Evaluation of a weight-adjusted single-bolus plasminogen activator in patients with myocardial infarction: a double-blind, randomized angiographic trial of lanoteplase versus alteplase.

BACKGROUND: Lanoteplase (nPA) is a rationally designed variant of tissue plasminogen activator with greater fibrinolytic potency and slower plasma clearance than alteplase. METHODS AND RESULTS: InTIME (Intravenous nPA for Treatment of Infarcting Myocardium Early), a multicenter, double-blind, randomized, double-placebo angiographic trial, evaluated the dose-response relationship and safety of single-bolus, weight-adjusted lanoteplase. Patients (n=602) presenting within 6 hours of acute myocardial infarction were randomized and treated with either a single-bolus injection of lanoteplase (15, 30, 60, or 120 kU/kg) or accelerated alteplase. The primary objective was to determine TIMI grade flow at 60 minutes. Angiographic assessments were also performed at 90 minutes and on days 3 to 5. Follow-up was continued for 30 days. Lanoteplase achieved its primary objective, demonstrating a dose-response in TIMI grade 3 flow at 60 minutes (23.6% to 47.1% of subjects, P<0. 001). Similar results were observed at 90 minutes (26.1% to 57.1%, P<0.001). At 90 minutes, coronary patency (TIMI 2 or 3) increased across the dose range up to 83% of subjects at 120 kU/kg lanoteplase compared with 71.4% with alteplase. Thus, at this dose, lanoteplase was superior to alteplase in restoring coronary patency (difference, 12%; 95% CI, 1% to 23%). The early safety experience in this study suggests that lanoteplase was well tolerated at all doses with safety comparable to that of alteplase. CONCLUSIONS: Lanoteplase, a single-bolus, weight-adjusted agent, increased coronary patency at 60 and 90 minutes in a dose-dependent fashion. Coronary patency at 90 minutes was achieved more frequently with 120 kU/kg lanoteplase than alteplase. In this study, safety with lanoteplase and alteplase was comparable. InTIME-II, a worldwide mortality trial, will evaluate efficacy and safety with this promising new agent.

Procoagulant activity of T lymphoblastoid cells in extrinsic and intrinsic coagulation systems.

We have measured the procoagulant activity (PCA) of four T lymphoblastoid cell lines (Jurkat, CEM, HSB-2 and Molt 4) as well as normal peripheral blood T lymphocytes, before and after stimulation with phytohaemagglutinin (PHA), using clotting and amidolytic methods. Of the four cell lines only one, Jurkat, gave enhanced PCA after stimulation with PHA. This activity was shown to be tissue factor-like by its dependence on factor VII in plasma and in an amidolytic assay with purified factors VII and X. Jurkat was also the only one of the four cell lines to secrete interleukin-2. All four cell lines promoted the generation of large amounts of thrombin in platelet-free plasma in glass tubes. This activity was dependent on the presence of plasma factor VIII, and was probably due to phospholipids in the cell membranes. Normal T lymphocytes gave intrinsic PCA in the thrombin generation test which was only 15% of that of the lymphoma cells. These results show that some T lymphocytes can develop PCA in both intrinsic and extrinsic systems and this should be taken into account in studies of the PCA of mixed leukocyte populations.

Detection of kidney reactive antibodies at crossmatch in renal transplant recipients.

We have investigated retrospectively sera from 70 renal allograft recipients for the presence of antibodies binding to a preanastomosis biopsy of the donor kidney by an indirect immunoperoxidase technique. All recipients had a negative T cell lymphocytotoxic crossmatch. A positive immunoperoxidase crossmatch for kidney-reactive antibodies was seen in 13/70 (18.6%) recipients--6 reacting with endothelium, 4 with epithelium, and 3 with both cell types. Neither the presence of these antibodies nor their pattern of staining correlated with recipient graft outcome. Following transplantation endothelial reactive antibodies developed in 15/43 (35%) patients, whereas tubular epithelial antibodies occurred in 5/43 (12%). The antibodies were persistent and accompanied graft failure in 10/14 (71%) patients, while transient antibodies were only associated with graft failure in 2/12 (17%) recipients. Development of lymphocytotoxic antibodies did not correlate with the presence of renal reactive antibodies or eventual graft outcome. Smooth muscle and antinuclear antibodies in recipient sera prior to transplantation were associated with improved graft survival. Eluates of 8/14 rejected grafts confirmed the presence of renal reactive antibodies, with patterns of staining similar to those observed in recipient sera. Antibodies in 7/8 recipients were shown by absorption studies to have HLA class I and/or II specificity, the remaining recipient having proximal tubular brush border antibodies.

Immunochemical characterization of a new platelet specific monoclonal antibody and its use to demonstrate the cytoskeletal association of the platelet glycoprotein IIb-IIIa complex.

We describe the production and characterization of a monoclonal antibody specific for platelets. This antibody reacts strongly with human and primate platelets, but does not recognise human monocytes, polymorphonuclear leucocytes, lymphocytes, erythrocytes, leukaemic nor fibroblast cell lines, nor rodent platelets. Immunoprecipitation studies using radiolabelled platelet membrane proteins showed that the monoclonal antibody binds to the platelet membrane glycoprotein IIb-IIIa complex. Affinity chromatography using immobilized monoclonal antibody allows purification of the antigen, but also co-purifies the cytoskeletal proteins actin and myosin. Our results demonstrate immunochemically that although the GP IIb-IIIa complex is an external structure, it is connected through the cell membrane to the microfilament system.

Varying expression of major histocompatibility complex antigens on human renal endothelium and epithelium.

Pre-anastomosis wedge biopsies from 14 cadaveric donor kidneys were examined for the expression of class I (HLA-ABC) and class II (HLA-DR) antigens in renal tissue. Two monoclonal antibodies to class I antigens and four to class II antigens were used in an indirect immunoperoxidase technique. Consistent expression of both antigens was demonstrated on the surface of glomerular, peritubular capillary and venous endothelial cells. Renal arteries contained only class I antigens. Proximal tubules contained varying amounts of each antigen in their cytoplasm. Sixteen human lymphocytotoxic allo-antisera showed marked variation in their ability to detect HLA antigens on the kidney. The selection of donors for recipients of renal allografts involves the complement-dependent cytotoxicity test and the failure of some lymphocytotoxic antisera to bind to the kidney indicates that some suitable patients may be incorrectly excluded. The use of a binding assay using an immunoperoxidase technique should be included in cross-match techniques particularly for patients who have high levels of circulating cytotoxic antibodies.

Variable localization of blood group antigen in group A kidneys.

The distribution of the blood group A antigen has been examined in 7 Group A kidneys using an indirect immunoperoxidase technique. Monoclonal antibody consistently demonstrated A antigen on the endothelium of all kidneys, particularly peritubular capillary endothelial cells and also the epithelial cells of distal tubules of all but 1 case. Nine hyperimmune anti-A alloantisera gave a variable pattern of staining on different endothelial cells, but no kidney was negative. Epithelial cell staining showed considerable variation both within an individual cell and between adjacent cells. Twenty-six out of 40 alloantisera from normal Group O blood donors failed to bind to endothelial cells of one kidney which was known to show strong expression of A antigen. Absorption was completely achieved using Group A red blood cells but not with a synthetic blood group substance. The variation in reaction intensity using different antisera emphasises that there is variation in antigen expression between cells and indicates the complexity of antibodies directed against the blood group A antigen.