Elin Rodger

Augmented mobilization and collection of CD34+ hematopoietic cells from normal human volunteers stimulated with granulocyte-colony-stimulating factor by single-dose administration of AMD3100, a CXCR4 antagonist.

BACKGROUND: AMD3100, a selective antagonist of CXCR4, rapidly mobilizes CD34+ hematopoietic progenitor cells (HPCs) from marrow to peripheral blood with minimal side effects.

Neutrophil transfusions : kinetics and functions of neutrophils mobilized with granulocyte-colony-stimulating factor and dexamethasone

BACKGROUND: The collection of adequate numbers of neutrophils (polymorphonuclear leukocytes, PMNs) from normal donors has long hampered the development of neutrophil transfusion therapy. The stimulation of donors with granulocyte‐colony‐stimulating factor (G‐ CSF) plus dexamethasone is a promising way of improving PMN collections.

Prevalence of mutations in ELANE, GFI1, HAX1, SBDS, WAS and G6PC3 in patients with severe congenital neutropenia

Severe congenital neutropenia (SCN) is a genetically heterogeneous syndrome associated with mutations of ELANE (ELA2), HAX1, GFI1, WAS, CSF3R or G6PC3. We investigated the prevalence of mutations of ELANE in a cohort of 162 SCN patients for whom blood or bone marrow samples were submitted to the North American Severe Chronic Neutropenia Tissue Repository. Mutations of ELANE were found in 90 of 162 patients (55·6%). Subsequently, we conducted an analysis of a subset of 73 of these cases utilising a high throughput sequencing approach to determine the prevalence of other mutations associated with SCN. Among the 73 patients, mutations of ELANE were detected in 28. In the remaining 45 patients with wild type ELANE alleles, five patients had mutations: GFI1 (1), SBDS (1), WAS (1) and G6PC3 (2); no mutations of HAX1 were detected. In approximately 40% of our cases, the genetic basis of SCN remains unknown. These data suggest that for genetic diagnosis of SCN, ELANE genotyping should first be performed. In patients without ELANE mutations, other known SCN‐associated gene mutations will be found rarely and genotyping can be guided by the clinical features of each patient.

Leukocytosis and Mobilization of CD34+ Hematopoietic Progenitor Cells by AMD3100, a CXCR4 Antagonist

Stromal cell-derived factor-1 (SDF-1/CXCL12) plays a key regulatory role in the trafficking of hematopoietic cells. AMD3100 is a specific antagonist of the binding of SDF-1 to its receptor, CXCR4. This phase I study assessed the hematological effects, pharmacokinetics, and safety of administration of AMD3100 to 32 healthy volunteers, including its ability to mobilize CD34+ hematopoietic progenitor cells. A generalized leukocytosis occurred after a single subcutaneous injection of AMD3100 (80 microg/kg) resulting in a maximum white blood cell count of 19.49 +/- 1.27 x 103/microL (mean +/- SEM) at 6 hours. No changes were observed in erythrocyte or platelet counts. Circulating CD34+ cells increased 5-fold after administration of AMD3100 at 80 mug/kg and 15.5-fold in response to AMD3100 at 240 mug/kg, both at 9 hours after injection. Myeloid progenitor cells-colony forming unit granulocytemacrophage (CFU-GM); CFU-granulocyte, eosinophil, monocyte, megakaryocyte (CFU-GEMM); and burst forming units-erythroid showed similar increases in mobilization to the blood with increasing doses of AMD3100. The mobilized cells were in a slow or noncycling state as determined by in vitro high specific activity of 3H-thymidine. Pharmacokinetic studies showed a near linear increase in peak drug levels with increasing doses and nearly complete elimination of the drug by 24 hours. AMD3100 was well tolerated with only mild and transient toxicities (injection site erythema, headache, paresthesia, nausea, and abdominal distension) observed. These observations suggest that AMD3100 may be a clinically useful agent for hematopoietic progenitor cell mobilization.

Neutrophil elastase mutations and risk of leukaemia in severe congenital neutropenia.

Severe congenital neutropenia (SCN) is a heterogeneous bone marrow failure syndrome predisposing to myelodysplastic syndrome and acute myeloid leukaemia (MDS/AML). We studied 82 North American and Australian SCN patients enrolled in the Severe Chronic Neutropenia International Registry who were on long‐term treatment with granulocyte colony‐stimulating factor and for whom the neutrophil elastase (ELA2) gene was sequenced. There was no significant difference in the risk of MDS/AML in patients with mutant versus wild‐type ELA2: the respective cumulative incidences at 15 years were 36% and 25% (P = 0·96). Patients with either mutant or wild‐type ELA2 should be followed closely for leukaemic transformation.

Combined administration of G–CSF and dexamethasone for the mobilization of granulocytes in normal donors: optimization of dosing

BACKGROUND: The clinical utility of neutrophil (polymorphonuclear leukocyte, PMN) transfusion therapy has been compromised, in part, by the inability to obtain sufficient quantities of functional neutrophils from donors. Mobilization of PMNs in the peripheral blood of normal volunteers has been shown to be superior when G–CSF is administered in conjunction with dexamethasone to that when either agent is administered alone. The current study was conducted to determine the optimal dosages of G–CSF and dexamethasone to be administered to donors in a granulocyte transfusion program.

The diversity of mutations and clinical outcomes for ELANE-associated neutropenia.

Purpose of reviewMutations in the gene for neutrophil elastase, ELANE, cause cyclic neutropenia (CyN) and severe congenital neutropenia (SCN). This study summarized data from the Severe Chronic Neutropenia International Registry (SCNIR) on genotype–phenotype relationships of ELANE mutations to important clinical outcomes. We also summarize findings for ELANE mutations not observed in SCNIR patients. Recent findingsThere were 307 SCNIR patients with 104 distinctive ELANE mutations who were followed longitudinally for up to 27 years. The ELANE mutations were diverse; there were 65 single amino acid substitutions; 61 of these mutations (94%) were ‘probably’ or ‘possibly damaging’ by PolyPhen-2 analysis, and one of the ‘benign’ mutations was associated with two cases of acute myeloid leukemia (AML). All frame-shift mutations (19/19) were associated with the SCN. The pattern of mutations in the SCN versus CyN was significantly different (P < 10–4), but some mutations were observed in both groups (overlapping mutations). The cumulative incidence of severe adverse events, that is, myelodysplasia, AML, stem cell transplantation, or deaths was significantly greater for patients with SCN versus those with CyN or overlapping mutations. Specific mutations (i.e. G214R or C151Y) had a high risk for evolution to AML. SummarySequencing is useful for predicting outcomes of ELANE-associated neutropenia.

Canine cyclic haematopoiesis: the effect of endotoxin on erythropoiesis

We have examined the effects of chronic endotoxin treatment on erythropoiesis in six grey collies with cyclic haematopoiesis. Blood reticulocytes, bone marrow erythroid colony (EC) forming cells, serum iron and erythropoietin (ESF) values showed regular periodic fluctuations in untreated grey collies. Daily endotoxin injections eliminated the cyclic fluctuations of reticulocytes and EC. The mean serum iron values were increased and recurrent hypoferraemia eliminated, while the mean serum ESF values were reduced. The cyclic fluctuations of serum ESF values were no longer apparent in the endotoxin treated grey collies. Tritiated thymidine suicide of the marrow EC forming cells failed to show cyclic changes either in untreated or endotoxin treated dogs. The ESF sensitivity of EC in the grey collie was unchanged during endotoxin treatment and was not different from normal dogs. Endotoxin appears to alter periodic erythropoiesis by stabilizing the flux of cells into the committed erythroid precursor cell pool from a more primitive stem cell compartment.