Lindsay Dunlop

A Novel Cobra Venom Metalloproteinase, Mocarhagin, Cleaves a 10-Amino Acid Peptide from the Mature N Terminus of P-selectin Glycoprotein Ligand Receptor, PSGL-1, and Abolishes P-selectin Binding

Initial rolling of circulating neutrophils on a blood vessel wall prior to adhesion and transmigration to damaged tissue is dependent upon P-selectin expressed on endothelial cells and its specific neutrophil receptor, the P-selectin glycoprotein ligand-1 (PSGL-1). Pretreatment of neutrophils, HL60 cells, or a recombinant fucosylated soluble form of PSGL-1 (sPSGL-1.T7) with the cobra venom metalloproteinase, mocarhagin, completely abolished binding to purified P-selectin in a time-dependent and EDTA- and diisopropyl fluorophosphate-inhibitable manner consistent with mocarhagin selectively cleaving PSGL-1. A polyclonal antibody against the N-terminal peptide Gln-1-Glu-15 of mature PSGL-1 immunoprecipitated sPSGL-1.T7 but not sPSGL-1.T7 treated with mocarhagin, indicating that the mocarhagin cleavage site was near the N terminus. A single mocarhagin cleavage site between Tyr-10 and Asp-11 of mature PSGL-1 was determined by N-terminal sequencing of mocarhagin fragments of sPSGL-1.T7 and is within a highly negatively charged amino acid sequence 1-QATEYEYLDYDFLPETEPPE, containing three tyrosine residues that are consensus sulfation sites. Consistent with a functional role of this region of PSGL-1 in binding P-selectin, an affinity-purified polyclonal antibody against residues Gln-1-Glu-15 of PSGL-1 strongly inhibited P-selectin binding to neutrophils, whereas an antibody against residues Asp-9-Arg-23 was noninhibitory. These combined data strongly suggest that the N-terminal anionic/sulfated tyrosine motif of PSGL-1 as well as downstream sialylated carbohydrate is essential for binding of P-selectin by neutrophils.

Bone Marrow Transplantation for Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia

Between 1986 and 1995, 19 patients with Philadelphia chromosome-positive (Ph + ) acute lymphoblastic leukemia underwent 20 autologous (n = 9) or allogeneic (n = 11) blood or marrow transplant procedures in first (n = 12) or second (n = 3) remission, or in relapse (n = 5). Four patients died due to transplant-related causes, 11 relapsed at 3-39 months, one survives with disease which did not remit after transplant, and three are alive in continuous remission at 1, 26 and 65 months. Two of the relapsing patients are alive; one autografted patient after an allograft in second remission and one allografted patient after a donor leukocyte infusion. The projected overall survival is 37.5% at 3 years and 12.5% at 5 years. The 3-year probabilities of relapse and disease-free survival for autografted patients are 65.9% and 25.6% respectively, and for allografted patients, 63.4% and 21.8% respectively. The stage of the disease at the time of transplant or the type of transplant did not affect the outcome significantly, and late relapses beyond 3 years were seen after allogeneic as well as autologous transplantation. In our experience, the outcome of patients with Ph + acute lymphoblastic leukemia continues to be poor despite high-dose therapy due to high relapse rates, and the development of additional measures to enhance the antileukemic efficacy of bone marrow transplantation is necessary.

Effects of glycosylated recombinant human granulocyte colony-stimulating factor after high-dose cytarabine-based induction chemotherapy for adult acute myeloid leukaemia

The Australian Leukaemia Study Group (ALSG) investigated whether G-CSF would accelerate haemopoietic recovery after induction treatment for acute myeloid leukaemia (AML) intensified with high-dose cytarabine, and therefore improve response rates and survival. Patients were randomised to receive lenograstim (glycosylated recombinant human G-CSF) 5 μg per kg body weight subcutaneously daily from day 8 after starting chemotherapy, or no cytokine, following chemotherapy with cytarabine 3 g/m2 every 12 h on days 1, 3, 5, and 7, together with idarubicin 9 or 12 mg/m2 on days 1, 2, and 3, plus etoposide 75 mg/m2 on days 1 to 7 inclusive. Patients had untreated AML, and were aged 16 to 60 years. Overall, 54 evaluable patients were randomised to receive lenograstim and 58 to no cytokine. Patients in the lenograstim arm had a significantly shorter duration of neutropenia <0.5 × 109/l compared to patients in the no cytokine arm (median 18 vs 22 days; P = 0.0005), and also shorter duration of total leucopenia <1.0 × 109/l (17 vs 19 days; P = 0.0002), as well as a reduction in duration of treatment with therapeutic intravenous antibiotics (20 vs 24 days; P = 0.015) and a trend to reduced number of days with fever >38.0°C (9 vs 12 days; P = 0.18). There were no differences between the two groups in platelet recovery, red cell or platelet transfusions, or non-haematological toxicities. For patients achieving CR after their first induction course, a reduction in the time to the start of the next course of therapy was observed in the lenograstim arm, from a median of 40.5 days to a median of 36 days (P = 0.082). The overall complete response rates to chemotherapy were similar, 81% in the lenograstim arm vs 75% for the no cytokine arm (P = 0.5), and there was no significant difference in the survival durations. We conclude that the granulopoietic stimulating effect of G-CSF is observed after induction therapy for AML intensified by high-dose cytarabine, resulting in an improvement in a number of clinically important parameters with no major adverse effects.

GMP-140 (P-selectin) inhibits human neutrophil activation by lipopolysaccharide: Analysis by proton magnetic resonance spectroscopy

Proton magnetic resonance spectroscopy has been used to monitor the effect of GMP-140 on the stimulation of human peripheral blood neutrophils. Stimulation of neutrophils by lipopolysaccharide gives rise to a high resolution lipid spectrum from the intact cells. Fluid phase GMP-140, which prevents adhesion and development of inflammatory responses of neutrophils, was found to inhibit these changes in the lipid spectrum by up to 40%. Anti-GMP-140 Fab fragments reversed this effect while non-immune Fab fragments did not affect the observed inhibition by GMP-140.

17p− Syndrome Arising from a Novel Dicentric Translocation in a Patient with Acute Myeloid Leukemia

The cytogenetic contribution to the poor prognosis when myelodysplastic syndrome (MDS) progresses to acute myeloid leukemia (AML) is not well understood. We present a 66-year-old male who had thrombocytopenia with dysplastic features in peripheral blood neutrophils (hypogranular, hyposegmented neutrophils) comprising the Pelger-Huet anomaly, increased blasts in the marrow, and markers consistent with AML. Diagnostic marrow cytogenetics showed a complex karyotype including del(5q), a novel unbalanced dicentric translocation, t(17;20), resulting in both del(20q) and del(17p). Fluorescence in situ hybridization (with probe TP53) showed deletion of 17p13 on the dicentric chromosome, completing the criteria for the 17p- syndrome. Fluorescence in situ hybridization with probes for two tumor suppressor genes on chromosome 5q also showed deletion (CSF1R [at 5(q33.2-q33.4) and EGR-1 [5(q31-q32)]). Remission was difficult to achieve and cytogenetic relapse occurred 6 months postdiagnosis, and clinical relapse approximately one month later. Our case provides a novel mechanism for the 17p- syndrome, and highlights the difficulty of attributing prognostic significance to a particular cytogenetic abnormality in AML.

Practical management of myelofibrosis with ruxolitinib

Treatment for the majority of patients with myelofibrosis is primarily based on symptom control as curative allogeneic stem cell transplantation is typically offered only to younger patients, especially those with poor prognosis disease. Around 50% of patients with myelofibrosis have the JAK2V617F mutation, but almost all patients have aberrant activation of the JAK‐STAT signalling pathway. Recent efforts have focussed on the clinical use of JAK2 inhibitors to treat myelofibrosis. In this article, we present our recommendations for the practical management of myelofibrosis with ruxolitinib, a selective inhibitor of both JAK1 and JAK2. Ruxolitinib can significantly improve the quality of life of patients with myelofibrosis. There is also increasing evidence of a positive impact on survival. Consistent with the physiological role of JAK signalling the major toxicity of ruxolitinib is cytopenia. Managing cytopenia is key to maximising the therapeutic benefit of ruxolitinib. Further research into the safety of ruxolitinib in patients with thrombocytopenia is warranted, as is its role in special subgroups of patients, such as those undergoing stem cell transplantation and those experiencing thrombosis as a major manifestation of myelofibrosis.

Sequential development of myelodysplasia and acute myeloid leukemia but with no karyotypic evolution after autografting in a patient with Philadelphia positive acute lymphoblastic leukemia.

A woman with Philadelphia chromosome-positive c-ALL with +8 and i17q in addition underwent an unpurged blood stem cell autograft after 200mg/m2 melphalan in first relapse. Maintenance therapy with 6-mercatopurine was started following the autograft. Moderate pancytopenia developed after 4 months, and myelodysplasia (refractory anemia) was diagnosed which rapidly evolved into AML. The cytogenetic findings remained unchanged. She also developed CNS disease, but the blasts in the cerebrospinal fluid were lymphoid in character on immunophenotyping. She then received palliative treatment until death. The remarkable features here are the evolution into myelodysplasia and AML with retention of the original complex karyotype, and subsequent coexistence of lymphoid disease in the CNS and myeloid disease systemically. It is possible that the lineage switch and development of myelodysplasia in this case may have been secondary to treatment, but persistence of the original cytogenetic clone makes this unlikely. This may have been the result of some unusual effect of the treatment on the original clone, or expansion of a small unidentified myeloid clone present originally which gained a proliferative advantage due to the ALL-type treatment. This case confirms the aggressive and polymorphic nature of Ph+ ALL which may be the result of origin from an early progenitor cell (stem cell disease).

Hickman catheter complications in a haematology unit, 1996–98

Ninety-nine dual-lumen Hickman catheters were inserted in 77 patients (46 male and 31 female). A review of 96 catheters (44 male and 30 female patients) was conducted (Table 1).The most common diagnoses were: (i) acute myeloid leukaemia (in 33 patients), (ii) acute lymphoblastic leukaemia (in 18 patients) and (iii) non-Hodgkin’s lymphoma (in 18 patients). A further eight patients had other diagnoses. The preoperative full blood count showed: (i) a mean haemoglobin level of 112 g/L (median 110 g/L; range 77–153 g/L), (ii) a mean neutrophil count of 4.5 × 109/L (median 2.2 × 109/L; range 0–46 × 109/L), and (iii) a mean platelet count of 150 × 109/L (median 96 × 109/L; range 3–912 × 109/L).

Routine fluorescence in situ hybridization with the MLL probe does not reliably detect two separate signals on one chromosome 11 in patients with trisomy 11

Trisomy 11 is considered to be a rare cytogenetic abnormality in myelodysplastic syndromes (MDS) and acute myelogenous leukemia (AML). Duplication of the MLL gene (localized to 11q23) has been found on one chromosome 11 in patients with trisomy 11, detected by DNA techniques. We investigated copy number of MLL in seven patients with trisomy 11 to see if duplication could be assessed by the detection of two separate signals on fluorescence in situ hybridization (FISH). If so, FISH could provide a quick easy screen of MLL status in routine referrals. The diagnostic bone marrow aspirate showed trisomy 11 in five adult patients with MDS/AML as part of a complex karyotype and in two children with acute lymphoblastic leukemia (ALL) as part of a hyperdiploid karyotype. Fluorescence in situ hybridization utilized the suspensions remaining after the cytogenetic harvest. Two FISH probes were used on the adult patients (MLL - Oncor and Vysis), and one (Vysis) for the two children with ALL. Analysis showed that the proximity of the two putative hybridization signals made it very difficult to unambiguously see two separate signals. The hybridisations (Oncor probe) were convincing of MLL duplication (namely two distinct signals) in only one patient, but this was not borne out with the other MLL probe (Vysis). We conclude that conventional FISH with MLL probe is not suited to act as a screen for MLL duplication in patients with trisomy 11.

Relationship of CD34+ cells infused and red blood cell transfusion requirements after autologous peripheral blood stem cell transplants: a novel method of analysis

BACKGROUND: CD34+ cells infused predicts myeloid and platelet engraftment at the time of autologous stem cell transplantation. An association between the number of CD34+ cells infused and erythroid engraftment has yet to be established.