(WASHINGTON) – Welcome to “This Week in Blood,” a weekly snapshot of the hottest studies from each week’s issue of Blood, the official journal of the American Society of Hematology (ASH), hand-picked by Blood Editor-in-Chief Bob Löwenberg, MD, and Deputy Editor Nancy Berliner, MD. If you would like a PDF copy of any of the manuscripts highlighted below or would like to request an interview with the author, please email firstname.lastname@example.org.
Fibrocytes represent a novel MDSC subset circulating in patients with metastatic cancer, Zhang et al.
Myeloid-derived suppressor cells (MDSCs) are a distinct subset of marrow-derived immature leukocytes that have been observed to expand in the presence of cancer and help tumors evade immunologic attack. In this week’s issue of Blood, Zhang and colleagues add to the growing literature that describes altered cellular phenotypes in the cancer microenvironment. They demonstrate that fibrocytes, hematopoietic stem cell-derived fibroblast precursors that are antigen-presenting cells in non-tumor-bearing hosts, also expand in the presence of metastatic cancer and that these too have immunosuppressive activity, inducing T cell proliferation and augmenting immune activity. Here, the authors demonstrate that, in contrast, these cells suppress T cell proliferation in the presence of cancer. These studies identify a new subset of MDSCs modified by the tumor microenvironment that may contribute to tumor growth and metastasis.
Risk profile and clinical outcome of symptomatic subsegmental acute pulmonary embolism, den Exter et al.
The use of high-resolution computed tomography (CT) scans to detect pulmonary embolism (PE) has led to a markedly increased diagnosis of small subsegmental PEs, causing speculation that the markedly increased sensitivity of the scans might be contributing to overdiagnosis and overtreatment of patients. In this week’s issue of Blood, den Exter and colleagues address this question in a review of more than 3,700 cases of suspected PE evaluated by high-resolution CT scans. They demonstrate that patients with subsegmental PE have comparable risk and outcomes as those with more proximal PE. This suggests that all patients with PE, regardless of the location of the clot, should be anticoagulated.
A case of paroxysmal nocturnal hemoglobinuria caused by a germline mutation and a somatic mutation in PIGT, Krawitz et al.
Paroxysmal nocturnal hemoglobinuria (PNH) is attributable to an acquired mutation in the PIGA gene. Since the gene is on the X chromosome, a single mutation is sufficient to render a null phenotype, leading to loss of GPI-anchored proteins. In this week’s issue of Blood, Kravitz and colleagues analyze a rare patient with PNH lacking a PIGA mutation. Using deep sequencing of all genes known to contribute to the synthesis of GPI-anchors, investigators confirm that the patient had a constitutional heterozygous mutation in the PIGT gene, and that a gene conversion event in a hematopoietic stem cell resulted in a clonal population of PIGT-null hematopoietic cells, causing PNH. These results raise provocative questions: The patient’s long history of urticaria and a concomitant diagnosis of inflammatory bowel disease suggests that patients with heterozygous mutations in genes in this pathway may have other clinical effects that remain to be elucidated. Furthermore, while homozygous PIGT loss has been reported in four children who had multiple congenital malformations and intellectual disability, it has not been reported in patients with PNH. These results suggest that PNH may arise from lesions in genes other than PIGA and call for additional research regarding the role of other genes in this pathway in additional disease phenotypes.
Blood (www.bloodjournal.org), the most cited peer-reviewed publication in the field of hematology, is available weekly in print and online. Blood is the official journal of the American Society of Hematology (ASH) (www.hematology.org), the world’s largest professional society concerned with the causes and treatment of blood disorders.
ASH’s mission is to further the understanding, diagnosis, treatment, and prevention of disorders affecting blood, bone marrow, and the immunologic, hemostatic, and vascular systems by promoting research, clinical care, education, training, and advocacy in hematology.
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