Publications by authors named "Michael J Clemente"

This "Best Practices in User Consultation" article is the result of a 2022 International Society for the Advancement of Cytometry (ISAC) membership survey that collected valuable insights from the shared research laboratory (SRL) community and of a group discussion at the CYTO 2022 workshop of the same name. One key takeaway is the importance of initiating a consultation at the outset of a flow cytometry project, particularly for trainees. This approach enables the improvement and standardization of every step, from planning experiments to interpreting data.

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Introduction: Natural antibody (NAb) derived from CD5+ B-1 cells maintains tissue homeostasis, controls inflammation, aids in establishing long-term protective responses against pathogens, and provides immediate protection from infection. CD5+ B-1 cell NAbs recognize evolutionarily fixed epitopes, such as phosphatidylcholine (PtC), found on bacteria and senescent red blood cells. Anti-PtC antibodies are essential in protection against bacterial sepsis.

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Natural Abs are primarily produced by B-1 cells and are essential for protection against The incidence and mortality rate for pneumococcal infection increases dramatically after age 65, disproportionately affecting males in both human and murine systems. To date, there is a significant gap in our understanding of the relationship among sex, aging, natural IgM efficacy, and the natural IgM repertoire. Our investigation demonstrates that the protective capacity of serum IgM against pneumococcal infection is maintained in IgM obtained from aged female mice but absent in IgM from aged male mice.

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T large granular lymphocyte leukemia (T-LGLL) is a clonal lymphoproliferative disorder that can arise in the context of pathologic or physiologic cytotoxic T-cell (CTL) responses. mutations are often absent in typical T-LGLL, suggesting that in a significant fraction of patients, antigen-driven expansion alone can maintain LGL clone persistence. We set out to determine the relationship between activating hits and CTL clonal selection at presentation and in response to therapy.

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Large granular lymphocytic leukemia (LGLL) represents a clonal/oligoclonal lymphoproliferation of cytotoxic T and natural killer cells often associated with STAT3 mutations. When symptomatic, due to mostly anemia and neutropenia, therapy choices are often empirically-based, because only few clinical trials and systematic studies have been performed. Incorporating new molecular and flow cytometry parameters, we identified 204 patients fulfilling uniform criteria for LGLL diagnoses and analyzed clinical course with median follow-up of 36 months, including responses to treatments.

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Myelodysplastic syndromes are typically diseases of older adults. Patients in whom the onset is early may have distinct molecular and clinical features or reflect a demographic continuum. The identification of differences between "early onset" patients and those diagnosed at a traditional age has the potential to advance understanding of the pathogenesis of myelodysplasia and may lead to formation of distinct morphological subcategories.

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Background: Deletion of chromosome 5q (del(5q)) is the most common karyotypic abnormality in myeloid neoplasms.

Materials And Methods: To define the pathogenic molecular features associated with del(5q), next-generation sequencing was applied to 133 patients with myeloid neoplasms (MDS; N = 69, MDS/MPN; N = 5, sAML; N = 29, pAML; N = 30) with del(5q) as a sole abnormally or a part of complex karyotype and results were compared to molecular features of patients diploid for chr5.

Findings: A number of 5q genes with haploinsufficient expression and/or recurrent somatic mutations were identified; for these genes, CSNK1A1 and G3BP1 within the commonly deleted 5q region and DDX41 within a commonly retained region were most commonly affected by somatic mutations.

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Background: In patients with acquired aplastic anemia, destruction of hematopoietic cells by the immune system leads to pancytopenia. Patients have a response to immunosuppressive therapy, but myelodysplastic syndromes and acute myeloid leukemia develop in about 15% of the patients, usually many months to years after the diagnosis of aplastic anemia.

Methods: We performed next-generation sequencing and array-based karyotyping using 668 blood samples obtained from 439 patients with aplastic anemia.

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Next generation sequencing technologies have provided insights into the molecular heterogeneity of various myeloid neoplasms, revealing previously unknown somatic genetic events. In our cohort of 1444 cases analyzed by next generation sequencing, somatic mutations in the gene BRCA1-BRCA2-containing complex 3 (BRCC3) were identified in 28 cases (1.9%).

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T-cell large granular lymphocytic leukemia and chronic lymphoproliferative disorder of natural killer cells are intriguing entities between benign and malignant lymphoproliferation. The molecular pathogenesis has partly been uncovered by the recent discovery of somatic activating STAT3 and STAT5b mutations. Here we show that 43% (75/174) of patients with T-cell large granular lymphocytic leukemia and 18% (7/39) with chronic lymphoproliferative disorder of natural killer cells harbor STAT3 mutations when analyzed by quantitative deep amplicon sequencing.

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Paroxysmal nocturnal hemoglobinuria (PNH) is a nonmalignant clonal disease of hematopoietic stem cells that is associated with hemolysis, marrow failure, and thrombophilia. PNH has been considered a monogenic disease that results from somatic mutations in the gene encoding PIGA, which is required for biosynthesis of glycosylphosphatidylinisotol-anchored (GPI-anchored) proteins. The loss of certain GPI-anchored proteins is hypothesized to provide the mutant clone with an extrinsic growth advantage, but some features of PNH argue that there are intrinsic drivers of clonal expansion.

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Flow cytometry-based analysis of T-cell receptor (TCR) repertoires is an essential tool for the detection of clonal T-cell expansions in physiologic and pathologic conditions. Individual T-cell subsets can be investigated based on their surface properties. The aims of our study were to provide reference values for various disease settings and delineate the contribution of individual TCR repertoires to the human T-cell differentiation pathway.

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New massively parallel sequencing technology enables, through deep sequencing of rearranged T-cell receptor (TCR) Vβ complementarity-determining region 3 (CDR3) regions, a previously inaccessible level of TCR repertoire analysis. The CDR3 repertoire diversity reflects clonal composition, the potential antigenic recognition spectrum, and the quantity of available T-cell responses. In this context, T-large granular lymphocyte (T-LGL) leukemia is a chronic clonal lymphoproliferation of cytotoxic T cells often associated with autoimmune diseases and various cytopenias.

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Large granular lymphocyte leukemia (LGL) is often associated with immune cytopenias and can cooccur in the context of aplastic anemia (AA) and myelodysplastic syndromes (MDS). We took advantage of the recent description of signal transducer and activator of transcription 3 (STAT3) mutations in LGL clonal expansions to test, using sensitive methods, for the presence of these mutations in a large cohort of 367 MDS and 140 AA cases. STAT3 clones can be found not only in known LGL concomitant cases, but in a small proportion of unsuspected ones (7% AA and 2.

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Large granular lymphocytic (LGL) leukemia is characterized by clonal expansion of cytotoxic T cells or natural killer cells. Recently, somatic mutations in the signal transducer and activator of transcription 3 (STAT3) gene were discovered in 28% to 40% of LGL leukemia patients. By exome and transcriptome sequencing of 2 STAT3 mutation-negative LGL leukemia patients, we identified a recurrent, somatic missense mutation (Y665F) in the Src-like homology 2 domain of the STAT5b gene.

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Chronic lymphoproliferative disorders of natural killer cells (CLPD-NKs) and T-cell large granular lymphocytic leukemias (T-LGLs) are clonal lymphoproliferations arising from either natural killer cells or cytotoxic T lymphocytes (CTLs). We have investigated for distribution and functional significance of mutations in 50 CLPD-NKs and 120 T-LGL patients by direct sequencing, allele-specific PCR, and microarray analysis. STAT3 gene mutations are present in both T and NK diseases: approximately one-third of patients with each type of disorder convey these mutations.

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Background: T-cell large granular lymphocytic leukemia is a rare lymphoproliferative disorder characterized by the expansion of clonal CD3+CD8+ cytotoxic T lymphocytes (CTLs) and often associated with autoimmune disorders and immune-mediated cytopenias.

Methods: We used next-generation exome sequencing to identify somatic mutations in CTLs from an index patient with large granular lymphocytic leukemia. Targeted resequencing was performed in a well-characterized cohort of 76 patients with this disorder, characterized by clonal T-cell-receptor rearrangements and increased numbers of large granular lymphocytes.

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Large granular lymphocyte (LGL) leukemia is characterized by clonal expansion of antigen-activated cytotoxic T cells (CTL). Patients frequently exhibit seroreactivity against a human T-cell leukemia virus (HTLV) epitope, BA21. Aplastic anemia, paroxysmal nocturnal hemoglobinuria and myelodysplastic syndrome are bone marrow failure diseases that can also be associated with similar aberrant CTL activation (LGL-BMF).

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T-cell large granular lymphocyte leukemia (T-LGLL) is characterized by chronic lymphoproliferation of cytotoxic T lymphocytes (CTLs) and is associated with lineage-restricted cytopenias. Introduction of T-cell receptor (TCR) variable β-chain (Vβ) monoclonal antibodies has facilitated identification and enumeration of clonal CTLs by flow cytometry. A highly skewed TCR Vβ repertoire identified by flow cytometry is strongly associated with monoclonal CDR3 regions by quantitative sequencing and positive TCRγ rearrangement assays.

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Background: Large granular lymphocyte leukemia is a semi-autonomous clonal proliferation of cytotoxic T cells accompanied by immune cytopenias and various autoimmune conditions. Due to the rarity of this disease and its association with autoimmune diseases, a theoretical germline or somatic mutation might have significant penetrance, thus enabling detection, even from samples of suboptimal size, through genome-wide association studies.

Design And Methods: To investigate a non-mendelian genetic predisposition to large granular lymphocyte leukemia, we used a step-wise method for gene discovery.

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Background: T-cell large granular lymphocytic leukemia is a clonal proliferation of cytotoxic T-lymphocytes which often results in severe cytopenia. Current treatment options favor chronic immunosuppression. Alemtuzumab, a humanized monoclonal antibody against glycophosphatidylinositol-anchored CD52, is approved for patients refractory to therapy in other lymphoid malignancies.

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Final crossmatch testing is routinely used to assess the risk of antibody-mediated graft injury/rejection post-transplant. Analogously, we postulated that quantitative measurements of anti-donor effector/memory T cells pre-transplant would independently assess post-transplant risk. To address this hypothesis, we determined the frequencies of pre-transplant, donor-specific interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spots (ELISPOTs) and correlated the results with post-transplant outcomes in 37 African American recipients of deceased donor kidney transplants treated with tacrolimus- and sirolimus-based immunosuppression.

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