Novel function for beta 1 integrins in keratinocyte cell-cell interactions.

We have examined the expression, localization, and function of beta 1 integrins on cultured human epidermal keratinocytes using polyclonal and monoclonal antibodies against the beta 1, alpha 2, alpha 3, and alpha 5 integrin subunits. The beta 1 polypeptide, common to all class 1 integrins, was localized primarily in areas of cell-cell contacts of cultured keratinocytes, as were alpha 2 and alpha 3 polypeptides, suggesting a possible role in cell-cell adhesion for these integrin polypeptides. In contrast, the fibronectin receptor alpha 5 subunit showed no such accumulations in regions of cell-cell contact but was more diffusely distributed in the keratinocyte plasma membrane, consistent with the absence of fibronectin at cell-cell contact sites. Colonies of cultured keratinocytes could be dissociated by treatment with monoclonal antibody specific to the beta 1 polypeptide. Such dissociation of cell-cell contacts also occurred under conditions where the monoclonal antibody had no effect on cell-substrate adhesion. Therefore, beta 1 integrin-dependent cell-cell adhesion can be inhibited without affecting other cell-adhesive interactions. Antibody treatment of keratinocytes maintained in either low (0.15 mM) or high (1.2 mM) CaCl2 also resulted in the loss of organization of intracellular F-actin filaments and beta 1 integrins, even when the anti-beta 1 monoclonal antibody had no dissociating effect on keratinocyte colonies at the higher calcium concentration. Our results indicate that beta 1 integrins play roles in the maintenance of cell-cell contacts between keratinocytes and in the organization of intracellular microfilaments. They suggest that in epithelial cells integrins can function in cell-cell interactions as well as in cell-substrate adhesion.

Carbohydrate deficiency of the factor VIII/von Willebrand factor Protein in von Willebrand's disease variants.

Study of the normal human factor VIII/von Willebrand factor reveals a macromolecular glycoprotein composed of apparently identical subunits. This purified glycoprotein has procoagulant, antigen, and von Willebrand factor activities. In three patients with a variant of the von Willebrand's disease syndrome, their factor VIII/von Willebrand factor protein was present in normal amounts and had normal procoagulant and antigen activities; however, this protein was deficient in both carbohydrate and von Willebrand factor activity. The carbohydrate portion of the factor VIII/von Willebrand factor glycoprotein is of major importance in its interactions with platelets or the blood vessel wall, or both.

Factor VIII/von Willebrand factor protein. Galactose a cryptic determinant of von Willebrand factor activity.

The normal Factor VIII/von Willebrand factor protein has the ability to agglutinate or aggregate normal platelets in the presence of ristocetin (von Willebrand factor activity). Removal of greater than 95% of the sialic acid from this protein by neuraminidase did not affect the von Willebrand factor or procoagulant activity. However, oxidation of the penultimate galactose of the asialo Factor VIII/von Willebrand factor protein with galactose oxidase resulted in a progressive loss of von Willebrand factor activity with no effect on procoagulant activity. Reduction of the 6-aldehydo intermediate by potassium borohydride caused full regeneration of von Willebrand factor activity. These studies confirm the identification of the intact penultimate galactose moiety as a critical determinant of von Willebrand factor activity.

Studies on the mechanism of ristocetin-induced platelet agglutination. Effects of structural modification of ristocetin and vancomycin.

The mechanism by which ristocetin induces platelet agglutination in the presence of the von Willebrand factor was studied by chemically altering ristocetin and a similar antibiotic, vancomycin, by reaction with a water-soluble carbodiimide in the presence of glycine methyl ester at pH 4.75. Altering ristocetin's phenolic groups (which are thought to be important in its peptide-binding properties) resulted in a loss of both platelet-agglutinating and antibiotic activities. Restoring the phenolic groups with hydroxylamine restored both activities. Vancomycin has antibiotic and peptide-binding properties similar to ristocetin's, but differs structurally in having a free carboxyl group and thus a less positive charge at neutral pH. It does not induce platelet agglutination and actually inhibits ristocetin-induced agglutination. Reacting vancomycin with the water-soluble carbodiimide resulted in alteration of phenolic groups and permanent conversion of the carboxyl to a neutral derivative. Restoring the phenolic groups with hydroxylamine (but leaving the carboxyl neutralized) produced a compound with charge properties similar to ristocetin's which induced platelet agglutination as ristocetin does. These data suggest both a binding requirement (mediated through phenolic groups) and a strong positive charge requirement for ristocetin-induced agglutination. The data are consistent with a model wherein positively charged ristocetin binds, via its phenolic groups, to sites on the platelet surface and reduces the platelet's negative charge. This could reduce the electrostatic repulsion between platelets and/or between platelets and the negatively charged von Willebrand factor, and permit the macromolecular von Willebrand factor to cause agglutination by bridging between platelets.

Identification of the thrombin receptor on human platelets by chemical crosslinking.

To identify the molecular site of thrombin binding to the platelet membrane, we covalently linked 125I-thrombin to platelets by using the bifunctional chemical cross-linking agents disuccinimidyl suberate and dithiobis(succinimidyl propionate). The proteins cross-linked to 125I-thrombin by this method were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and followed by autoradiography. Two radiolabeled thrombin complexes were identified, a major species of Mr approximately 200,000 and a minor one of Mr approximately 400,000. Hirudin prevented the formation of both complexes. The radioactivity of the approximately 200,000-Mr complex was always 7-10-fold greater than the radioactivity of the approximately 400,000-Mr complex regardless of the thrombin concentration to which the platelets were exposed (0.1-29 nM). Although 125I-thrombin complexes generated with thrombasthenic platelets (lacking glycoprotein IIb/IIIa) were indistinguishable from normal, no complexes appeared when Bernard-Soulier platelets (lacking glycoprotein Ib [GPIb]) were used. Complex formation was blocked by rabbit antiglycocalicin antiserum, but not by the monoclonal antibody 6D1, which is directed against the site on GPIb where von Willebrand factor (vWf) binds in the presence of ristocetin. Although cross-linking studies suggested that vWf might partially inhibit thrombin binding to platelets, this was not confirmed by equilibrium binding studies in the presence of vWf and ristocetin. The data suggest, therefore, that at all thrombin concentrations binding occurs at the same membrane site, despite evidence from equilibrium studies for high and low affinity classes of receptors, and that the approximately 400,000-Mr complex is simply a dimer of the approximately 200,000-Mr species. We conclude that the membrane site to which thrombin binds is the glycocalicin portion of platelet GPIb at a site remote from the point of ristocetin-dependent vWf binding.

Studies of the human factor VIII/von Willebrand factor protein. III. Qualitative defects in von Willebrand's disease.

The Factor VIII/von Willebrand factor protein was characterized in two unrelated patients with von Willebrand's disease in whom procoagulant and Factor VIII/von Willebrand factor antigen levels were normal. In both patients evidence of an abnormal protein was observed on crossed antigen-antibody electrophoresis. In one patient the Factor VIII/von Willebrand factor protein eluted from Sepharose 4B in a position and distribution identical to normal with normal levels of procoagulant activity and antigen. However, the partially purified Factor VIII/von Willebrand factor protein had markedly reduced von Willebrand factor activity in a ristocetin assay. In the second patient the peak of Factor VIII/von Willebrand factor protein, antigen, and procoagulant activity eluted from a Sepharose 4B column with an estimated molecular weight of approximately half that of normal. This protein had no von Willebrand factor activity. In both patients the reduced Factor VIII/von Willebrand factor protein subunit was indistinguishable from normal on polyacrylamide gel electrophoresis. These studies indicate that in some patients with von Willebrand's disease there is a qualitative defect of the Factor VII/von Willebrand factor protein; the total amount of protein, antigen, and procoagulant activity are normal while the von Willebrand factor activity is deficient.

Studies on the purification and characterization of human factor 8.

Factor VIII (antihemophilic globulin) has been prepared from Hyland method IV AHG and cryoprecipitate using limited chymotryptic digestion followed by Sepharose gel filtration. The activity of factor VIII is unaffected by the digestion procedure, while fibrinogen in converted to large noncoagulable fragments. The purified factor VIII has been found to be a macromolecular glycoprotein with a major subunit of 240,000, as shown by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Carbohydrate analysis of factor VIII gave values of 1% sialic acid, 2.8% hexosamine, and 1-2% hexose (mannose, galactose, and fucose). The lipid content was found to be less than 5% of the protein content, and included no detectable phospholipid. The amino acid content is also reported. Immunoelectrophoretic analysis using rabbit antibody to purified factor VIII produced a single precipitin line. The chymotrypsin digestion step facilitates the preparation of factor VIII by reducing the viscosity of fibrinogen in the crude starting material, thereby increasing fivefold the quantity of material which can be processed at one time. It also improves markedly the resolution between factor VIII and fibrinogen on gel filtration.

Fibrinogen Bethesda: a congenital dysfibrinogenemia with delayed fibrinopeptide release.

A dysfibrinogenemia (fibrinogen Bethesda) was detected in a 9 yr old male of Mexican-English extraction who had a lifelong history of mild bleeding diathesis. The prothrombin and partial thromboplastin times were moderately prolonged; the thrombin and Reptilase times were markedly prolonged. The plasma fibrinogen level was normal by conventional methods but was markedly reduced by the Clauss method. Results of all other tests for clotting factors, fibrinolysis, antithrombin levels, clot stabilization, and fibrin(ogen) degradation products were normal. The patient's plasma and fibrinogen inhibited the clotting of normal plasma or fibrinogen by thrombin. Family studies revealed that the propositus' mother and two siblings exhibited these abnormalities to a lesser degree and indicated an autosomal dominant inheritance. Fibrinogen Bethesda was similar to normal fibrinogen in the following respects: metabolic turnover time (measured in the propositus' mother); immunodiffusion, ultracentrifugal, electrophoretic (on cellulose acetate or polyacrylamide gel), and chromatographic (on DEAE-cellulose) characteristics; sialic acid content; and aggregation of fibrin monomers. By contrast, fibrinogen Bethesda gave an abnormal immunoelectrophoretic pattern especially when whole plasma (as opposed to purified fibrinogen) was examined, and it showed a pronounced decrease in the rate of fibrinopeptide release by thrombin. This decrease, which was shown to involve both fibrinopeptides A and B, distinguishes fibrinogen Bethesda from previously reported dysfibrinogenemias.

Arginine-glycine-aspartic acid- and fibrinogen gamma-chain carboxyterminal peptides inhibit platelet adherence to arterial subendothelium at high wall shear rates. An effect dissociable from interference with adhesive protein binding.

Arg-Gly-Asp (RGD)- and fibrinogen gamma-chain carboxyterminal (GQQHHLGGAKQAGDV) peptides inhibit fibrinogen, fibronectin (Fn), vitronectin, and von Willebrand factor (vWF) binding to the platelet glycoprotein IIb-IIIa complex (GP IIb-IIIa). GP IIb-IIIa, vWF, and Fn are essential for normal platelet adherence to subendothelium. We added peptides to normal citrated whole blood before perfusion over human umbilical artery subendothelium and evaluated platelet adherence morphometrically at high (2,600 s-1) and low (800 s-1) wall shear rates. We also examined the effects of the peptides on platelet adhesion to collagen in a static system. At the high wall shear rate, RGDS and GQQHHLGGAKQAGDV caused dose-dependent reduction in the surface coverage with spread and adherent platelets. Amino acid transposition and conservative substitutions of RGD peptides and the AGDV peptide significantly inhibited platelet adherence at 2,600 s-1. By contrast, the modified RGD peptides and AGDV do not affect adhesive protein binding to platelets. None of the native or modified RGD- or fibrinogen gamma-chain peptides significantly inhibited either platelet adherence to subendothelium at 800 s-1 or platelet adhesion to collagen. Our findings demonstrate that peptides that interfere with adhesive protein binding to GP IIb-IIIa inhibit platelet adherence to vascular subendothelium with flowing blood only at high wall shear rates. Platelet adherence to subendothelium at high wall shear rates appears to be mediated by different recognition specificities from those required for fluid-phase adhesive protein binding or static platelet adhesion.

The molecular defect in type IIB von Willebrand disease. Identification of four potential missense mutations within the putative GpIb binding domain.

Type IIB von Willebrand Disease (vWD) is characterized by the selective loss of large von Willebrand Factor (vWF) multimers from plasma, presumably due to their increased reactivity with platelets and subsequent clearance from the circulation. Using the PCR, one of a panel of four potential missense mutations was identified in each of the 14 patients studied from 11 unrelated families. None of these substitutions was encountered in a large panel of normal DNAs. These changes all represent C----T transitions at CpG dinucleotides, proposed "hot spots" for mutation in the human genome. The four resulting amino acid substitutions, Arg543----Trp, Arg545----Cys, Val553----Met, and Arg578----Gln, are all clustered within the GpIb binding domain of vWF. Disruption of this latter functional domain may explain the pathogenesis of Type IIB vWD. By sequence polymorphism analysis, the Arg543----Trp substitution was shown to have occurred as at least two independent mutational events. This latter observation, along with the identification of mutations in all 14 patients studied and their localization to the GpIb binding domain, all strongly suggest that these substitutions represent the authentic defects responsible for Type IIB vWD. This panel of mutations may provide a useful diagnostic tool for the majority of patients with Type IIB vWD.

Mechanisms underlying the morning increase in platelet aggregation: a flow cytometry study.

OBJECTIVES: Mechanisms underlying the morning increase in platelet aggregation produced by arising and assuming the upright posture were studied by examining 1) the expression on the platelet surface of activation-dependent markers; 2) platelet aggregation in whole blood; and 3) hematologic factors likely to influence aggregation. BACKGROUND: The morning increase in thrombotic cardiovascular events has been attributed, in part, to the morning surge in platelet aggregability, but its mechanisms are poorly understood. METHODS: Expression of seven platelet surface antigens (including P-selectin, activated GPIIb,IIIa and GPIb-IX), whole-blood platelet aggregation, platelet count and hematocrit were measured before and after arising in 17 normal volunteers. The fibrinolytic variables, tissue-type plasminogen activator, plasminogen activator inhibitor 1 and catecholamine levels were also measured. RESULTS: On arising and standing, platelet aggregation increased by 71% (p < 0.01) and 27% (p < 0.03) in response to collagen and adenosine diphosphate, respectively. However, there was no change in any of the activation-dependent platelet surface markers. Whole-blood platelet count and hematocrit increased by 15% and 7% (both p < 0.0001), respectively. Norepinephrine and epinephrine levels increased by 189% (p < 0.0001) and 130% (p < 0.01), respectively. Tissue-type plasminogen activator antigen increased (31%, p < 0.01), but there was no significant increase in plasminogen activator inhibitor 1, suggesting an overall increase in fibrinolysis on standing. Prothrombin fragment 1.2 increased by 28% (p < 0.02), indicating a small increase in thrombin generation. The increases in hematocrit and platelet count that occurred on standing were carefully mimicked in vitro and resulted in a 115% (p < 0.05) increase in platelet aggregation in response to adenosine diphosphate. CONCLUSIONS: These data demonstrate that the morning increase in platelet aggregation is not accompanied by expression of activation-dependent platelet surface receptors and suggest that the increase in whole-blood aggregation may be primarily due to the increases in catecholamine levels, platelet count and hemoconcentration.

Hypergranular promyelocytic leukemia: correlation between morphology and chromosomal translocations including t(15;17) and t(11;17).

The FAB group has reviewed 32 cases of promyelocytic leukemia and variant forms. By utilizing published criteria the ability to make a correct diagnosis by morphology with molecular genetic confirmation and to eliminate cases that did not have the PML/RARalpha rearrangement was excellent.

Treatment of polyneuropathy in Waldenström's macroglobulinemia: role of paraproteinemia and immunologic studies.

A patient with polyneuropathy due to Waldenström's macroglobulinemia (WM) was treated successfully with chlorambucil and prednisone. Before therapy, 60% of peripheral lymphocytes were B cells, the nerve had IgM-bearing B-cell infiltrates, and the circulating IgM had antibody-binding activity to autologous and homologous nerves. Neurologic improvement, sustained for 4 years, began 3 months after therapy and coincided with the return to normal of bone marrow and circulating B cells. Binding of IgM to autologous and homologous nerves persisted after therapy, suggesting that not the IgM alone but other B-cell factors, possibly complexed to IgM, may have been responsible for the nerve damage.

Blast crisis of chronic granulocytic leukemia. Morphologic variants and therapeutic implications.

Chronic granulocytic leukemia (CGL) terminates in a disease similar to acute leukemia. Except for a study indicating an increased response rate to the drugs, vincristine and prednisone, therapy of this terminal phase has been universally disappointing. We have studied the bone marrows and clinical courses of 67 patients in the terminal phase of CGL to discern if any parameters were associated with an increased response rate or survival. The results of this study indicate that patients who have a lymphoblastic morphology or hypodiploid cytogenetics in the terminal phase respond better to treatment with the combination of vincristine and prednisone than those with myeloblastic morphology or hyperdiploid cytogenetics. Response rate and survival are significantly increased in those with lymphoblastic morphology. Recognition of the heterogeneity of the terminal phase of CGL may dictate specific therapeutic modalities.

Plasma and platelet von Willebrand factor defects in uremia.

PURPOSE: Several mechanisms have been proposed to explain the prolonged bleeding times and clinical bleeding in chronic renal failure. Recent evidence has implicated an abnormality in the structure or function of the von Willebrand factor or in its interaction with uremic platelets. We investigated this factor in 11 patients with chronic renal failure. PATIENTS AND METHODS: Blood samples for cell counts, chemistries, and coagulation studies were obtained from 11 patients with chronic renal failure and prolonged bleeding times. Concentrations of von Willebrand factor antigen and ristocetin cofactor activity were determined in plasma and platelets. Multimeric analysis of von Willebrand factor in plasma and platelets was conducted. In eight cases, the platelets of uremic patients were purified, and the thrombin- and ristocetin-induced binding of normal von Willebrand factor to these platelets was examined. RESULTS: The mean plasma von Willebrand factor antigen and activity (ristocetin cofactor assay) were elevated 2.77 mu/ml and 1.88 mu/ml, respectively (normal, 1.01 mu/ml and 1.07 mu/ml, respectively). The ratio of activity to antigen in uremic plasma was 0.67 (normal, 1.05). The mean platelet von Willebrand factor antigen and activity in the uremic patients was decreased (0.26 and 0.50 mu/10(9) platelets, respectively) compared with normal patients (0.46 and 0.93 mu/10(9) platelets, respectively). The oligomeric structure of the uremic plasma von Willebrand factor lacked the largest multimers. Collection of the blood for analysis in several protease inhibitors and/or EDTA did not change the multimeric structure. The von Willebrand factor multimeric structure of platelets from uremic patients was normal. The ristocetin-induced platelet aggregation of the uremic platelet-rich plasma was decreased compared with normal plasma samples. Thrombin and ristocetin-induced binding of normal von Willebrand factor to uremic patients' platelets was indistinguishable from the binding to normal platelets. CONCLUSION: These data suggest that the uremic platelet-binding sites for von Willebrand factor are intact and that the defect in ristocetin-induced platelet aggregation is most likely plasmatic in nature. At least one plasmatic defect was the observed reduction or absence of the largest plasma von Willebrand factor multimer in uremic patients. The platelet von Willebrand content was significantly decreased. These defects may play a role in the prolonged bleeding time and the clinical bleeding observed in patients with uremia.

American Burkitt's lymphoma: a clinicopathologic study of 30 cases. II. Pathologic correlations.

Thirty cases of malignant lymphoma, undifferentiated, Burkitt's type are reviewed. An older median age and a predominance of presentation in abdominal and pelvic sites rather than in the jaw distinguishes this series of American patients from those reported from endemic regions in Africa. Bone marrow involvement invariably consisted of massive infiltration recognizable in smear, clot and biopsy preparations. Involvement of the central nervous system or bone marrow was always associated with short survival. In all eight long-term survivors lymphoma was apparently confined to a single site at presentation. At autopsy, the most consistent finding was widespread multiorgan involvement without predilection for lymphoreticular structures. The histologic appearance of the tumor changed after chemotherapy, varying from diffuse necrosis within 48 hours of initial therapy to extreme pleomorphism of tumor cells after 9 months of therapy. In one patient, there was almost complete absence of lymphoma at autopsy in an organ site shown clinically to have been extensively involved by tumor prior to treatment. The diagnostic and therapeutic implications of these findings are discussed.

Hematologic manifestations of systemic mast cell disease: a prospective study of laboratory and morphologic features and their relation to prognosis.

PURPOSE: Systemic mast cell disease (SMCD) follows an indolent course in most patients, but a significant number of patients die of neoplastic hematologic disorders. Reviews of the literature and retrospective studies in a single institution have defined features that may be associated with a poor prognosis, but prospective studies have been lacking. Therefore, we prospectively analyzed the relationship between clinical, laboratory, and hematopathologic findings and clinical outcome in a series of 46 patients with mast cell disease. This analysis was employed to both define clinically useful prognostic variables and describe the histologic evolution of bone marrow mast cell infiltration and its relationship to hematologic neoplasia. PATIENTS AND METHODS: Forty-six adult patients were referred to the National Institutes of Health (NIH) with clinical and/or pathologic evidence of mast cell proliferation. All patients had bone marrow examinations, and 10 patients underwent serial bone marrow biopsies. The diagnosis of SMCD required pathologic documentation of bone marrow mast cell infiltrates. The patients were followed for up to 13 years at the NIH (up to 30 years after the initial pathologic diagnosis of mast cell disease). Statistical analysis defined the correlation between variables and the presence of diagnostic bone marrow lesions. The Kaplan-Meier method was used to construct survival curves, and the effects of various variables on the survival time were examined. RESULTS: Thirty-two of 46 patients (74%) had a bone marrow biopsy diagnostic for SMCD. The remaining 14 patients were considered to have cutaneous mast cell disease (CMCD). Univariate analysis showed that hepatosplenomegaly, alkaline phosphatase level, absolute lymphocyte count, and age at onset of symptoms were positively correlated with SMCD, whereas hemoglobin level was negatively associated with diagnostic bone marrow lesions. With multivariate analysis, only hemoglobin and absolute lymphocyte count remained as significant independent predictors of bone marrow findings. No CMCD patient died or had significant clinical deterioration in the 1- to 30-year period of follow-up (median = 8.5 years), whereas 10 of 32 SMCD patients (31%) died from 1 to 22 years after diagnosis (median = 2.5 years) (p less than 0.0001). Univariate analysis revealed the following variables as significantly increasing the risk of death in patients with SMCD: later onset of symptoms, absence of cutaneous mastocytosis, thrombocytopenia, elevated lactate dehydrogenase (LDH) level, anemia, bone marrow hypercellularity, qualitative peripheral blood smear abnormalities, elevated alkaline phosphatase level, and hepatosplenomegaly. Multivariate analysis showed that only the age at onset of symptoms and LDH levels were significant independent predictors of survival. Eight of the 10 SMCD patients who died had myeloproliferative or myelodysplastic syndromes or acute nonlymphocytic leukemia. CONCLUSION: Our prospective study has defined a number of important variables in patients with clinical evidence of mast cell proliferation that can predict both the presence of SMCD and the likelihood of fatal disease. Since recent evidence suggests that mast cells derive from a bone marrow hematopoietic progenitor, SMCD may represent a myeloproliferative condition with the propensity to evolve into a neoplastic granulocytic disorder in a significant minority of patients.

American Burkitt's lymphoma: a clinicopathologic study of 30 cases. I. Clinical factors relating to prolonged survival.

The presenting clinical characteristics and the results of therapy in 30 cases of American Burkitt's lymphoma are described. Five patients presented with localized disease. The abdomen was the most frequent site of involvement (19 cases). Serum lactic dehydrogenase (LDH) levels closely correlated with extent of tumor mass. Of the 22 patients treated with large doses of parenteral cyclophosphamide, complete remission was achieved in 13 (59 per cent). Of these only four have had a relapse, all within 12 months of treatment. The remainder are alive, free of disease and have not received any treatment for up to 80 months or more. The site and volume of tumor mass predicted for prolonged survival. None of the six patients with bone marrow or central nervous system involvement remained tumor-free. A complete remission was achieved in 8 of 9 patients with presenting LDH levels of less than 700 IU/ml and they have remained free of disease, whereas only 4 of 13 patients with LDH levels greater than 700 IU/ml had a complete response and 3 of these had a relapse within 12 months. In six cases, the massive tumor regression following chemotherapy was associated with serious metabolid consequences including hyperkalemia (six cases), hypocalcemia, hyperphosphatemia (one case) and lactic acidosis (one case). There were four sudden deaths in less than 48 hours after chemotherapy; two of these were attributable to hyperkalemia. In all cases therw were large tumor masses and/or elevated serum LDH levels.

Abnormal coagulation results in patients with Hodgkin's disease.

Case records of 177 patients admitted with Hodgkin's disease were reviewed to assess the frequency and significance of coagulation abnormalities. Prolongation of the prothrombin time, activated partial thromboplastin time, or thrombin time occurred in 56 patients, 32 percent of all evaluable cases. The most frequent clotting abnormalities involved the prothrombin time, which was increased in 43 patients (24 percent). Prothrombin time prolongation correlated with bulky or advanced disease as defined by stage (p = 0.001), constitutional symptoms (p less than 0.0001), massive mediastinal involvement (p = 0.02), and elevated alkaline phosphatase levels (p less than 0.0001). Abnormal coagulation test results followed the course of disease, normalizing with tumor regression and reappearing during relapse. Despite the surprising incidence of abnormal coagulation results, bleeding complications were reported in only two cases. Patients undergoing invasive procedures in the presence of clotting abnormalities fared no worse than those in whom procedures were cancelled. There is no evidence that complete staging evaluation should be comprised because of these abnormal test values. Extensive hematologic testing revealed no single mechanism to explain the coagulation factor disorders found in Hodgkin's disease.

Heparin enhances endothelial cell von Willebrand factor content by growth factor dependent mechanisms.

Von Willebrand factor (vWf), a multimeric adhesive glycoprotein synthesized, stored, and secreted in megakaryocytes and endothelial cells, is normally found in plasma, platelets and subendothelium. While many substances mediate the release of vWf from endothelial cells, factors that enhance vWf synthesis and partitioning to its regulated pathway are currently unknown. We studied the effect of pharmacologic doses of heparin on the vWf content of endothelial cells. After a lag of 8 h and in the presence of crude or purified growth factor, heparin at doses between 0.25 and 2 U (1.4-11 micrograms)/ml, increased the content of high molecular weight vWf. The increased amounts of vWf were localized to Weibel-Palade bodies and extracellular matrix. Lower molecular weight highly sulfated heparin or heparin-like compounds were most active in growth factor dependent endothelial cell vWf expression. There was no clear importance of polysaccharide sequence or protein core.