The platelet defect in leukemia. Platelet ultrastructure, adenine nucleotide metabolism, and the release reaction

Platelet Defects in Acute Myeloid Leukemia-Potential for Hemorrhagic Events

Background and objectives: In acute myeloid leukemia (AML), extensive bleeding is one of the most frequent causes of death. Impaired activation and aggregation processes were identified in previous studies on platelet behaviour associated with this disease. This study’s aim was to examine platelet function in correlation with other haemorrhage risk factors (fever, sepsis, recent bleeding, uraemia, leucocytosis, haematocrit value, treatment). Design and methods: The analysis of platelet surface proteins (Glycoprotein Ib-IX (CD42b, CD42a), Glycoprotein IIb-IIIa (CD41, CD61), p-selectin (CD62P), granulophysin (CD63)) was conducted by flowcytometry from samples of whole blood in patients with acute myeloid leukaemia in different stages of diagnosis and therapy (n = 22) in comparison with healthy human controls (n = 10). Results and interpretations: Our results show a significant decrease in fluorescence level associated with platelet activation markers (CD63 (14.11% vs. 40.78 % p < 0.05); CD62P (15.26% vs. 28.23% p < 0.05)); adhesion markers (CD42b (69.08% vs. 84.41% p < 0.05)) and aggregation markers (CD61 (83.79% vs. 98.62% p < 0.001)) in patients compared to controls. The levels of CD41 (80.62% vs. 86.31%, p = 0.290) and CD42a (77.98% vs. 94.15%, p = 0.99) demonstrate no significant differences in the two groups. Conclusion: The AML patients present changes in adhesion receptors and activation markers, suggesting a functional defect or denatured intracellular signalling in platelets. The exposed data indicate that flow cytometry can effectively identify multiple functional platelet impairments in AML pathogenesis.

Both Granulocytic and Non-Granulocytic Blood Cells Are Affected in Patients with Severe Congenital Neutropenia and Their Non-Neutropenic Family Members: An Evaluation of Morphology, Function, and Cell Death

Objective:

To examine granulocytic and non-granulocytic cells in children with severe congenital neutropenia (SCN) and their non-neutropenic parents.

Materials and Methods:

Fifteen patients with SCN and 21 non-neutropenic parents were evaluated for a) CD95, CD95 ligand, annexin V, propidium iodide, cell cycle, and lymphocyte subsets by flow cytometry; b) rapid cell senescence (of leukocytes) by senescence-associated β-galactosidase stain; c) aggregation tests by aggregometer; d) in vitro bleeding time by PFA-100 instrument; e) mepacrine-labeled dense granule number of thrombocytes by fluorescence microscope; and f) hematomorphology by light and electron microscope. HAX1, ELANE, G6PC3, CSF3R, and JAGN1 mutations associated with SCN were studied in patients and several parents.

Results:

Significant increase in apoptosis and secondary necrosis in monocytes, lymphocytes, and granulocytes of the patients and parents was detected, irrespective of the mutation type. CD95 and CD95 ligand results implied that apoptosis was non-CD95-mediated. Leukocytes of 25%, 12.5%, and 0% of patients, parents, and controls showed rapid cell senescence. The cell cycle analysis testable in four cases showed G1 arrest and apoptosis in lymphocytes of three. The patients had HAX1 (n=6), ELANE (n=2), G6PC3 (n=2), and unidentified (n=5) mutations. The CD3, CD4, and NK lymphocytes were below normal levels in 16.6%, 8.3%, and 36.4% of the patients and in 0%, 0%, and 15.4% of the parents (controls: 0%, 0%, 5.6%). The thrombocytes aggregated at low rates, dense granule number/thrombocyte ratio was low, and in vitro bleeding time was prolonged in 37.5%-66.6% of patients and 33.3%-63.2% of parents (vs. 0% in controls). Under electron and/or light microscope, the neutrophils, monocytes, lymphocytes, and thrombocytes in the peripheral blood of both patients and parents were dysplastic and the bone marrow of patients revealed increased phagocytic activity, dysmegakaryopoiesis, and necrotic and apoptotic cells. Ultrastructurally, thrombocyte adhesion, aggregation, and release were inadequate.

Conclusion:

In cases of SCN, patients’ pluripotent hematopoietic stem cells and their non-neutropenic parents are both affected irrespective of the genetic defect.

Impaired mitochondrial activity explains platelet dysfunction in thrombocytopenic cancer patients undergoing chemotherapy

Severe thrombocytopenia (≤50×10⁹ platelets/L) due to hematological malignancy and intensive chemotherapy is associated with an increased risk of clinically significant bleeding. Since the bleeding risk is not linked to the platelet count only, other hemostatic factors must be involved. We studied platelet function in 77 patients with acute leukemia, multiple myeloma or malignant lymphoma, who experienced chemotherapy-induced thrombocytopenia. Platelets from all patients - independent of disease or treatment type - were to a variable extent compromised in Ca²⁺ flux, integrin a β activation and P-selectin expression when stimulated with a panel^IIbof³ agonists. The patients' platelets were also impaired in spreading on fibrinogen. Whereas the Ca²⁺ store content was unaffected, the patients' platelets showed ongoing phosphatidylserine exposure, which was not due to apoptotic caspase activity. Interestingly, mitochondrial function was markedly reduced in platelets from a representative subset of patients, as evidenced by a low mitochondrial membrane potential (P<0.001) and low oxygen consumption (P<0.05), while the mitochondrial content was normal. Moreover, the mitochondrial impairments coincided with elevated levels of reactive oxygen species (Spearman's rho=-0.459, P=0.012). Markedly, the impairment of platelet function only appeared after two days of chemotherapy, suggesting origination in the megakaryocytes. In patients with bone marrow recovery, platelet function improved. In conclusion, our findings disclose defective receptor signaling related to impaired mitochondrial bioenergetics, independent of apoptosis, in platelets from cancer patients treated with chemotherapy, explaining the low hemostatic potential of these patients.

Immunoprophylactic potential of wheat grass extract on benzene-induced leukemia: An in vivo study on murine model

Objectives:

Wheat grass (Triticum aestivum) is a gift of nature given to mankind. A number of scientific research on wheatgrass establishes its anticancer and antioxidant potential. Current work was focused to determine antileukemic effect of wheat grass.

Materials and Methods:

The commercial wheatgrass powder was extracted with 95% of methanol. Methanol extract of wheat grass was studied for acute oral toxicity as per revised Organization for Economic Cooperation and Development Guidelines number 423. Leukemia was successfully induced in Wister rats by intravenous injection of benzene. The blood was collected and analyzed for hematological parameters. Phagocytotic activity of the extract was determined.

Results:

Phytochemical screening revealed the presence of flavonoids, phenolics, carbohydrates, and amino acids. From acute toxicity studies, it was found that the methanol extract of wheatgrass was safe up to a dose level of 2000 mg/kg of body weight. Outcomes of hematological parameters in various experimental groups of murine model demonstrated antileukemic effect of extract. Methanol extract of wheatgrass aroused the process of phagocytosis of killed Candida albicans and also demonstrated a significant chemotactic activity at all tested concentrations.

Conclusion:

In the current work, methanol extract of wheat grass demonstrated antileukemic potential that might be due to the presence of flavonoids and polyphenolics in it. Further isolation, structural characterization of active constituents is necessary to extrapolate the mechanism of action.

Prevalence of disease and relationships between laboratory phenotype and bleeding severity in platelet primary secretion defects

BACKGROUND

The prevalence of platelet primary secretion defects (PSD) among patients with bleeding diathesis is unknown. Moreover, there is paucity of data on the determinants of bleeding severity in PSD patients.

OBJECTIVE

To determine the prevalence of PSD in patients with clinical bleeding and to study the relationships between the type of platelet defect and bleeding severity.

METHODS

Data on patients referred for bleeding to the Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan (Italy) in the years between 2008 and 2012 were retrieved to study the prevalence of PSD. Demographic, clinical and laboratory information on 32 patients with a diagnosis of PSD was used to compare patients with or without associated medical conditions and to investigate whether or not the type and extension of platelet defects were associated with the bleeding severity score (crude and age-normalized) or with the age at first bleeding requiring medical attention.

RESULTS

The estimated prevalence of PSD among 207 patients with bleeding diathesis and bleeding severity score above 4 was 18.8% (95% confidence interval [CI]: 14.1-24.7%). Patients without associated medical conditions had earlier age of first bleeding (18 vs 45 years; difference: -27 years; 95% CI: -46 to -9 years) and different platelet functional defect patterns (Fisher's exact test of the distribution of patterns, P = 0.007) than patients with accompanying medical conditions. The type and extension of platelet defect was not associated with the severity of bleeding.

CONCLUSIONS

PSD is found in approximately one fifth of patients with clinical bleeding. In patients with PSD, the type and extension of laboratory defect was not associated with bleeding severity.

Platelet size and adenine nucleotides in patients undergoing bone marrow ablation: a useful model for studying platelet ageing

Peripheral blood platelets were examined in 7 patients who underwent bone marrow ablation with high dose chemotherapy and total body irradiation prior to bone marrow transplantation (BMT). Platelets were studied for 9 days, by which time the platelet counts had fallen to levels at which platelet transfusion support was necessary. Values for (111)Indium autologous mean platelet lifespan were similar to those reported in thrombocytopenic patients by other authors. During the period of study, there was no significant change in mean platelet volume or platelet nucleotides. The results indicate that in man, platelet size and platelet nucleotides are not affected when platelets age in the peripheral circulation.

Effect of platelet count on secretion capacity: formulization and use of the formulae for evaluation of platelet secretion in thrombocytopenic patients

The correlation between platelet count and bleeding time is nonlinear. The bleeding time prolongs more prominently as platelet count decreases toward 10 000 microl(-1); however, it becomes stable near 100 000 microl(-1). Clinical observations suggest that platelet functional capacity may also play a role in bleeding complications during thrombocytopenia. However, no routine method has been described for evaluation of platelet function during thrombocytopenia. To test if platelet functional capacity is affected by the cell count, as suggested by the platelet count-bleeding time correlation. To evaluate lumiaggregometry as a possible tool for studying platelet functions and prediction of bleeding in thrombocytopenic patients. Collagen-induced ATP release was studied in different dilutions of 22 healthy platelet-rich plasmas. The relationship between platelet count and ATP release was formulized. ATP release was also tested in 24 thrombocytopenic (10 000-50 000 microl(-1). ) patients, and the results were compared with expected levels derived from the formulae. ATP release increased in a cubic fashion as platelet count elevated. ATP secretion values were within normal limits or increased in patients with idiopathic thrombocytopenic purpura. However, some patients with megakaryocyte deficiency had a secretion defect. ATP secretion was decreased in four out of seven patients with bleeding symptoms compared with no persons without bleeding (P = 0.003). Platelet functional capacity is affected by the cell count. Lumiaggregometry is potentially useful in evaluating platelet functions during thrombocytopenia.

High cystine in platelets from patients with nephropathic cystinosis: a chemical, ultrastructural, and functional evaluation

AIM

To investigate the morphology and function of platelets in nephropathic cystinosis (NC).

METHODS

Seven patients (mean age, 6.5 years; SD, 20 months) with NC were investigated. Their platelets were examined by transmission electron microscopy (TEM) and the characteristics of the dense granules (DGs) were determined by mepacrine labelling and the uranaffin reaction. Bleeding time, turbidometric aggregation, and luminescence aggregation were studied and intraplatelet cystine was measured.

RESULTS

Increased intraplatelet cystine, primary and secondary aggregation defects, and the absence of ATP release were demonstrated. TEM revealed DGs of various shapes and sizes and lamellary or amorphous cytoplasmic inclusions. Viscous material had been released into the vacuolar spaces and enlarged open canalicular system. Mepacrine labelling revealed that the numbers of DGs/platelet were comparable between the patients and the controls (mean, 2.9 (SD, 0.22) v 3.32 (0.18); p = 0.34). The uranaffin reaction revealed that the numbers of type 1, 3, and 4 DGs were comparable between the patients and the controls, but that there were fewer type 2 DGs in the patients (mean, 8.5 (SD, 1.95) v 17.22 (1.58); p = 0.01). TEM for platelet aggregation revealed a lack of induction and/or defective execution and/or delayed transmission. The patients' intraplatelet cystine concentrations were higher than the controls (mean, 1.56 (SD, 0.84) v 0.08 (0.01) nmol/mg protein; p = 0.009).

CONCLUSIONS

This is the first report to demonstrate raised intraplatelet cystine, abnormal platelet ultrastructural findings, and defective aggregation in NC.

Prediction of haemorrhage in the early stage of acute myeloid leukaemia by flow cytometric analysis of platelet function

Haemorrhage is often responsible for the lethal course of acute myeloid leukaemia (AML). Previously, multiple platelet function defects were identified by flow cytometric analysis of platelet activation markers in AML. The role of flow cytometric analysis of platelet function in characterization of prognostic markers of haemorrhage in AML patients has not been well elucidated. The objective of this prospective study was to analyse platelet function in 50 AML patients at diagnosis and to compare results with clinical bleeding score, graded by common toxicity criteria. Platelet activation markers CD62P, CD42b, CD63 and PAC-1 were analysed following in vitro activation by thrombin receptor activating peptide. The following plasma haemostasis parameters were measured: soluble P-selectin, activated partial thromboplastin time, thrombin time, prothrombin time, D-dimer, fibrinogen, and von Willebrand factor antigen. In a multivariate analysis, P-selectin (CD62P) <36 molecules of equivalent soluble fluorochrome x 10(3) (P < 0.0015) and platelet count <40 x 10(9)/l (P = 0.01) were significant predictors of haemorrhage at diagnosis. Haemorrhage at diagnosis predicted grade 3-4 haemorrhage in the first 28 d following diagnosis (P = 0.018). The presented results indicate that low P-selectin is a prognostic marker of haemorrhage in AML.

Multiple platelet defects identified by flow cytometry at diagnosis in acute myeloid leukaemia

Summary Previous findings of megakaryocytic hypogranulation and dysmegakaryocytopoietic features in acute myeloid leukaemia (AML) strongly indicate defects in platelet production. The bleeding tendency of these patients may result from dysregulated platelet production, resulting in thrombocytopenia as well as qualitative platelet defects. The present study examined platelet function at diagnosis in 50 AML patients by whole blood flow cytometry. Following in vitro platelet agonist stimulation, platelet activation markers were analysed and compared with 20 healthy individuals. To detect recent in vivo platelet activation, plasma soluble P-selectin (sP-selectin) was measured. Flow cytometric analysis of platelet activation markers demonstrated reduced CD62P [35.6 vs. 118.5 x 10(3) molecules of equivalent soluble fluorochrome (MESF); P < 0.0001], CD63 (11.3 vs. 50.7 x 10(3) MESF; P < 0.0001), and PAC-1 (41.5 vs. 90.5%; P = 0.0001) while reductions in CD42b were abnormal (45.6 vs. 70%; P < 0.0001). sP-selectin levels were similar in patients and healthy controls (0.04 vs. 0.27 fg/platelet; P = 0.84). The presented data indicate that AML pathogenesis may result in multiple platelet defects, involving adhesion, aggregation, and secretion and demonstrate that flow cytometry is a feasible method for platelet function analysis in patients with thrombocytopenia.

Platelet aggregation in children with acute lymphoblastic leukemia during induction of remission therapy

BACKGROUND

Development of thromboembolytic events is a major complication during induction of remission therapy (IRT) for acute lymphoblastic leukemia (ALL) of childhood. Increased in vitro platelet aggregation in response to drugs employed at this stage has been documented. To investigate the presence of an in vivo platelet agonist effect, we studied changes in aggregation patterns of patients with ALL receiving IRT.

METHODS

Platelets from 22 children with a new diagnosis of ALL were obtained during IRT once the platelet count reached >100 x 10(9)/L. Platelets were stimulated with adenosine diphosphate (ADP), collagen, ristocetin, and epinephrine. Platelet responses were evaluated by optical aggregometry.

RESULTS

Percentages of platelet aggregation in ALL patients were as follows: ADP, 89+/-22; collagen, 90+/-24; ristocetin, 84+/-26, and epinephrine, 81+/-20. Percentages in healthy individuals were ADP: 98+/-12; collagen: 105+/-10; ristocetin: 100+/-15, and epinephrine, 98+/-8.

CONCLUSIONS

Platelet aggregation with classical agonists was diminished during IRT for ALL of childhood, although it remained within the normal lower limit for age. Considerable heterogeneity in platelet reactivity existed, probably reflecting the presence of several pharmacologically altered platelet subpopulations. No apparent clinical correlation of aggregometric changes was documented.

Platelet dysfunction in myelodysplastic syndromes: a clinicopathological study

Forty-eight patients with myelodysplastic syndromes and a platelet count greater than 80 x 10(9)/L were the subjects of a study of platelet function. A whole-blood platelet lumi-aggregometer was used for simultaneous measurement of platelet aggregation by the impedance method and of adenosine triphosphate-dense granule release. The results were correlated with skin bleeding time and episodes of clinical bleeding or thrombosis. Thirty-five patients had at least 1 abnormal result indicating platelet hypoactivity; 7 patients had mixed platelet hypoactivity and hyperactivity; and 4 patients had platelet hyperactivity. Only 2 patients had normal results. There was good correlation between platelet hypoactivity and prolonged skin bleeding time (P = .005); however, several patients with platelet hypoactivity had normal skin bleeding times. This finding suggested that whole-blood platelet aggregation studies may be more sensitive than bleeding time in identification of patients at risk of bleeding. Clinical hemorrhage was frequent (32 patients) in this cohort despite platelet counts greater than 100 x 10(9)/L. This finding indicated platelet hypofunction was clinically important. In contrast, only 2 of the 13 patients with thrombotic events had evidence of platelet hyperactivity, suggesting that other clinical factors are probably more important determinants of thrombosis. These observations confirm that platelet dysfunction is common in patients with myelodysplastic syndromes and suggest a useful role for routine whole-blood platelet aggregation studies to identify patients at risk of bleeding.

Disorders of platelet function

Qualitative platelet disorders are described and reviewed above. The acquired platelet function defects are very common, and sometimes result in hemorrhage, especially in association with trauma or surgery. However, the specific biochemical defect is absent, and no characterized platelet abnormalities have been recognized. On the other hand, the hereditary qualitative platelet defects are rare, but the platelet abnormalities are characteristic. The study of these patients had led to an increased understanding of the normal primary hemostatic mechanism. Recently, the molecular basis analysis of the platelet defects has been developed. This will help us understand the molecular events involved in platelet adhesion and aggregation.

Platelet transfusion and alternatives to transfusion in patients with malignancy

Platelet transfusions have long had an important role in the treatment of patients with thrombocytopenia due to disease or myelotoxic treatment or in patients with reduced platelet function. However, platelet transfusions are associated with numerous risks, both immunologic (e.g., transfusion reactions, alloimmunization, immunosuppression) and infectious (e.g., viral, bacterial). In addition, several laboratory and clinical factors can influence post-transfusion platelet recovery. Recent technological advances have introduced the potential for using alternatives to platelet transfusions, such as cytokines or platelet substitutes, which may avoid the risks of transfusion. Platelet development from megakaryocytes is a process that is highly regulated by cytokines and animal research suggests that selected cytokines involved in this process may be useful in the treatment of thrombocytopenia. Newer developments, including the utilization of recombinant cytokines with relatively selective stimulation of platelet production (e.g., interleukin 6 [IL-6]) and the recent discovery of a megakaryocyte colony stimulating factor (thrombopoietin), represent major therapeutic opportunities in the treatment of thrombocytopenia. Platelet substitutes, e.g., thromboerythrocytes, also show promise in the management of platelet deficiencies.

Myelodysplasia and deficiency of uridine diphosphate-galactose 4-epimerase

A 4-year-old girl known to have peripheral uridine diphosphate-galactose 4-epimerase deficiency was examined for bruising and thrombocytopenia. She had dysplastic peripheral blood and bone marrow changes, with a global platelet function defect. Uridine diphosphate-galactose-4-epimerase participates in a metabolic pathway that provides substrates for posttranslational glycosylation of secreted and membrane glycoproteins, including hematopoietic growth factors and their receptors; there may be a causal relationship between the two disorders.

Platelet storage pool deficiency, leukemia, and myelodysplastic syndromes

Abnormalities in platelet dense granules, small intracellular organelles containing ATP, ADP, calcium, serotonin, and pyrophosphate, have frequently been reported in patients with leukemia and myeloproliferative disorders, particularly acute and chronic myelogenous leukemia. Recent studies of a family which includes several members with an autosomal dominant dense granule deficiency condition show an association between the presence of this form of dense granule deficiency and the development of acute myelogenous leukemia. Studies in two additional patients, one with the Monosomy 7 syndrome and the second with a myelodysplastic syndrome, revealed a defect in platelet dense granules. This defect appears to be due to an abnormality in the formation of these granules rather than the presence of empty vesicular structures or decreased contents due to activation associated secretion. The results suggest that the defect in platelet dense granules associated with leukemia or myelodysplastic syndromes may result from a chromosome alteration in the megakaryocyte cell line leading to decreased formation of dense granules. Studies in the family with an inherited bleeding disorder suggest that a gene coding for a protein important for the formation of dense granules is located adjacent to a gene which, when abnormal, may predispose to the development of leukemia.

Inherited platelet-storage pool deficiency associated with a high incidence of acute myeloid leukaemia

A family with an inherited bleeding disorder extending over four generations, and multiple cases of myeloblastic and myelomonoblastic leukaemia was studied. Ten members of the family had, by history, a haemorrhagic diathesis. There were three documented cases of myeloblastic leukaemia, two documented cases of myelomonoblastic leukaemia and two more cases of leukaemia by history. In four of the cases the bleeding diathesis clearly antedated the leukaemia, in two by many years. The bleeding disorder is characterized by a long bleeding time, abnormal platelet aggregation, low platelet ADP and decreased numbers of platelet dense bodies consistent with a dense granule storage pool deficiency. The number of dense granules was decreased by immunofluorescence employing quinacrine or using an antibody to the dense granule membrane protein, granulophysin, confirming an absolute decrease in dense granule numbers rather than the presence of empty granule sacs. This congenital storage pool deficiency is associated with a high incidence of acute myeloid leukaemia in this family.

Impaired conversion of exogenous arachidonic acid by platelets to thromboxane B2 and correction of that deficiency by interferon-alpha

In the course of an investigation of cyclooxygenase and 12-lipoxygenase activity in platelets of patients with myeloproliferative syndrome receiving treatment with interferon-alpha 2 patients showed unusual results which have not been reported so far. Both patients had thrombocytosis, in one case associated with polycythaemia. In platelets of both patients, a reduced conversion of exogenous 14C arachidonic acid to TXB2 was observed accompanied by a shift in conversion to PGE2 and 12-HETE in one patient and to 12-HETE alone in the other before therapy. These findings were paradoxically associated with evidence of enhanced platelet activation in vivo. Treatment of both patients with interferon-alpha resulted in reversal of the biochemical abnormalities and in clinical remission.

What's new in the causes of hemorrhage in acute myelogenous leukemia?

Hemorrhages in AML are still a major problem, although not the most important and different factors are involved in its genesis. The causes that predispose an AML patient to bleed will be reviewed, the hypotheses concerning the coagulation disorder specially found in the FAB M3 type will be discussed and the increasingly recognized role of plasminogen activators and enzymes released from blasts will be emphasized.

Platelets and neoplasia

Numerous platelet abnormalities have been recognized in animals with malignancy. Because platelets play a key role in hemostasis, it is vital that clinicians recognize those neoplastic conditions that are associated with platelet disorders. A review of these platelet abnormalities, their underlying pathophysiology, and treatment is presented in this article.

Platelet volume and intraplatelet adenine nucleotides in various hematologic disorders

By recent advanced techniques, blood platelets have proved to be varied in size and metabolism in various hematologic disorders. We examined platelet volume and intraplatelet adenine nucleotides in 36 patients with various hematologic disorders in order to clarify the quantitative platelet abnormalities. Platelet volumes were smaller in patients with acute leukemia and aplastic anemia, and larger in patients with immune thrombocytopenic purpura (ITP). The amount of intraplatelet ADP was decreased and ATP/ADP ratio was increased in acute leukemia, aplastic anemia and myeloproliferative disorders (MPD), which strongly suggested the presence of storage pool deficiency in these patients. Intraplatelet ADP per volume was decreased in acute leukemia, aplastic anemia and MPD, and ATP per volume was decreased in aplastic anemia. ATP content was increased in ITP in proportion to the increased platelet volume. These parameters were examined in 36 patients with the following hematologic disorders: 7 acute leukemia treated with cytotoxic chemotherapy, 5 aplastic anemia, 3 paroxysmal nocturnal hemoglobinuria (PNH), 9 immune thrombocytopenic purpura (ITP), 5 hypersplenism and 7 myeloproliferative disorders (MPD).

Acquired von Willebrand disease and storage pool disease in chronic myelocytic leukemia

Platelet function was evaluated in 20 patients with chronic myelocytic leukemia (CML), all Ph positive. Seven showed abnormal epinephrine-induced aggregation, while four had impaired both ADP- and collagen-induced aggregation. The platelets of all patients aggregated with arachidonic acid, thus ruling out cyclooxygenase or lipoxygenase deficiency. The intracellular concentrations of ATP and ADP were significantly below normal, and the ratio of ATP/ADP was greater than normal in all 12 patients. ATP released from platelets by Lumi-aggregometer was reduced. In four patients with abnormal ristocetin-induced aggregation, vWF:Ag, RCoF, and FVIII:C were all reduced. No significant inactivation of factor VIII was induced in normal plasma by incubation with patient's plasma. The crossed immunoelectrophoretic analysis revealed that vWF:Ag in these patients was mainly composed of more anodic component as compared with that of normal plasma. The ratio of vWF:Ag/RCoF was significantly greater than normal. A marked increase of factor VIII and a rapid return of vWF:Ag and RCoF to the baseline after the 1-deamino-8-arginine vasopressin (DDAVP) infusion were observed. Transient increase in vWF:Ag after the infusion of DDAVP appeared with less anodic forms and in the same relative proportion as that in normal plasma. The present study shows that in some patients with CML storage pool disease occurs with acquired von Willebrand disease.

The platelet defect in acute myeloid leukaemia

In a study of platelets from 13 patients with acute myeloid leukaemia abnormal aggregation and release reactions were found. A previously unrecognised quantitative defect of thromboxane B2 production may, at least in part, explain these findings. In contrast to a previous report, we were unable to show a convincing storage pool defect in these platelets. The platelet membrane glycoproteins were largely normal.

Radicular vessels are the most probable source of needle-induced blood in lumbar puncture: significance for the thrombocytopenic cancer patient

Despite knowledge of the bleeding hazard to thrombocytopenic cancer patients undergoing lumbar puncture (LP), a retrospective analysis of physician behavior at one hospital revealed no consistent use of platelet transfusions in patients with less than 20,000 platelets/mm3 on the day of LP. A review of the literature and laboratory cerebrospinal fluid (CSF) data in two institutions, and the performance of an LP experiment revealed that: (1) Batson's epidural venous plexus is an unlikely source and spinal radicular vessels are the most probable source of needle-induced blood in lumbar puncture; (2) the frequency of encountering needle-induced blood at LP is high, 73% (3) the frequency of brushing a nerve root, with the associated risk of lacerating the radicular artery or vein on its surface with the bevel of the LP needle, is high and may be on the order of 26%; and (4) while the passage of an LP needle, obturator in place, through a blood filled vein may carry red cells into a red cell-free medium, this does not always occur. These new considerations argue for more consistent adherence to the already published recommendation of platelet transfusion immediately prior to LP in patients with low platelets. This issue is of particular relevance to the rapidly growing population of thrombocytopenic cancer patients with extended survival on multiple chemotherapeutic regimens requiring lumbar puncture.

Acute megakaryoblastic leukaemia associated with intrinsic platelet dysfunction and constitution ring 21 chromosome in a young boy

A 3-year-old boy with pancytopenia and a paucity of circulating blast cells was found to have acute megakaryoblastic leukaemia. Histopathologic investigation of the bone marrow biopsy disclosed replacement by megakaryoblasts and mild-to-moderate reticulin fibrosis, the megakaryocytic origin of these cells was confirmed by their staining properties and by cross-reactivity with rabbit anti-rat platelet serum. Treatment with adriamycin and cytosine arabinoside induced a complete remission of this otherwise rapidly fatal disease. Before chemotherapy, the patient's platelets showed decreased aggregation in response to thrombin and adenosine diphosphate, as well as a defective thrombin-induced serotonin release reaction. Neither functional defect resolved after remission induction, indicating that the platelets were intrinsically abnormal. Most striking was the finding of a constitution chromosomal defect, a ring No. 21 chromosome, in addition to an abnormal malignant stem line. This appears to be the first reported instance of a constitutional r(21) chromosome associated with acute leukaemia.

Granulocyte and platelet adhesiveness in malignant paraproteinaemia, leukaemia and myeloproliferative diseases

Granulocyte and platelet adhesiveness were measured in 36 patients with haematologic diseases, using a glass bead column assay. Platelet adhesiveness (PA) was reduced in malignant paraproteinaemia (l3/20), leukaemia (10/11) and myeloproliferative diseases (3/5). Granulocyte adhesiveness (GA) was reduced in most patients with paraproteinaemia and leukaemia, but results of measurements in whole blood and in suspensions of leucocytes in autologous plasma were poorly correlated due to the influence of abnormal platelet function and/or concentration on the measurement of GA in whole blood. The results of experiments combining leucocytes and plasma from patients and controls indicate that impaired GA in paraproteinaemia is due to a plasma factor, whereas a cellular defect is responsible for the reduced GA in leukaemia.

Bioluminescent assay of adenine nucleotides: rapid analysis of ATP and ADP in red cells and platelets using the LKB luminometer

The assessment of both red cell and platelet function requires assay of adenine nucleotides. We describe the use of the new LKB luminometer to measure adenosine triphosphate (ATP) and adenosine diphosphate (ADP) by bioluminescence in both normal and abnormal red cells and platelets. ATP was measured a in a lysate of red cells suspended in buffer, pH 7.4, b in ethanol extracts of platelets from platelet-rich plasma (PRP) and c in ethanol extracts of supernatant platelet-poor plasma (PPP) following platelet aggregation by collagen. ADP was measured as ATP after phosphorylation by pyruvate kinase (PK) with phosphoenolpyruvate (PEP). Duplicate assays showed a variance of less than 3%. Red cell lysates and ethanol extracts of PRP and PPP stored at -40 degrees C were stable for 4 weeks. Duplicate assays of ATP and ADP in eight samples plus standards could be performed in 2 h. Normal values were: red cells (microM/ml red cells) (n = 20), ATP 1.15 +/- 0.17 (1 SD), ADP 0.22 +/- 0.07, ATP/ADP (mean ratio) 5.76:1, platelets (nm/10(9) platelets) (n = 20), ATP 53.3 +/- 7.6, ADP 27.8 +/- 5.8, ATP/ADP (mean ratio: 1.96:1). Abnormalities of red cell ATP and/or ADP could be demonstrated in chronic renal failure, hereditary glycolytic enzyme deficiencies and other haemolytic states. In myeloproliferative disorders defective platelet aggregation associated with storage pool deficiency and/or impaired release of ADP and ATP could be shown. We conclude that this is a reliable, rapid and economical technique for measuring red cell and platelet adenine nucleotides.

Disorders of platelet function: mechanisms, diagnosis and management

Platelets play an important role in hemostasis, and alterations in platelet function may be the cause of abnormal bleeding in a wide variety of congenital and acquired clinical disorders. Platelet dysfunction may be classified as disorders of (1) substrate connective tissue, (2) adhesion, (3) aggregation and (4) platelet-release reaction. The congenital defects of platelet function, although uncommon, have provided important insights into platelet physiology and pathophysiology and, as a group, are less common, better characterized and more readily classified than the acquired defects. The severity of bleeding resulting from platelet dysfunction varies greatly and is substantially increased when another defect of hemostasis coexists. A disorder of platelet function is suspected on the basis of the history and physical examination and is confirmed by the finding of a prolonged bleeding time in the presence of an adequate number of platelets. A specific diagnosis often requires measurements of the factor VIII and von Willebrand factor complex and other tests of platelet function. Some of these tests may be available only in specialized laboratories. Therapy for bleeding episodes resulting from platelet dysfunction is directed at (1) removing or treating the underlying cause of the platelet disorder; (2) replacing the missing plasma cofactors needed to support normal platelet function (such as by the transfusion of cryoprecipitate in patients with von Willebrand disease, and (3) transfusing functional platelets in the form of platelet concentrates in patients with disorders of intrinsic platelet dysfunction.

B-thromboglobulin content of human blood platelets

There was a reduction in the B-thromboglobulin content of human blood platelets in patients with leukaemia after chemotherapy which inhibited platelet production. Thus, in these patients, as the circulating platelet population ages, B-thromboglobulin leaks out of, or is actively secreted by, platelets which remain in the circulation.

Platelet function in hairy-cell leukaemia

A quantitative study of various aspects of platelet function was carried out in eight patients with typical hairy-cell leukaemia (HCL). In at least two patients platelet aggregation was convincingly reduced to more than one aggregating agent (ADP, adrenaline, collagen, thrombin, and ristocetin). Granular storage capacity for {(14)C} 5-HT was reduced in five of the six patients tested. The two patients with definitely abnormal aggregation had the greatest reduction in granular storage pool and the longest bleeding times of those tested but, like the other patients, they did not have a clinical haemostatic defect. It was concluded that a granular storage pool defect (SPD) was at least partly responsible for aggregation abnormalities in HCL since the platelet release reaction in response to thrombin appeared to be normal. All our patients ran a chronic course uncomplicated by any of the factors known to predispose to a platelet SPD acquired in the circulation. Although in the one patient tested before and after splenectomy there was some improvement in platelet aggregation after operation, there was no clear general relationship between defective platelet function and either previous splenectomy or platelet count. Since a direct involvement of the megakaryocytic series in the underlying cell proliferation of HCL seems unlikely, it is concluded that the platelet defect can most reasonably be attributed to the production of abnormal platelets as a result of marrow fibrosis and/or infiltration by hairy cells.

Thrombocytopathy in preleukaemia: association with a defect of thromboxane A2 activity

Platelet aggregation and the platelet prostaglandin pathway have been investigated in two patients with preleukaemic states who had a haemorrhagic tendency but a normal platelet count. In both patients platelet aggregation induced by collagen adenosine diphosphate (ADP) and arachidonic acid (AA) were abnormal. Malonyldiadehyde (MDA) production from exogenous AA was normal in both patients thus excluding cyclo-oxygenase deficiency. The platelet aggregating and rabbit aorta contracting activities of thromboxane A2 (TxA2) were very low in both patients. Production of thromboxane B2 (TxB2) assessed by thin layer chromatographic separation of the metabolites of [1(-14)C]AA and by radioimmunoassay, was normal. These abnormalities of platelet function appear to be due to the production of TxA2 with a low biological activity.

Platelet storage pool deficiency and prostaglandin synthesis in chronic granulocytic leukaemia

Platelet function was evaluated in eight patients with chronic granulocytic leukaemia (CGL), seven Ph1 positive and one Ph1 negative. Seven of the eight patients' platelets had an absence of the second wave of adrenaline induced aggregation on at least one occasion, while five had impaired collagen aggregation. The platelets of all seven patients with abnormal responses to adrenaline, aggregated with arachidonic acid, thus ruling out a cyclo-oxygenase deficiency. A marked decrease in the ADP, serotonin, and dense body content of platelets was found in all five patients evaluated. Mixtures of CGL patient platelets with platelets from normal donors who had ingested aspirin gave a normal biphasic response to adrenaline. Normal release of the storage pool contents from aspirin treated platelets was shown by stirring a mixture of CGL platelets and 14C-serotonin labelled aspirin treated platelets with adrenaline. The CGL platelets alone or in the mixture produced malondialdehyde in response to adrenaline. These experimental results suggest that CGL platelets have a storage pool deficiency but can synthesize prostaglandins and thromboxanes in response to arachidonic acid and adrenaline.

Defective binding of thrombin to platelets in myeloid leukaemia

Platelets from patients with myeloid leukaemia showed reduced aggregation with collagen or thrombin. These platelets also had a lower capacity to bind thrombin. This lower thrombin binding is due to a decrease in the total quantity of receptors available and not because of a change in the affinity. In the presence of the patients' plasma, the aggregation behaviour of normal platelets induced by thrombin as well as the clotting time of fibrinogen remained unchanged. The results suggest that the platelet dysfunction in myeloid leukaemia is partially due to a membrane defect involving the thrombin receptors which leads to an impaired induction of the initial stimulation.

Frozen autologous platelet transfusion for patients with leukemia

Platelets were removed from 25 patients with leukemia during remission and were frozen for subsequent transfusion. With 5 per cent dimethyl sulfoxide as a cryoprotective agent, we froze 3 to 5 units of pooled platelet concentrate by simply placing the platelets in the vapor phase of a liquid nitrogen freezer. Ninety-one transfusions of platelets stored for 13 to 400 days were administered. The mean freeze-thaw loss was 13 percent, and the corrected one-hour increment in platelet count was 13,700 per microliter, corresponding to a recovery of 53 per cent of the predicted value. In many patients most or all of the transfusion requirements were met with frozen platelets. Our results indicate that frozen platelets can circulate and function hemostatically. Autologous frozen platelets are of particular value in the management of alloimmunized patients and have become an integral part of our transfusion support program.

Acquired platelet dysfunction following mithramycin therapy

The administration of mithramycin to patients with testicular tumors has been accompanied by a hemorrhagic diasthesis, often in the absence of thrombocytopenia. Bleeding time, platelet aggregation, platelet adenine nucleotide levels, and coagulation factor assays were studied in three patients receiving mithramycin for embryonal testicular carcinomas. These studies demonstrated a drug dependent, reversible hemorrhagic diathesis associated with (1) prolongation of bleeding time, (2) decreased platelet aggregation responses to ADP, collagen, and epinephrine, and (3) depleted platelet stores of ADP in the absence of thrombocytopenia. These abnormalities were temporally correlated with the onset of mucocutaneous bleeding in all patients.

Acute myelomomocytic leukemia terminating in histiocytic medullary reticulosis: cytochemical, cytogenetic and electron microscopic studies

A case of acute myelomonocytic leukemia terminating in histiocytic medullary reticulosis is reported. The evolution of a single cellular clone presenting with progressive change of the morphological features of the leukemic cells towards more anaplastic elements endowed with prominent phagocytic properties is suggested on the basis of both cytochemical and chromosomal data. The histiocytic nature of the malignant proliferating cells and platelet phagocytosis has been confirmed by electron microscopic investigation. The main pathogenetic explanations of the evolutionary patterns of the disease are discussed with relation to: a) involvement of a common stem cell giving rise to different proliferative patterns of cells in a multiphasic sequence; b) release of dysplastic platelets and defective erythrocytes with massive sequestration by histioid phagocytic cells; and c) coexistence of two different disorders.