NIH/3T3) by IC50 value of 4.6 ± 0.5µm and selectivity index (SI) of 2.0 over 48h. 2Meobpy-Zn and cisplatin showed anti-metastatic activity as evidenced by inhibition of the colony formation and cell migration. The flow cytometric assessment of MCF-7 cells supported that 2Meobpy-Zn and cisplatin exert their cytotoxic effect through the apoptotic pathway. Moreover, 2Meobpy-Zn could induce overproduction of intracellular reactive oxygen species (ROS) in MCF-7 cells. The apoptotic mechanism in 2Meobpy-Zn-treated MCF-7 cells is probably related to the regulation of apoptosis-relevant genes expression, including BAX and BCL2. Moreover, 2Meobpy-Zn is able to cleave pUC19 plasmid DNA through the hydrolytic reaction pathway. Finally, 2Meobpy-Zn's affinity towards antiapoptosis-related proteins, as a potential apoptosis inducer, as well as breast cancer-relevant proteins, as a potential anti-BC agent, was evaluated by in silico molecular docking studies. Altogether, the results of this work strongly evidenced that 2Meobpy-Zn can be the subject of experimental validation and clinical trials to introduce this complex as a promising BC therapeutic agent.

Combined Phloretin and Human Platelet-rich Plasma Effectively Preserved Integrities of Brain Structure and Neurological Function in Rat after Traumatic Brain Damage

This study investigates whether phloretin, a brain-edema inhibitor, can enhance the therapeutic effects of human-derived platelet-rich plasma (hPRP) in reducing brain hemorrhagic volume (BHV) and preserving neurological function in rodents following acute traumatic brain damage (TBD) Forty rats were divided into five groups: sham-control, TBD, TBD + phloretin (80 mg/kg/dose intraperitoneally at 30 minutes and on days 2/3 post-TBD), TBD + hPRP (80μL by left intra-carotid-artery injection at 3 hours post-TBD), and TBD + phloretin + hPRP. Cerebral tissues were harvested on day 28 post-TBD for analysis. Brain MRI on day 28 showed the lowest BHV in the sham-control group and the highest in the TBD group. BHV was significantly lower in the phloretin + hPRP group compared to the phloretin or hPRP alone groups, which had similar BHV. Neurological function followed an inverse pattern to BHV. By day 28, protein levels of upstream (HGMB1, TLR-2, TLR-4, MyD88, Mal, TRAM, TRIF, TRAF6, IKK-α, IKK-ß, p-NF-κB) and downstream (IL-1ß, TNF-α, iNOS) inflammation signalings, apoptosis (caspase3, PARP), and fibrosis (Smad3, TGF-ß) biomarkers, as well as flow cytometric assessment of inflammatory cells (CD11b/c+, Ly6G+, PMO+) and early (AN-V+/PI-) and late (AN-V+/PI+) mononuclear-cell apoptosis, displayed patterns similar to BHV. The number of inflammatory (CD68+, MMP9+) and brain-swelling/myelin-damaged (AQP4+, GFAP+) mediators also followed this pattern, while neuronal-myelin (Doublecortin+, NeuN, nestin) mediators showed an inverse relationship with BHV (all p<0.0001). Combined phloretin and hPRP therapy is superior to either treatment alone in protecting the brain against TBD, primarily by suppressing inflammatory signaling and brain-swelling biomarkers.

High proportion of PD-1 and CD39 positive CD8+ tissue resident T lymphocytes correlates with better clinical outcome in resected human oesophageal adenocarcinoma

ObjectiveTo understand the CD8+ tumour infiltrating lymphocyte (TIL) compartment of oesophageal adenocarcinoma (OAC) with regards to markers of lymphocyte exhaustion, tissue residency and to identify possible reasons behind differential responses to therapy.DesignTumour samples from 44 patients undergoing curative resection for OAC were assessed by flow cytometry for presence of antigen-experienced TILs and markers of activation and exhaustion. Populations of PD-1 and CD39 positive OAC TILs were sorted, and bulk RNA sequencing undertaken using a modified SmartSeq2 protocol. Flow cytometric assessment of functionality was completed.ResultsA higher proportion of antigen experienced CD8+ OAC TILs was associated with improved survival following surgery; while, high double positivity (DP) for PD-1 and CD39 among these TILs also correlated significantly with outcome. These DP TILs possess a minority population which is positive for the markers of exhaustion TIM3 and LAG3. Transcriptomic assessment of the PD-1 and CD39 DP TILs demonstrated enrichment for a tissue resident memory T lymphocyte (TRM) phenotype associated with improved survival in other cancers, reinforced by positivity for the canonical TRM marker CD103 by flow cytometry. This population demonstrated maintained functional capacity both in their transcriptomic profile, and on flow cytometric assessment, as well as preserved proliferative capacity.ConclusionResected OAC are variably infiltrated by PD-1 and CD39 DP TILs, an abundance of which among lymphocytes is associated with improved survival. This DP population has an increased, but still modest, frequency of TIM3 and LAG3 positivity compared to DN, and is in keeping with a functionally competent TRM phenotype.

540. INFILTRATION OF RESECTED OESOPHAGEAL ADENOCARCINOMA WITH ANTIGEN-EXPERIENCED PD-1 AND CD39 POSITIVE CD8+ TISSUE RESIDENT MEMORY CELLS CORRELATE WITH IMPROVED SURVIVAL

Abstract Background The development of novel treatments for oesophageal adenocarcinoma (OAC) represents an area of significant unmet need. Despite the application of immune checkpoint blockade alongside chemotherapy as standard of care for some patients with metastatic OAC, responses to immunotherapies are modest and 5-year survival is 17%. The reasons for this remains unclear and while tumour infiltration with CD8+ T lymphocytes (TILs) at the time of resection is associated with improved outcomes, this heterogeneous population remains incompletely characterised in OAC. Tissue resident memory cells (TRM) are increasingly understood as key mediators of immunotherapy response but their role in OAC is poorly understood. Methods Tumour samples were accessed by punch biopsy from the central portion of cancers resected from 44 patients undergoing curative surgery for OAC. Samples were assessed by multi-parametric flow cytometry for the presence of antigen-experienced TILs and markers of activation and exhaustion. Populations of antigen-experienced PD-1 and CD39 positive CD8+ OAC TILs were sorted, and bulk RNA sequencing (RNAseq) undertaken using a modified SmartSeq2 protocol allowing differential gene expression analysis and gene set enrichment analysis. Flow cytometric assessment of functionality was completed. Results Resected OAC are often highly infiltrated with antigen experienced CD8+ TILs expressing high levels of PD-1 and CD39 and an abundance of this population correlates with improved survival (%PD-1/CD39+ &amp;gt;Median, OS HR 0.12). RNAseq of sorted TILs identified this PD-1+ and CD39+ lymphocyte population as enriched for precursor exhausted-like CD8+ TRM (NES 2.01 p=0.00). This is correlated by their CD103+ and TIM3- predominance on flow cytometry in keeping with TRMsassociated with immunotherapy response in other cancers. This population demonstrated a maintained proliferative potential, an ability to degranulate and produce the key effector molecules IFN-γ, TNF-α and Granzyme B. Conclusions An abundance of a PD-1 and CD39 positive CD8+ TIL population, consistent with a precursor exhausted-like TRM population with maintained proliferative and functional capacity, is observed to correlate with improved outcomes following curative surgery for OAC. This TRM population is consistent with analogous populations observed to be responsible for immunotherapy response in other cancers and their identification may predict benefit from such approaches in OAC and allow better patient selection for treatment with immune checkpoint inhibitors.

Immunophenotypical Characterization of Limbal Mesenchymal Stromal Cell Subsets during In Vitro Expansion.

Limbal mesenchymal stromal cells (LMSCs) reside in the limbal niche, supporting corneal integrity and facilitating regeneration. While mesenchymal stem/stromal cells (MSCs) are used in regenerative therapies, there is limited knowledge about LMSC subpopulations and their characteristics. This study characterized human LMSC subpopulations through the flow cytometric assessment of fifteen cell surface markers, including MSC, wound healing, immune regulation, ASC, endothelial, and differentiation markers. Primary LMSCs were established from remnant human corneal transplant specimens and passaged eight times to observe changes during subculture. The results showed the consistent expression of typical MSC markers and distinct subpopulations with the passage-dependent expression of wound healing, immune regulation, and differentiation markers. High CD166 and CD248 expressions indicated a crucial role in ocular surface repair. CD29 expression suggested an immunoregulatory role. Comparable pigment-epithelial-derived factor (PEDF) expression supported anti-inflammatory and anti-angiogenic roles. Sustained CD201 expression indicated maintained differentiation capability, while VEGFR2 expression suggested potential endothelial differentiation. LMSCs showed higher VEGF expression than fibroblasts and endothelial cells, suggesting a potential contribution to ocular surface regeneration through the modulation of angiogenesis and inflammation. These findings highlight the heterogeneity and multipotent potential of LMSC subpopulations during in vitro expansion, informing the development of standardized protocols for regenerative therapies and improving treatments for ocular surface disorders.

Generation of Murine Chimeric Antigen Receptor-Modified T Cells for In Vivo Studies in Syngeneic Tumor Models.

CAR-T cell therapy has emerged as a potent and effective tool in the immunotherapy of refractory cancers. However, challenges exist in their clinical application, necessitating extensive preclinical research to optimize their function. Various preclinical in vitro and in vivo models have been proposed for such purpose; among which immunocompetent mouse models serve as an invaluable tool in studying host immune interactions within a more realistic simulation of the tumor milieu. We hereby describe a standardized protocol for the generation of high-titer γ-retroviral vectors through transfection of the HEK293T packaging cell line. The virus-containing supernatant is further concentrated using an inhouse concentrator solution, titrated, and applied to mouse T cells purified via a convenient and rapid method by nylon-wool columns. Using the method presented here, we were able to achieve high titer γ-retrovirus and highly pure mouse T cells with desirable CAR transduction efficiency. The mouse CAR T cells produced through this protocol demonstrate favorable CAR expression and viability, thus making them suitable for further in vitro/in vivo assays. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Production of γ-retroviral vectors from retrovirus-backbone plasmids Basic Protocol 2: Concentration of γ-retrovirus-containing supernatants Basic Protocol 3: Titration of concentrated γ-retrovirus Basic Protocol 4: Isolation and activation of mouse T cells Basic Protocol 5: Transduction of activated mouse T cells, assessment of CAR expression, and expansion of CAR T cells for further in vitro/in vivo studies Support Protocol: Surface staining of cells for flow cytometric assessment of CAR expression.

Antiproliferative Effect of 7-Ketositosterol in Breast and Liver Cancer Cells: Possible Impact on Ceramide, Extracellular Signal-Regulated Kinases, and Nuclear Factor Kappa B Signaling Pathways.

Background: This study aimed to examine the effect of 7-Ketositosterol (7-KSS), on sphingomyelin/ceramide metabolites and apoptosis in human breast MCF-7 and human liver HepG2 cancer cells. Methods: Anti-proliferative effects of 7-KSS treatment were assessed at different concentrations and periods. Cell viability was assessed through MTT analysis, whereas the levels of sphingosine-1-phosphate (S1P), sphingomyelins (SMs), and ceramides (CERs) were measured using LC-MS/MS. Phosphorylated 44/42 ERK1/2 and NF-κB p65 (Ser536) protein levels were measured by Western blot analysis and immunofluorescence staining. Apoptosis was evaluated by TUNEL staining and flow cytometric assessment of annexin-V and propidium iodide (PI) labeling. Results: Treatment with 7-KSS significantly decreased cell survival and S1P, p-44/42 ERK1/2, and p-NF-κB p65 protein levels in cancer cells compared to controls. A substantial rise was detected in intracellular amounts of C16-C24 CERs and apoptosis in cancer cells incubated with 7-KSS. Conclusions: 7-KSS stimulated ceramide accumulation and apoptosis while decreasing cell proliferation via downregulating S1P, p-44/42 ERK1/2, and p-NF-κB p65 protein levels.

Utility of leukocyte-associated immunoglobulin-like receptor-1 (CD305) in flow cytometric detection of minimal bone marrow involvement by B-cell non-Hodgkin lymphoma.

Multicolor flow cytometry (MFC) is crucial in detecting occult or minimal bone marrow (BM) involvement by non-Hodgkin lymphomas (NHL), which may not be detected using trephine biopsy or imaging studies. Detection of low-level BM involvement can be challenging without definite immunophenotypic aberrancies. We studied the utility of CD305 in MFC detection of minimal BM involvement by B-NHL, especially in the absence of aberrancies by commonly used markers. The study included 1084 consecutive BM samples submitted for the staging of B-NHLs (excluding CLL) over two years. Samples were studied for morphological, immunophenotypic, and histopathological assessment. MFC studies were performed using 10-13 color MFC, including CD305-antibody (clone, DX26). Minimal BM involvement was defined with a cutoff of ≤10% lymphoma cells in viable cells on MFC assessment. Of 1084, 148 samples revealed overt morphological involvement by B-NHL and were excluded from analysis. BM samples of 172/936 patients were morphologically negative but revealed involvement using MFC independently. Corresponding trephine biopsy involvement was detected in only 79/172 (45.9%) patients. On MFC, 23/172 samples showed BM involvement with >10% lymphoma cells, and 149/172 (86.6%) samples revealed minimal involvement. In 54/149 (36.24%) samples, lymphoma cells were detected only with aberrant loss of CD305 expression. In 78 of the remaining 95 samples (82.1%), it provided an immunophenotypic aberrancy addition to other markers and supported the results. CD305 is a highly useful marker in the flow cytometric assessment of minimal BM involvement by B-NHL. MFC is a superior modality to trephine biopsy in detecting low-level BM involvement.

HER2 expression-independent antitumor effect of trastuzumab deruxtecan (T-DXd) on pediatric solid tumors.

e15016 Background: Treatment of pediatric solid tumors shows limited improvement even with intensification of conventional chemotherapy, suggesting novel approaches such as targeted therapies are needed. Trastuzumab Deruxtecan (T-DXd), a HER2-targeting antibody–drug conjugate, exhibits significant anti-cancer activity in breast cancers with a broad range of HER2 expression. T-DXd might be a promising agent for refractory or relapsed pediatric solid tumors, but its efficacy in pediatric tumors needs to be studied. Methods: Anti-cancer efficacy of T-DXd and its payload DXd were assessed in vitro by utilizing our in-house cancer cell line models. Cytotoxicity assays were performed for 60 pediatric cancer cell lines, including Neuroblastoma (NB) = 25, Ewing sarcoma / Ewing sarcoma family of tumors (EWS / EWSFT) = 17, Rhabdomyosarcoma (RMS) = 10, Others (Osteosarcoma, Brain tumor, Wilms tumor, Hepatoblastoma, and Malignant rhabdoid tumor (MRT) = 8, and 2 breast cancer cell lines expressing HER2 high or low (IHC score 2+ or 0) as positive or low control, respectively. We analyzed HER2 expression on the cell surface by flow cytometry and evaluated relative mean fluorescence intensity (MFI) values. Results: In the flow cytometric assessment, pediatric cancer cell lines showed smaller median MFI of 1.40 (0.67 - 2.71) compared with breast cancer control with HER2 high expression (33.77). The median MFI of each cell lines were 0.94 in NB, 1.76 in EWS / EWSFT, 1.42 in RMS, 1.52 in other pediatric cancers. Although low or no expression of HER2, certain inhibitory activities to the cell growth were observed for T-DXd against a part of NB, EWS, RMS and MRT cell lines, with the minimum IC50 values of 14.5 nM, 6.5 nM, 10.2 nM, 8.1 nM, respectively. In NB, EWS and RMS, a wide range of sensitivity to T-DXd were seen among different cell lines in the same disease. Most of cell lines showed high sensitivity to DXd (Median IC50 value: 0.90 nM [0.08 - 6.46 nM]), but, among them, cell lines with lower sensitivity to DXd tend to show less sensitivity to T-DXd. There was no clear correlation between sensitivity to T-DXd and HER2 expression among pediatric cancer cell lines, indicating that other mechanism such as intrinsic sensitivity to payload might affect antitumor activity of T-DXd. Conclusions: T-DXd exhibited antitumor efficacy against pediatric solid tumors in vitro irrespective of HER2 expression. Our results suggest that T-DXd might be an alternative therapy for pediatric solid tumor cases for whom conventional chemotherapies and other targeting therapies are ineffective. This study supports further investigation for T-DXd in this population.

Investigating the Effects of Dorema hyrcanum Root Extracts on Selective Induction of Programmed Cell Death in Glioblastoma, Ovarian Cancer and Breast Cancer Cell Lines.

Despite remarkable advances, cancer has remained the second cause of death, which shows that more potent novel compounds should be found. Ethnobotanical compounds have a long history of treating diseases, and several approved chemotherapeutic compounds were isolated from plants. The research aimed to evaluate the cytotoxic effects of Dorema hyrcanum root extract on ovarian, breast, and glioblastoma cells while examining its selectivity towards normal cells. Additionally, the study is directed to investigate cell death mechanisms, delineate modes of cell death, and explore intracellular ROS production. Cytotoxic effects of alcoholic, dichloromethane, and petroleum ether fractions of Dorema hyrcanum were investigated on cancer and normal cells by using MTT assay, and the concentration around IC50 values was used for flow cytometric assessment of apoptosis, evaluation of the expression of selected genes via RT-qPCR and production of ROS. Methanolic extract exhibited the highest cytotoxicity, impacting A2780CP and MDA-MB-231. All fractions showed comparable effects on U251 cells. Notably, extracts displayed higher IC50 values in normal HDF cells, indicating cancer cell specificity. Flow cytometry revealed induction of apoptosis and non-apoptotic death in all three cancer cell lines. QPCR results showed upregulation of related genes, with RIP3K prominently increased in U251 glioblastoma. The DCFH-DA assay demonstrated ROS induction by the PE fraction exclusively in A2780CP cells after 30 minutes and up to 24 hours. Dorema hyrcanum root extracts exhibited potent anti-tumor effects against all studied cell lines. The methanolic extract demonstrated the highest cytotoxicity, particularly against A2780CP and MDA-MB-231 cells. Importantly, all fractions displayed selectivity for cancer cells over normal HDF cells. Unique modes of action were observed, with the petroleum ether fraction inducing significant non-apoptotic cell death. These findings suggest promising therapeutic potential for Dorema hyrcanum in cancer treatment with subject to further mechanistic studies.

PD-BAT: A novel approach of pooling basophil donors for expansion of commercial laboratory testing of Chronic Spontaneous Urticaria

The type II autoimmune subtype of Chronic Spontaneous Urticaria (CSU) is characterized by the presence of IgG autoantibodies targeting IgE or the IgE high-affinity receptor (FcεRI) on mast cells and basophils. In evaluation of CSU patients, indirect basophil activation testing (BAT), has been utilized, involving the mixing of patient serum with heterologous peripheral blood donors, followed by flow cytometric assessment of basophil markers. However, the reliability of the indirect BAT results hinges on the quality of the donor basophils utilized. In this study, we introduce an innovative approach where multiple potential basophil donors undergo rigorous BAT characterization alongside control samples. By selecting and pooling donors with optimal performance, we significantly enhance the inter-assay reproducibility of the indirect BAT test.

Studying Adipose Endothelial Cell/Adipocyte Cross-Talk in Human Subcutaneous Adipose Tissue.

Microvascular endothelial cells (MVECs) have many critical roles, including control of vascular tone, regulation of thrombosis, and angiogenesis. Significant heterogeneity in endothelial cell (EC) genotype and phenotype depends on their vascular bed and host disease state. The ability to isolate MVECs from tissue-specific vascular beds and individual patient groups offers the opportunity to directly compare MVEC function in different disease states. Here, using subcutaneous adipose tissue (SAT) taken at the time of insertion of cardiac implantable electronic devices (CIED), we describe a method for the isolation of a pure population of functional human subcutaneous adipose tissue MVEC (hSATMVEC) and an experimental model of hSATMVEC-adipocyte cross-talk. hSATMVEC were isolated following enzymatic digestion of SAT by incubation with anti-CD31 antibody-coated magnetic beads and passage through magnetic columns. hSATMVEC were grown and passaged on gelatin-coated plates. Experiments used cells at passages 2-4. Cells maintained classic features of EC morphology until at least passage 5. Flow cytometric assessment showed 99.5% purity of isolated hSATMVEC, defined as CD31+/CD144+/CD45-. Isolated hSATMVEC from controls had a population doubling time of approximately 57 h, and active proliferation was confirmed using a cell proliferation imaging kit. Isolated hSATMVEC function was assessed using their response to insulin stimulation and angiogenic tube-forming potential. We then established an hSATMVEC-subcutaneous adipocyte co-culture model to study cellular cross-talk and demonstrated a downstream effect of hSATMVEC on adipocyte function. hSATMVEC can be isolated from SAT taken at the time of CIED insertion and are of sufficient purity to both experimentally phenotype and study hSATMVEC-adipocyte cross-talk.

Flow Cytometric Assessment of CD26-Positive Leukemic Stem Cells: A Rapid and Valuable Tool in the Diagnosis and Follow-Up of Chronic Myeloid Leukemia.

Context Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm. Recent studies have suggested that CD26-positive leukemic stem cells (LSCs) circulating in peripheral blood are specific for CML. Objective This study was undertaken to determine the proportion of CD26-positive LSCsat diagnosis and its change during tyrosine kinase inhibitor therapy. Design This prospective study was conducted on 43 cases of CML at diagnosis. For flow cytometry, peripheral blood cells were stained with CD45, CD34, CD38, CD3, and CD26. A sequential gating strategy with CD45/SSC (side scatter), CD34/SSC, and CD34/CD38 was applied to identify CD45+/34+/38- populations, from which CD26-positive stem cells were identified and compared with controls. Data analysis was done with Kaluza software. Results All patients diagnosed with CML were detected with CD26-positive LSCs. The median percentage of CD26-positive CML LSCs was 0.02 with a range of 0.001 to 1.77. None of the control samples showed CD26 positivity. The percentage and absolute count of CD26-positive CML LSCs were reduced after six months of tyrosine kinase therapy in patients with complete hematological remission. Conclusion Flow cytometric analysis of circulating CD26-positive CML LSCs is a non-invasive, rapid, and useful tool in the diagnosis and follow-up of CML.

Wiskott-Aldrich syndrome protein expression in female WAS carriers: A flow cytometry study from North India.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked inborn error of immunity characterized by microthrombocytopenia, infections, eczema, and increased predisposition to develop autoimmunity and malignancy. Flow cytometric assay for determining WAS protein (WASp) is a rapid and cost-effective tool for detecting patients. However, very few studies described WASp expression in female carriers. Most WAS carriers are clinically asymptomatic. Active screening of female family members helps identify female carriers, distinguish de novo mutations, and to select appropriate donor prior to curative stem cell transplantation. This study was undertaken to evaluate the diagnostic capability of flow cytometry-based WASp expression in peripheral blood cells to identify carriers and compare WASp expression in different blood cell lineages. Female patients, heterozygous for WAS gene, were enrolled in this study conducted at Pediatric Allergy Immunology Unit, Advanced Pediatric Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India. Flow cytometric assessment of WASp expression in lymphocytes, monocytes, and neutrophils was carried out and compared with healthy control and affected patients. The results were expressed in delta (Δ) median fluorescence intensity (MFI) as well as stain index (SI), which is the ratio of ΔMFI of patient and ΔMFI of control. Thirteen mothers and two sisters of genetically confirmed WAS patients were enrolled in the study. All enrolled females were clinically asymptomatic and did not have microthrombocytopenia. Low WASp expression (SI<1) was seen in lymphocytes and monocytes in 10 (66.6%) carriers. Females with variants in proximal exons (exons 1 and 2) were found to have lesser expression than those with distal (exons 3-12) variants. Flow cytometry is a rapid, easily available, cost-effective tool for WASp estimation. Lymphocytes followed by monocytes are the best cell lineages for WASp estimation in carrier females. However, genetic testing remains the gold standard, as carrier females with variants in distal exons may have normal WASp expression.

Concurrent Versus Sequential or No Triazole Anti-Fungal Therapy in Patients Undergoing 7+3 Plus Midostaurin Induction for FLT-3 Acute Myelogenous Leukemia

Background Midostaurin is a multikinase inhibitor approved for the treatment of adult patients with newly diagnosed FMS-like tyrosine kinase 3 (FLT3) mutated acute myeloid leukemia (AML) (Stone RM et al. NEJM 2017). Azole antifungal medications are commonly used in AML and are known to interact with anti-cancer drugs such as Midostaurin through the CYP3A pathway. This could result in an increase in midostaurin concentrations and toxicities, and lead to potential dose interruptions or modifications. However, the literature is scarce on outcomes in patients who are receiving an azole antifungal with intensive induction chemotherapy in combination with midostaurin (Sechaud R et al. Cancer Chemother Pharmacol 2022). In addition to the scarcity of literature, there are no midostaurin related dose modifications that are recommended with strong CYP3A inhibitors. The primary objective of this retrospective study was to compare induction efficacy and safety outcomes in patients receiving concurrent azole antifungal to patients receiving sequential or no azole antifungal therapy. Methods: From January 1, 2017, to January 30, 2023, we retrospectively reviewed all adult patients (18 or older) with newly diagnosed AML who received midostaurin in combination with cytarabine and an anthracycline (7+3). Concurrent azole therapy was defined as patients receiving an azole antifungal therapy with midostaurin for more than 70% of the midostaurin doses. Sequential azole therapy was defined as patients receiving azole antifungal therapy with midostaurin for less than 70% of the doses or no azole antifungal therapy with midostaurin therapy. Response outcome CR and CR without hematological recovery (CRi) were defined per standard International Working Group (IWG) AML response criteria. Minimal residual disease (MRD) assessment was done on post-induction bone marrow aspirate using multiparametric flow cytometric assessment. Adverse events were graded using NCI Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. We compared efficacy and safety outcomes in patients who received azole antifungals concurrently to those who did not receive an azole or received it sequentially to midostaurin for treatment of FLT3 AML. Mann-Whitney U test method was used to compare continuous variables between these two groups. Pearson Chi-square test or Fisher Exact test was used to compare categorical variables (count, rate or proportion) between these two groups. The choice of concurrent azole or sequential azole antifungal was determined by physician choice. Results: There were 40 patients treated with 7+3+midostaurin, 18 of whom received concurrent azole therapy, while 22 received sequential or no azole therapy. There were no significant differences in baseline characteristics (Table 1) except for more patients receiving isavuconazole (moderate CYP 3A4 inhibitor) in the concurrent group (50% vs 0%; p&amp;lt;0.01) and more micafungin in the sequential or no azole group (0% vs 72%; p&amp;lt;0.01). Overall CR/CRi rate with concurrent versus sequential or no azole was 72% (13/18) vs 77% (17/22), with no significant difference in median days to ANC recovery (27 vs 29; p=0.98), platelet recovery (28 vs 32 days; p=0.67), and non-hematologic grade 3 toxicities (22% and 45%; p=0.13), respectively. There were higher, but not significant, rates of midostaurin dose reductions (6% vs 0%; p=0.26) and holds (17% vs 14%; p=0.79) in the concurrent azole group. Conclusion: In conclusion, the addition of azole antifungal was found to be equally safe and effective in the treatment of newly diagnosed FTL3 AML. Dose modifications in midostaurin appeared not to be necessary with concurrent azole antifungal therapy. Further analysis based on a larger cohort is needed to confirm the outcomes and safety endpoints reported in the current study. Given the importance of azole anti-fungal therapy in the treatment of AML and specifically in induction therapy for AML (Cornely et al, NEJM 2007), dose modifications for this drug interaction should be studied in the future to help guide clinicians on how to appropriately dose these drugs.

Detection and Prevention of ADAR1p150-Induced Hematopoietic Stem and Progenitor Cell Aging

Introduction: Over the last decade, ADAR1p150 has been linked by our research team and others to malignant progenitor reprogramming and therapeutic resistance in a broad array of malignancies. However, ADAR1p150's role in accelerated hematopoietic stem and progenitor cell (HSPC) aging in response to inflammatory cytokines had not been clearly elucidated. Here, we investigate ADAR1 splice isoform switching and the ADAR1p150 inhibitory effects of Rebecsinib on human HSPC function in normal humanized aged normal bone marrow (aNBM) HSPC mouse models. Methods: Whole transcriptome RNA sequencing (RNA-seq) was utilized with splice isoform and editome analysis to detect ADAR1 splice isoform switching and adenosine to inosine RNA editing. Rebecsinib (17S-FD-895), a pre-IND drug candidate, has shown promising potential as an inhibitor of ADAR1p150-mediated RNA editing ( Crews, Ma...Jamieson. Cell Stem Cell 2023), which is an important therapeutic target in patients with myelofibrosis or acute myeloid leukemia that overexpress ADAR1p150 compared with ADAR1p110. Human CD34 + cells, isolated from aged normal bone marrow (aNBM) from patients undergoing elective hip replacement surgery, were transduced with a lentiviral ADAR1-nano-luciferase reporter and transplanted into NSG-SGM3 adult mice that secrete human SCF, IL-3, and GM-CSF cytokines that support normal hematopoiesis. After engraftment confirmation peripheral blood human CD45 flow cytometric assessment and IVIS 200 system imaging of ADAR1-nano-luc-GFP reporter expressing HSPC engraftment, the mice were randomly divided into vehicle-treated and Rebecsinib-treated groups (15mg/kg, twice a week for two weeks). Peripheral blood, bone marrow, and spleen were collected upon treatment completion for analysis. Results: By HSPC RNA-seq, we detected an imbalance between ADAR1p150 and ADAR1p110 expression together with increased RNA editing and splicing alterations using whole transcriptome RNA sequencing (RNA-seq) of aged compared with young bone marrow hematopoietic stem and progenitor cells (HSPCs). However, the functional relevance of ADAR1 splice isoform switching had not been evaluated in human-aged normal bone marrow HSPC xenograft (PDX) mouse models nor had this cytokine-induced HSPC aging been reversed. Flow cytometric analysis and immunohistochemistry staining revealed that Rebecsinib treatment at a dose of 10mg/kg, twice a week for two weeks, effectively spared normal human immune cells (CD3+, CD14+, and CD19+ cells). Remarkably, Rebecsinib treatment not only preserved Hematopoietic Stem (CD34+CD38-) cells and Progenitor (CD34+CD38+) cells in peripheral blood, bone marrow, and spleen but also promoted their expansion. These findings demonstrate the potential of Rebecsinib to enhance the retention of HSPC populations in the bone marrow niche. Conclusions: Our pre-clinical experiments utilizing RNA-seq, a novel ADAR1-nano-luciferase-GFP reporter, and aNBM PDX mouse models provide compelling evidence supporting the potential of Rebecsinib to restore the balance of ADAR1p150:p110 ratios and engraftment in humanized aNBM HSPC mouse models. These findings highlight Rebecsinib as a promising therapeutic candidate for targeting leukemia and myelofibrosis while preserving essential HSPC populations.

Single Center Retrospective Study of Midostaurin Plus Intensive Chemotherapy for Older Patients with Newly Diagnosed FLT-3 Mutated Acute Myelogenous Leukemia

Background: Mutations in FLT3 (FLT3m), either internal tandem duplication (ITD) or tyrosine kinase domain (TKD) are found in approximately 25% of AML patients. The current standard of care for eligible patients is induction chemotherapy with 7 + 3 regimen with the addition of multikinase inhibitor midostaurin, based on CALGB 10603 which enrolled patients up to 59 years of age (Stone et al; NEJM 2017). Quizartinib recently demonstrated improved overall survival (OS) compared to placebo when combined with standard 7+3 induction in patients up to 75 years of age, although the benefit in patients 60 and above was less clear (Erba et al; Lancet Oncol 2023). We sought to review the clinical outcomes among patients 60 years of age or greater at our institution for who received midostaurin with 7+3 for newly diagnosed (ND) FLT3m AML. Methods: We retrospectively reviewed 20 patients, 60 years of age or older who received midostaurin in combination with 7+3 (7+3+Mido) for the treatment of ND-FLT3m AML. Response criteria of CR (complete remission) and CR without hematological recovery (CRi) were defined per standard International Working Group (IWG) AML response criteria. The primary endpoint was defined as composite CR rate (cCR: defined as patients achieving CR +CRi). Minimal residual disease (MRD) assessment was done on post-induction bone marrow aspirate using multiparametric flow cytometric assessment. The secondary endpoints were OS, leukemia-free survival (LFS) among patients with CR/Cri and proportion of patients who underwent subsequent allogeneic hematopoietic cell transplant (alloHCT). Results: Patients' demographic, cytogenetic and molecular features are summarized in Table 1, briefly, the median age was 64 (range 61-75), males (n=12, 60%), de novo AML (n=19, 95%), FLT3 ITD (n=13, 65%), FLT3 TKD (n=7, 35%). The most common consolidation regimen was high dose cytarabine (HiDAC) in combination with midostaurin (n=5, 25%). Grade 3 or higher hematologic toxicity was uniformly seen and the most common grade 3 or higher non-hematologic toxicities were neutropenic fever (19/20; 95%), cardiac disorders (3/20; 15%), and diarrhea (3/20; 15%). Dose reductions/interruption of midostaurin was required in 35% patients (n=7) and one patient died due to induction related mortality. 7+3+Mido yielded an overall response rate of 90% (18/20), with cCR noted in 75% (15/20) and MLFS seen in 15% (3/20) patients. MRD negative remission was documented in 40% (6/15) patients treated (table 2). The median follow up for the entire cohort was 9.3 months and overall survival at 6 months was 70% (14/20). The majority of patients, 70% (14/20) subsequently underwent alloHCT from matched or haploidentical donor. Reduced intensity conditioning (n=12/14; 86%) and GVHD prophylaxis with tacrolimus/ sirolimus prophylaxis (n=8; 57%) was commonly used in patients undergoing alloHCT. Six patients did not proceed to alloHCT due to death (n=4, one each due to sepsis, disease progression, infection, or intracranial bleed), comorbid conditions (n=1) or short follow up. The median OS for non HCT group was 2.3 months (range: 0.6-6.5). Detailed HCT outcomes data was available subset of patients at last data cut off (9/14; 65%). The Median age of patients undergoing HCT was 65 years (range: 62-76). The median KPS and HCT-CI for these patients was 90% (range :80-90%) and 1.5(range: 0-5) respectively. The majority of patients underwent alloHCT in CR-1(90%), all using PBSC graft from donor. The median duration of follow-up from transplant to last contact or death in the nine evaluable patients was 12.1 months. Median OS and leukemia free survival was not reached and 1-year GRFS was 50% (range:14-79%). Five patients (36%) patients received post-transplant FLT3 maintenance with the most common agents being midostaurin (n=2) and gilteritinib (n=2). Conclusion: The addition of midostaurin to intensive 7+3 chemotherapy induction for ND FLT3m AML is feasible and well tolerated in older AML patients. The combination results in high remission rates and the majority of patients are able to proceed to alloHCT.