M. L. Heltzer

The Children's Hospital of Philadelphia, Filadelfia, Pennsylvania, United States

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Publications (12)

  • Michael D Keller · Jaya Ganesh · Meredith Heltzer · [...] · Jordan S Orange
    [Show abstract] [Hide abstract] ABSTRACT: Folate and vitamin B(12) metabolism are essential for de novo purine synthesis, and several defects in these pathways have been associated with immunodeficiency. Here we describe the occurrence of severe combined immunodeficiency (SCID) with megaloblastic anemia, leukopenia, atypical hemolytic uremic syndrome, and neurologic abnormalities in which hydroxocobalamin and folate therapy provided partial immune reconstitution. Whole exome sequencing identified compound heterozygous mutations in the MTHFD1 gene, which encodes a trifunctional protein essential for processing of single-carbon folate derivatives. We now report the immunologic details of this novel genetic cause of SCID and the response to targeted metabolic supplementation therapies. This finding expands the known metabolic causes of SCID and presents an important diagnostic consideration given the positive impact of therapy.
    Article · Jan 2013 · PEDIATRICS
  • Source
    Meredith L Heltzer · Susan E Coffin · Kelly Maurer · [...] · Kathleen E Sullivan
    [Show abstract] [Hide abstract] ABSTRACT: Among previously healthy children with severe influenza, the mechanisms leading to increased pathology are not understood. We hypothesized that children with severe influenza would have high levels of circulating cytokines. To examine this, we recruited patients with severe influenza and examined plasma cytokine levels as well as the ability of peripheral blood cells to respond to stimuli. Ten patients with severe influenza were enrolled during the 2005-2007 influenza seasons. We evaluated plasma cytokine levels, circulating NK cells, and responses to TLR ligands during the illness. We compared these patients with five patients with moderate influenza, six patients with respiratory syncytial virus (RSV), and 24 noninfected controls. Patients with influenza showed depressed responses to TLR ligands when compared with RSV patients and healthy controls (P<0.05). These normalized when retested during a convalescent phase. Plasma levels of IL-6, IL-12, and IFN- were elevated in influenza patients compared with controls (P<0.05). A compromised ability to produce TNF- was reproduced by in vitro infection, and the magnitude of the effect correlated with the multiplicity of infection and induction of IFN regulatory factor 4 expression. Aberrant, systemic, innate responses to TLR ligands during influenza infection may be a consequence of specific viral attributes such as a high inoculum or rapid replication and may underlie the known susceptibility of influenza-infected patients to secondary bacterial infections.
    Full-text available · Article · Mar 2009 · Journal of leukocyte biology
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    M.M. Suhoski · E.E. Perez · M.L. Heltzer · [...] · J.S. Orange
    [Show abstract] [Hide abstract] ABSTRACT: Monosomy 1p36 is a subtelomeric deletion syndrome associated with congenital anomalies presumably due to haploinsufficiency of multiple genes. Although immunodeficiency has not been reported, genes encoding costimulatory molecules of the TNF receptor superfamily (TNFRSF) are within 1p36 and may be affected. In one patient with monosomy 1p36, comparative genome hybridization and fluorescence in- situ hybridization confirmed that TNFRSF member OX40 was included within the subtelomeric deletion. T cells from this patient had decreased OX40 expression after stimulation. Specific, ex vivo T cell activation through OX40 revealed enhanced proliferation, and reduced viability of patient CD4+ T cells, providing evidence for the association of monosomy 1p36 with reduced OX40 expression, and decreased OX40-induced T cell survival. These results support a role for OX40 in human immunity, and calls attention to the potential for haploinsufficiency deletions of TNFRSF costimulatory molecules in monosomy 1p36.
    Full-text available · Article · Sep 2008 · Clinical Immunology
  • Meredith Lee Heltzer · Michele Paessler · Leslie Raffini · [...] · Elena Elizabeth Perez
    Article · Nov 2007 · Journal of Allergy and Clinical Immunology
  • Meredith Lee Heltzer · John K Choi · Hans D Ochs · [...] · Linda M Ernst
    [Show abstract] [Hide abstract] ABSTRACT: IPEX syndrome is a rare, inherited condition characterized by immune dysfunction, polyendocrinopathy, enteropathy, and X-linked recessive inheritance. Patients typically present in infancy with severe diarrhea and failure to thrive. Most children die by 1 year of age without therapy. The diagnosis is established by genetic analysis, which often takes several weeks to complete and can sometimes delay crucial immunosuppressive treatment. We attempted to develop a screening tool that allows rapid identification of patients with IPEX syndrome using immunocytochemical staining of FOXP3+ cells in bowel biopsies. We found that 2 patients with classic IPEX syndrome due to protein-truncating mutations in FOXP3 had markedly decreased staining of FOXP3+ T cells in the lamina propria and lymphoid aggregates. One patient with a mild, late-onset presentation and a missense mutation in FOXP3 had intact staining of FOXP3+ cells. This screening test provides a valuable tool for diagnosing IPEX syndrome in extremely ill patients who may not tolerate a delay in therapeutic intervention.
    Article · Mar 2007 · Pediatric and Developmental Pathology
  • M. L. Heltzer · J. P. Franciosi · M. Shuker · [...] · J. M. Spergel
    Article · Jan 2007 · Journal of Allergy and Clinical Immunology
  • M. L. Heltzer · J. S. Orange
    Article · Feb 2006 · Journal of Allergy and Clinical Immunology
  • ML Heltzer · LM Ernst · TR Torgerson · [...] · KE Sullivan
    Conference Paper · Sep 2005
  • Conference Paper · Sep 2005
  • M Heltzer · M Paessler · N Bunin · [...] · E Perez
    Conference Paper · Sep 2005
  • M. L. Heltzer · K. E. Sullivan
    Article · Feb 2005 · Journal of Allergy and Clinical Immunology
  • Meredith Heltzer · Abbas F Jawad · Julie Rae · [...] · Kathleen E Sullivan
    [Show abstract] [Hide abstract] ABSTRACT: Chronic granulomatous disease is a neutrophil disorder in which phagocytic cells fail to produce a respiratory burst. Five genetic types of chronic granulomatous disease have been described and in each case the clinical manifestations relate to the inability to effectively kill catalase-positive organisms. It is classically described as a pure disorder of intracellular killing, with preservation of other aspects of phagocytic function such as migration and phagocytosis and normal function of nonmyeloid cells. This article describes a heretofore unrecognized feature of chronic granulomatous disease. Fifty-three patients with chronic granulomatous disease and 42 age-matched controls were studied by flow cytometry. Total T cell numbers and CD4 and CD8 T cell numbers were compared between patients and controls. Patients with chronic granulomatous disease had diminished T cell numbers compared to controls after 3 years of age. The difference increased with age. It is not known whether diminished T cell numbers influence the susceptibility to infections in these patients, but T cell effects could represent a significant cofactor for infection.
    Article · Jan 2003 · Clinical Immunology