Hematogones in the Peripheral Blood of a 51/2-Month-Old Boy with Cyclic Neutropenia Due to Heterozygous, Novel ELANE Gene Mutation p.Q97P, c.290 A>C
PEDIATRIC AND DEVELOPMENTAL PATHOLOGY
Authors: Juranovic, Tajana; O'Suoji, Chibuzo C.; Sivakumaran, Theru A.; Zhang, Kejian; Estallila, Oscar C.; Jelic, Tomislav M.
Abstract
We have identified a novel point mutation in the ELANE gene of a 5.5-month-old boy with severe cyclic neutropenia, and we are reporting for the first time, to our knowledge, the presence of hematogones in the peripheral blood of an infant. The novel point mutation occurred at base number 290 in codon 97, where adenine was replaced with cytosine. The mutation caused the replacement of amino acid glutamine with amino acid proline in the activation domain of the elastase 2 enzyme. The heterozygous mutation generated severe cyclic neutropenia, granulocytic maturation arrest, an increased number of hematogones (26% of marrow cells) in the bone marrow, an absence of neutrophils, and the presence of stage 3 (mature) hematogones in the peripheral blood. The percentage of hematogones in the peripheral blood was inversely proportional to the absolute number of neutrophils. Leukemic number of blast-like cells (hematogones) in the bone marrow, blast-like cells in the peripheral blood, marked neutropenia, and the arrest of granulopoiesis might suggest an acute leukemia. However, the finding of characteristic flow cytometric features of hematogones should help to avoid a wrong diagnosis.
Murine lupus is neutrophil elastase-independent in the MRL.Fas(lpr) model
PLOS ONE
Authors: Gordon, Rachael A.; Tilstra, Jeremy S.; Marinov, Anthony; Nickerson, Kevin M.; Bastacky, Sheldon, I; Shlomchik, Mark J.
Abstract
Loss of tolerance to nuclear antigens and multisystem tissue destruction is a hallmark of systemic lupus erythematosus (SLE). Although the source of autoantigen in lupus remains elusive, a compelling hypothetical source is dead cell debris that drives autoimmune activation. Prior reports suggest that neutrophil extracellular traps (NETs) and their associated death pathway, NETosis, are sources of autoantigen in SLE. However, others and we have shown that inhibition of NETs by targeting the NADPH oxidase complex and peptidylarginine deiminase 4 (PADI4) did not ameliorate disease in spontaneous murine models of SLE. Furthermore, myeloperoxidase and PADI4 deletion did not inhibit induced lupus. Since NET formation may occur independently of any one mediator, to address this controversy, we genetically deleted an additional important mediator of NETs and neutrophil effector function, neutrophil elastase (ELANE), in the MRL.Fas(lpr) model of SLE. ELANE deficiency, and by extension ELANE-dependent NETs, had no effect on SLE nephritis, dermatitis, antiself response, or immune composition in MRL.Fas(lpr) mice. Taken together with prior data from our group and others, these data further challenge the paradigm that NETs and neutrophils are pathogenic in SLE.