ristocetin and Syndrome

Topics: Adult; Antigens; Blood Coagulation Disorders; Blood Transfusion; Child; Child, Preschool; Factor V Deficiency; Factor VIII; Factor XI Deficiency; Female; Hemophilia A; Hemophilia B; Humans; Male; Pedigree; Ristocetin; Syndrome

Topics: Blood Platelets; Humans; Platelet Aggregation; Ristocetin; Syndrome; Thrombocythemia, Essential; von Willebrand Diseases

Topics: Animals; Antigen-Antibody Complex; Blood Coagulation Factors; Blood Platelet Disorders; Blood Platelets; Blood Proteins; Cell Membrane; Collagen; Complement System Proteins; Cytoplasmic Granules; Factor VIII; Fibrin; gamma-Globulins; Glycoproteins; Humans; Lectins; Platelet Adhesiveness; Platelet Aggregation; Polylysine; Ristocetin; Syndrome; von Willebrand Factor

Acquired von Willebrand syndrome (AVWS) usually mimics von Willebrand disease (VWD) type 1 or 2A. However, in rare cases, the characteristics of other VWD types can predominate in AVWS that might require careful consideration of differential treatment options. The diagnosis and the treatment of a case of type 2B-like AVWS are discussed. Diagnosis of AVWS was ascertained by determining ristocetin cofactor activity, ristocetin-induced platelet aggregation, von Willebrand factor antigen, collagen binding and characterization of von Willebrand factor (VWF) multimers. Inhibitor presence was sought through mixing experiments, the Bethesda method, and calculation of the in-vivo recovery and plasma half-life of VWF after administration of factor VIII/VWF concentrate. Mutations in the A1 domain of VWF were ruled out by sequencing of exon 28 of the VWF gene. A 34-year-old male patient, putatively diagnosed with type 2B VWD, and undergoing laparoscopic cholecystectomy, did not respond adequately to perioperative hemostatic treatment with desmopressin and high doses of factor VIII/VWF concentrate, requiring the administration of recombinant activated factor VII. Further diagnostic workup revealed AVWS mimicking type 2B VWD, most likely owing to an autoantibody developed in the course of underlying monoclonal gammopathy of undetermined significance. The presence of AVWS should be considered before a diagnosis of type 2B VWD is made, especially in patients with a history atypical for inherited disease.

Topics: Adult; Autoantibodies; Bleeding Time; Cholecystectomy, Laparoscopic; Collagen; Deamino Arginine Vasopressin; Diagnosis, Differential; Exons; Factor VII; Factor VIII; Humans; Male; Paraproteinemias; Platelet Aggregation; Protein Binding; Recombinant Proteins; Ristocetin; Sequence Analysis; Syndrome; von Willebrand Disease, Type 2; von Willebrand Factor

Sebastian syndrome is characterized by enlarged platelets and Döhle-like body leukocyte inclusions. This syndrome is an MYH-9-related disease, a group that also includes May-Hegglin anomaly and Fechtner syndrome. The differential diagnosis of the MYH-9 diseases requires ultrastructural studies. Certain in vitro aggregation responses may be abnormal in these conditions.. A 6-month-old boy presented with macrothrombocytopenia but no overt bleeding tendency. Giant platelets and Döhle-like body leukocyte inclusions were present in blood smears from both the patient and his mother. Electron microscopy confirmed ultrastructural features consistent with Sebastian syndrome. Platelet aggregation studies were normal except for an impaired response to the agonist ristocetin.. In this patient peripheral blood analyses and platelet aggregation studies revealed disease features shared with the Bernard-Soulier syndrome, but this syndrome was excluded by cellsurface glycoprotein analysis.

Topics: Bernard-Soulier Syndrome; Blood Platelets; Child, Preschool; Diagnosis, Differential; Humans; Male; Microscopy, Electron; Platelet Aggregation; Ristocetin; Syndrome; Thrombocytopenia

Patient B.G. is a 29-yr-old female with a lifelong bleeding disorder characterized clinically by a highly increased bleeding time, menorrhagias, long-lasting bleeding after cuts and tooth extractions and large post-traumatic haematomas. Her coagulation tests were within normal range, platelet count was 140,000-160,000 per microliters, but platelet function was impaired as demonstrated by the absence of collagen-induced aggregation, although no abnormalities were detected in aggregation response to ADP and ristocetin. Morphologically her platelets were characterized by gigantic size-average profile area was about 2.5 times higher than that of control donors, and severe deficiency of alpha-granules-only 16% of their number in control donors. These features taken together indicated the diagnosis of grey platelet syndrome. As has been shown by quantitative immunoblotting, patient's platelets contained small amounts of alpha-granule membrane protein P-selectin-about 15% of that in control donors. The content of plasma membrane glycoproteins IIb-IIIa and Ib was not reduced, suggesting the specific deficiency of alpha-granule membrane protein. Thus, B.G. is the second patient described in the literature (see also Lages et al, J Clin Invest 1991: 87: 919-929) with combined deficiency of alpha-granules and P-selectin.

Topics: Adenosine Diphosphate; Adult; Bleeding Time; Blood Platelet Disorders; Blood Platelets; Cytoplasmic Granules; Female; Humans; Microscopy, Electron; P-Selectin; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Platelet Membrane Glycoproteins; Ristocetin; Syndrome

Human Factor VIII desialylated by treatment with Vibrio cholerae neuraminidase (ASVIII) aggregated human platelets in the absence of ristocetin in platelet-rich plasma and, to a lesser extent, in washed platelet suspensions. Aggregation is accompanied by thromboxane formation and is completely inhibited by EDTA. Aspirin blocks the second phase of aggregation and abolishes thromboxane production. Subaggregating doses of ASVIII and of either ADP, epinephrine, or collagen produce prompt and complete platelet aggregation. Bernard-Soulier syndrome platelets either did not aggregate with ASVIII (Two cases) or showed markedly decreased aggregation (one cases). Factor VIII complex was prepared from the plasma of two patients with variant von Willebrand's disease (sialic acid content 142 and 75 nmol/mg, respectively); neither protein generated platelet-aggregating activity upon desialylation. [3H]ASVIII binds rapidly to platelets and 37 degrees C, while tritiated, fully sialylated factor VIII binds to a negligible extent. As little as 1--2 micrograms ASVIII bound/10(9) platelets is capable of inducing platelet aggregation. ASVIII may be a useful tool for investigating platelet-Factor VIII interactions in the absence of ristocetin. Furthermore, desialylated Factor VIII might play a physiologic role in Factor VIII-mediated platelet reactions in vivo.

Topics: Asialoglycoproteins; Blood Platelets; Factor VIII; Humans; Platelet Aggregation; Protein Binding; Purpura, Thrombocytopenic; Ristocetin; Sialic Acids; Structure-Activity Relationship; Syndrome

We have studied the binding of Factor VIII/Willebrand factor (FVIII/WF) to the platelets of ten normal donors, five patients with Bernard-Soulier syndrome (BSS), three clinically normal patients heterozygous for BSS (BSS hetero), and three with Glanzmann's thrombasthenia (GT). The amount of 125I-FVIII/WF bound to the platelets was measured in the presence or absence of ristocetin, the results expressed as percentage of total radioactivity added. The time course of 125I-FVIII/WF showed that maximum binding to the platelets was observed at 30 min, and then a plateau was reached. The binding was ristocetin-dependent and was relative to the concentration of ristocetin added. At a final concentration of 0.5 mg/ml of ristocetin, specific binding to the normal platelets was 30.9 +/- 2.5 %; at 1.0 mg/Ml, specific binding was 34.7 +/- 3.2% in the normal donors. In the five BSS patients lacking platelet membrane Glycoprotein 1 (GPI), reduced binding of 125I-FVII/WF was observed. At a final concentration of 1 mg/ml of ristocetin, the mean value of the binding was 13.7 % (11.5 % -14.8 %); at a final concentration of 0.5 mg/ml of ristocetin, the mean value decreased to 5.6 % (2.9 %-7.2 %). In the three BSS hetero patients, binding was near normal, although there were reduced amounts of platelet membrane GPI. Binding was slightly decreased in the three thrombasthenic patients lacking GP IIb/IIIa.

Topics: Binding Sites; Blood Coagulation Factors; Blood Platelet Disorders; Blood Platelets; Factor VIII; Humans; Ristocetin; Syndrome; von Willebrand Factor

Topics: Adult; Albinism; Factor VIII; Female; Hemorrhage; Hemorrhagic Disorders; Humans; Platelet Aggregation; Postoperative Complications; Ristocetin; Syndrome

Ristocetin will induce the agglutination of platelets in the presence of von Willebrand factor. In previous studies, an electrostatic mechanism was proposed for this phenomenon wherein first the platelet's surface charge is reduced by the binding of ristocetin and then the von Willebrand factor acts as a bridge between platelets. To test this hypothesis, the effects of ristocetin and von Willebrand factor, singly and together, on the electrophoretic mobility of normal, trypsinized, and Bernard-Soulier platelets was measured. Ristocetin alone, at concentrations of 0.5 mg/ml or more, produced a statistically significant reduction in the electrophoretic mobility of fresh or fixed platelets. Control experiments showed that the reduction was not due to changes in the ionic milieu of the solution. Therefore, the decrease in platelet mobility is evidence for binding of ristocetin to the platelet surface. Bernard-Soulier and trypsinized platelets also had reductions in mobility with ristocetin, suggesting that ristocetin binds to the platelet at sites other than the binding site for von Willebrand factor. The presence of plasma from a patient with von Willebrand's disease did not alter the reduction in mobility of normal platelets by ristocetin. However, the reduction was markedly enhanced in the presence of normal plasma. This enhancement did not occur with Bernard-Soulier platelets and was inhibited by anti-Factor VIII/von Willebrand factor antiserum or trypsinization of the platelets. Thus, the enhanced reduction appears to be associated with the binding of von Willebrand factor to the platelet surface. These studies indicate that platelets undergo two changes with ristocetin and von Willebrand factor, both of which facilitate agglutination: reduction in net surface charge and binding of von Willebrand factor, a large molecule which can serve as a bridge between platelets. In parallel studies, bovine von Willebrand factor, without ristocetin, agglutinated and reduced the electrophoretic mobility of normal but not Bernard-Soulier or trypsinized platelets; this indicates a similar mechanism of agglutination.

Topics: Antibodies; Binding Sites; Blood Coagulation Factors; Blood Platelets; Electrophoresis; Humans; Movement; Purpura, Thrombocytopenic; Ristocetin; Syndrome; von Willebrand Factor

Topics: Adenosine Diphosphate; Antigen-Antibody Reactions; Aorta; Blood Platelets; Endothelium; Factor VIII; Glycoproteins; Humans; Isoantibodies; Platelet Adhesiveness; Platelet Aggregation; Purpura, Thrombocytopenic; Ristocetin; Syndrome

The authors have examined 8 cases with Hermansky-Pudlak syndrome in whom besides the usual abnormalities of abnormal aggregation with collagen, absence of second wave of aggregation, reduction of the 5-HT uptake, presence of 5-HIAA in the platelets, two new abnormalities are described: the presence of a large amount of an unidentified metabolite after 5-HT incorporation which differs from 5-HT and 5 hydroxytryptophol and an abnormal incorporation of labelled glycerol in the triglycerides. Correlation between abnormal lipid metabolism and defective 5-HT incorporation is discussed.

Topics: Adenosine Diphosphate; Albinism; Bone Marrow; Bone Marrow Cells; Clot Retraction; Collagen; Cytoplasmic Granules; Epinephrine; Glycerol; Hemorrhagic Disorders; Humans; Macrophages; Platelet Aggregation; Ristocetin; Serotonin; Syndrome; Triglycerides

Topics: Adenosine Diphosphate; Adolescent; Factor VIII; Female; Humans; Platelet Aggregation; Purpura, Thrombocytopenic; Ristocetin; Syndrome

The antibiotic ristocetin only aggregates platelets in the presence of plasma von Willebrand factor. Platelets from patients with Bernard-Soulier syndrome do not aggregate upon addition of ristocetin although, in contrast to von Willebrand's disease, plasma levels of factor VIII complex (factor VIII clotting activity, von Willebrand factor activity, and von Willebrand antigen) are normal. The membrane surface of normal platelets was modified and compared to the surface of platelets from a patient with Bernard-Soulier syndrome in an attempt to identify the receptor involved in von Willebrand factor-ristocetin-induced aggregation. After the incubation of washed normal platelets with a preparation of ristocetin previously shown to contain a proteolytic contaminant, the aggregation response is significantly decreased on addition or normal plasma. Analaysis by gel electrophoresis of such platelets when stained for carbohydrate revealed a decrease in the relative amounts of membrane glycopro-eins. Chymotrypsin-treated normal platelets had less membrane glycoproteins in addition to giving a reduced aggregation response in ristocetin-induced aggregation. Staining of gels for protein and carbohydrate indicated that there was an extensive change in the surface of Bernard-Soulier platelets, whereas those from patients with von Willebrand's disease appeared the same as normal. Platelets from patients were labeled by the lactoperoxidase iodination technique. Not only was the relative intensity of staining of platelet-specific proteins and glycoproteins changed in Bernard-Soulier platelets, but the iodination of the glycoproteins on the membrane surface relative to other membrane constituents was lower. In contrast, platelets from patients with von Willebrand's disease showed a normal exposure of membrane components. These data suggest therefore that membrane glycoproteins may play a functional role in ristocetin-induced aggregation.

Topics: Binding Sites; Blood Platelets; Cell Membrane; Glycoproteins; Humans; Peptide Hydrolases; Platelet Aggregation; Purpura, Thrombocytopenic; Ristocetin; Syndrome; von Willebrand Diseases; von Willebrand Factor

Bernard-Soulier syndrome is a rare constitutional thrombopathy, the main clinical feature is a bleeding tendency which is variable. The long bleeding time, in spite of a normal or little decreased platelet count, has been recently explained: the giant platelets have a defective adhesion to subendothelium. This abnormal adhesion could be related with an abnormal pattern of platelet membrane glycoproteins. Interactions between vessel wall, von Willebrand's factor and platelets are discussed.

Topics: Adenosine Diphosphate; Blood Coagulation Factors; Blood Platelets; Cell Membrane; Cell Survival; Collagen; Factor VIII; Factor XI; Glycoproteins; Humans; Platelet Adhesiveness; Platelet Aggregation; Purpura, Thrombocytopenic; Ristocetin; Serotonin; Sialic Acids; Syndrome; Thromboplastin; von Willebrand Factor

Five patients with an original diagnosis of von Willebrand's disease are described because of their levels of factor VIII related protein, Ristocetin-induced platelet aggregation and/or family studies differed from the main group of patients with classical von Willebrand's disease. Two had normal levels of factor VIII related protein with reduced Ristocetin aggregation when this was tested in platelet rich plasma. In one, however, this was due to a plasma defect and in the other to a platelet abnormality. After cryoprecipitate infusion all abnormal tests were corrected in both these patients. The first patient, however, failed to show a secondary rise of factor VIII whereas the second showed a secondary rise of both factor VIII and of factor VIII related protein. The other three cases, who were all very severely affected, have been separated from the main group as none of their families was segregating for classical von Willebrand's disease. It is suggested that the term von Willebrand's disease should be confined to those patients who have reduced factor VIII related protein and Ristocetin aggregation, and that von Willebrand's syndrome should be used for the various sub-groups that are emerging.

Topics: Adult; Factor VIII; Female; Humans; Middle Aged; Pedigree; Platelet Aggregation; Ristocetin; Syndrome; von Willebrand Diseases

Topics: Adolescent; Animals; Blood Cell Count; Blood Coagulation; Blood Coagulation Tests; Blood Platelets; Cattle; Chemical Precipitation; Child; Chromatography, Gel; Endothelium; Factor VIII; Fibrinogen; Hemostasis; Humans; Male; Platelet Adhesiveness; Purpura, Thrombocytopenic; Ristocetin; Syndrome

Topics: Animals; Antigens; Blood Coagulation Disorders; Blood Platelets; Factor VIII; Humans; Immunoelectrophoresis; Purpura, Thrombocytopenic; Rabbits; Ristocetin; Syndrome; von Willebrand Diseases

The platelets of three patients with the hereditary giant platelet syndrome of Bernard and Soulier failed to aggregate in response to either ristocetin or bovine fibrinogen. The results of aggregation experiments using mixtures of platelets and plasma suggest that a reaction between a plasma factor deficient in von Willebrand's disease and a platelet component lacking in our patients, and leading to platelet aggregation independently of adenosine diphosphate (ADP), is essential for normal haemostasis.

Topics: Adenosine Diphosphate; Adolescent; Blood Platelet Disorders; Child; Collagen; Female; Fibrinogen; Hemorrhage; Humans; Plasma; Platelet Adhesiveness; Prothrombin; Purpura, Thrombocytopenic; Ristocetin; Syndrome; Thrombin; von Willebrand Diseases