Streptokinase neutralisation titres up to 866 days after intravenous streptokinase for acute myocardial infarction

Antistreptokinase antibodies and the response to thrombolysis with streptokinase in patients with acute ST elevation myocardial infarction

BACKGROUND AND OBJECTIVE

A large number of patients with ST elevation myocardial infarction (STEMI) continue to receive streptokinase (SK) in the developing countries. High levels of antistreptokinase (ASK) antibodies can result in failure of thrombolysis. This study was conducted to assess the presence of ASK antibodies in the general population and its effect on the outcome of thrombolysis with SK.

DESIGN

Prospective observational study.

SETTING

A tertiary care medical institute in Vellore, India.

PATIENTS

148 patients presenting with STEMI undergoing thrombolysis with SK were recruited.

MAIN OUTCOME MEASURES

The response to SK was assessed by reperfusion markers in the patients and they were categorised as good responders, probable responders and non-responders. Those who responded to SK and probable responders were considered to have benefited from thrombolysis.

RESULTS

60 patients (40%) had ASK antibody titres higher than the median. In patients with a window period <6 h, 73% of patients who benefited from thrombolysis had low ASK titres while 100% of the patients who did not benefit had high ASK titres (p=0.001). Similarly, in patients with a window period >6 h, 89% of patients who benefited from thrombolysis had low ASTK titres while 54% of those who did not benefit had high ASK titres (p=0.002).

CONCLUSIONS

ASK antibodies are present in significant titres in a large proportion of patients in developing countries, which leads to failure of thrombolysis in such patients. In endemic areas with high endemic streptococcal infection, alternative agents should be used for thrombolysis in STEMI.

Intrapleural fibrinolytic therapy for pleural infection

Pneumonia with secondary pleural infection causes considerable morbidity and mortality. Intrapleural instillation of fibrinolytic agents to dissolve fibrinous adhesions is intended to improve pleural fluid drainage and prevent pleural loculations. In the last 20 years their application in the every day clinical practice has dragged much of attention and several studies have supported their use in the management of parapneumonic pleural effusions (PPE) and pleural empyema (PE). However, recent published data cast doubt on the effectiveness of intrapleural fibrinolytic agents in promoting drainage of infected pleural effusions. Pending future clinical trials, fibrinolytic therapy may be used selectively in patients who fail drainage with appropriately sized, image-guided chest tubes if reasons exist to delay or avoid definitive surgical drainage. The scope of this article is to systematically review evidence for the efficacy of intrapleural fibrinolytic therapy in the treatment of PPE and PE with emphasis on controlled trials and present some of the future perspectives.

[Clinical phase I trial of concurrent chemo-radiotherapy with S-1 for T2NO glottic carcinoma]

We conducted a phase I study to determine a recommended dose (RD) of S-1 for chemo-radiotherapy consisting of S-1+ radiotherapy for T 2 N 0 larynx cancer. The method of administration used to assess the RD was irradiation with 2 Gy/day for 5 days a week until a total dose of 60 Gy, and concomitant administration of S-1 once a day for 2 weeks beginning on the day therapy was started followed by 2 weeks off the drug and 2 weeks on the drug with the dose escalating from S-1 60 mg/body/day (level 1) to 80 mg/body/day (level 2), and then to 100 mg/body/day (level 3). 18 patients were enrolled. 4 patients developed an adverse event of grade 3 radiation dermatitis which became a dose-limiting toxicity (DLT) at level 3. We then concluded that 100 mg/body/day was the maximum tolerated dose (MTD) of S-1 and decided that the RD of S-1 was 80 mg/body/day.

Pharmacotherapy in complicated parapneumonic pleural effusions and thoracic empyema

Parapneumonic pleural effusions (PPE) and pleural empyema (PE) present a frequently diagnostic and therapeutic challenge in clinical practice. Although pleural diseases have received increased attention during the past decade, there are still many unanswered questions concerning the diagnosis and treatment of PPE and PE. A lack of controlled studies concerning the management of PPE and PE was noted in recent guidelines. The use of fibrinolytics intrapleurally appears to enhance intercostals tube drainage, reducing the requirement for subsequent surgical mechanical debridement. Recently, there has been interest in other intrapleural agents including combination drugs consisting of streptokinase and streptodornase-alpha, Dnase. Factors to be considered in evaluating whether or not intrapleural instillation of fibrinolytics is effective include an assessment of clinical responses. This review discusses the use of fibrinolytic agents as a novel therapeutic options for treating the various stages of parapneumonic effusions and empyemas.

Do Recipients of Kidneys From Donors Treated With Streptokinase Develop Anti-streptokinase Antibodies?

Streptokinase is used for preflush for non-heart-beating donors (NHBDs) in our center. The aim of this study was to evaluate whether the use of thrombolytic streptokinase results in the production of anti-streptokinase antibodies in the recipients after renal transplantation. Recipient sera taken prior to and at 1 and 6 months posttransplant were tested for the presence of antibodies to streptokinase using an enzyme-linked immunosorbent assay assay. No differences were detected between a group of 18 recipients who had kidneys from thrombolytic-treated NHBDs and a further group of 18 who received NHBD kidneys without such treatment.

A rapid agglutination assay to detect anti-streptokinase antibodies

BACKGROUND

Streptokinase resistance may cause suboptimal thrombolytic therapy.

AIM

To develop a rapid latex-bead assay to detect streptokinase antibodies.

METHODS

Sera were obtained from 16 patients presenting with acute myocardial infarction (MI) before treatment with streptokinase and 1 and 6 months post treatment, and from 100 controls. Sera were assayed for anti-streptokinase antibodies using a functional streptokinase-neutralising assay.

RESULTS

Streptokinase-neutralising activity was low in controls (54 +/- 5U/ml) and patients prior to treatment (101 +/- 18), increasing to 2,110 +/- 823 and 1,017 +/- 169 at 1 and 6 months (mean +/- SEM). The latex assay had a sensitivity of 94% and a specificity of 93% for detecting individuals with > 350U/ml of streptokinase resistance, which is sufficient to neutralise the drug clinically.

CONCLUSIONS

Estimation of streptokinase resistance using an enzyme immunoassay and a latex bead assay correlated well with serum neutralising activity. This assay can rapidly identify patients who have a high level of streptokinase-neutralising activity.

Effect of intrapleural streptokinase administration on antistreptokinase antibody level in patients with loculated pleural effusions

BACKGROUND

Streptokinase is widely used IV for the treatment of myocardial infarction and intrapleurally for the treatment of loculated pleural effusions. IV administration of streptokinase is known to cause the production of antistreptokinase antibodies.

OBJECTIVE

The aim of this study was to evaluate whether the intrapleural administration of streptokinase results in a similar elevation of the serum antistreptokinase antibody level.

METHODS

During 1 year, venous blood samples were taken from 16 consecutive patients (10 men and 6 women; age range, 22 to 60 years) requiring intrapleural streptokinase administration (250,000 IU once a day, for 2 to 6 days). Blood samples were taken before treatment, on day 5, and day 14. Antistreptokinase antibodies were measured using enzyme-linked immunosorbent assay (ELISA) and were expressed in arbitrary ELISA units. Four patients with myocardial infarction treated with IV streptokinase (1,500,000 IU) were included as control subjects for the method.

RESULTS

Before treatment, the median antistreptokinase antibody level in patients with loculated pleural effusions was 729 ELISA units (range, 196 to 13,529 ELISA units) and increased to 9,240 ELISA units (range, 1,456 to 77,389 ELISA units) by day 14 (p < 0.0001). In the control group, the median pretreatment level was 119 ELISA units, and by day 14 it had increased to 20,495 ELISA units. Four patients who developed an elevated body temperature after intrapleural administration of streptokinase had a significantly higher pretreatment antistreptokinase antibody level compared to other patients.

CONCLUSIONS

The intrapleural administration of streptokinase results in the elevation of the serum antistreptokinase antibody level, which is similar to the case with IV administration. An increased pretreatment antistreptokinase antibody level does not influence the result of intrapleural fibrinolysis but can cause an elevation of body temperature after the administration of streptokinase.

Thrombolytics: prospects for new agents

Thrombolytic therapy revolutionised the management of acute myocardial infarction (AMI). The ability to re-establish coronary artery patency with intravenous thrombolytic drugs has transformed our therapeutic approach, despite patency failures and re-occlusions. However, the established agents are not perfect and a number of novel thrombolytic drugs have consequently been developed and evaluated. This article reviews the currently available agents, discusses available adjunctive therapies and examines the future developments that may affect the application of this therapy.

Streptokinase-induced platelet activation involves antistreptokinase antibodies and cleavage of protease-activated receptor-1

Streptokinase activates platelets, limiting its effectiveness as a thrombolytic agent. The role of antistreptokinase antibodies and proteases in streptokinase-induced platelet activation was investigated. Streptokinase induced localization of human IgG to the platelet surface, platelet aggregation, and thromboxane A2production. These effects were inhibited by a monoclonal antibody to the platelet Fc receptor, IV.3. The platelet response to streptokinase was also blocked by an antibody directed against the cleavage site of the platelet thrombin receptor, protease-activated receptor-1 (PAR-1), but not by hirudin or an active site thrombin inhibitor, Ro46-6240. In plasma depleted of plasminogen, exogenous wild-type plasminogen, but not an inactive mutant protein, S741A plasminogen, supported platelet aggregation, suggesting that the protease cleaving PAR-1 was streptokinase-plasminogen. Streptokinase-plasminogen cleaved a synthetic peptide corresponding to PAR-1, resulting in generation of PAR-1 tethered ligand sequence and selectively reduced binding of a cleavage-sensitive PAR-1 antibody in intact cells. A combination of streptokinase, plasminogen, and antistreptokinase antibodies activated human erythroleukemic cells and was inhibited by pretreatment with IV.3 or pretreating the cells with the PAR-1 agonist SFLLRN, suggesting Fc receptor and PAR-1 interactions are necessary for cell activation in this system also. Streptokinase-induced platelet activation is dependent on both antistreptokinase-Fc receptor interactions and cleavage of PAR-1.

A mutant streptokinase lacking the C-terminal 42 amino acids is less reactive with preexisting antibodies in patient sera

Streptokinase (SK) is an efficacious thrombolytic drug for the treatment of myocardial infarction. Because of its immunogenicity, patients receiving SK therapy develop high anti-SK antibody (Ab) titers, which might provoke severe allergic reactions and neutralize SK activity. In this report we studied the reactivity of a synthetic 42-residue peptide resembling SKC-2 C-terminus with patient sera. SKC-2(373-414) peptide was recognized by 39 and 64% of patients, before and after SKC-2 therapy, respectively. An SKC-2 deletion mutant (mut-C42), lacking the same 42 C-terminal residues, was constructed and expressed in Escherichia coli. Recognition of mut-C42 by preexisting Abs from patient sera was 51 and 68% of reactivity to SKC-2, as assessed by direct binding and competition assays, respectively. For most of the patients, mut-C42-neutralizing activity titer (NAT) significantly decreased with respect to SKC-2-NAT. This study opens the possibility of producing a less immunogenic variant of SK, which could constitute a preferred alternative for thrombolytic therapy.

A mutant streptokinase lacking the C-terminal 42 amino acids is less immunogenic

Streptokinase (SK) is the most widely used compound for the treatment of myocardial infarction and the least expensive thrombolytic agent, but a drawback to its use is the widespread presence of anti-SK antibodies (Abs). Clinical failure of the activation of the fibrinolytic system by SK has been reported due to the presence of a high titer of anti-SK neutralizing Abs. Patients receiving SK therapy develop high anti-SK antibody titers, which might provoke severe allergic reactions. These Abs are sufficient to neutralize a standard dose of SK up to four years after initial SK administration. This is a clinical problem because of the increasing number of patients who have been treated once with SK for acute myocardial infarction (AMI) and are likely to require plasminogen activator treatment in the future. In previous in vitro studies, we have shown that a deletion mutant (mut-C42), lacking the 42 C-terminal residues, was significantly less antigenic when compared with the native molecule (SKC-2). In this study, 14 monkeys were subjected to treatment with SKC-2 and mut-C42 in order to compare their humoral response by determining SK neutralizing activity in monkey's sera. All monkeys developed anti-SKC-2 Ab titers, but in the case where treatment induced Abs directed against the C-terminus of SKC-2, neutralizing activity against the native protein was significantly higher than that developed against mutant SK mut-C42.

Mapping of the antigenic regions of streptokinase in humans after streptokinase therapy

Streptokinase (SK) is efficaciously used as a thrombolytic drug for the treatment of myocardial infarction. Being a bacterial protein, SK is immunogenic in humans. Therefore, resulting from SK therapy, patients become immunized and anti-SK antibody (Ab) titers rise post-treatment. High Ab titers might provoke severe immune reactions during SK therapy and neutralize SK activity, preventing effective thrombolysis. Spot synthesis combined with peptide library techniques is a useful tool for studying protein-peptide interactions on continuous cellulose membranes. Here, we report on the mapping of antigenic regions of SK using a spot-synthesized peptide library and human total sera from patients receiving SK therapy. All tested samples have high anti-SK Ab titers and most of them show significant SK neutralizing capacity. Individual variations in peptide recognition were detected. However, patients treated with SK tend, in general, to show a common regional binding pattern, including residues 1-20, 130-149, 170-189, and 390-399. This is the first study reporting the probing of a cellulose-bound set of peptides with total human sera.

Streptokinase antibodies inhibit reperfusion during thrombolytic therapy with streptokinase in acute myocardial infarction

OBJECTIVES

To evaluate the influence of pretreatment IgG against streptokinase on the outcome of streptokinase treatment in acute myocardial infarction.

SETTING

Coronary care unit.

DESIGN

From 88 patients admitted to the coronary care unit due to chest pain, blood samples were taken for determination of the pre-existing titre of antibodies against streptokinase. The patients were treated and monitored according to standard protocols. Fifty of the patients received thrombolytic therapy with streptokinase due to acute myocardial infarction and were monitored with continuous dynamic vectorcardiography, making possible the continuous analysis of ST- and QRS-vector changes and determination of the event of reperfusion. None of these 50 patients had been given streptokinase therapy previously.

RESULTS

According to the vectorcardiographic criteria 21(42%) patients had signs of early (within 2 h) reperfusion after streptokinase therapy. These patients had lower pre-existing antibody titres than patients without signs of reperfusion (mean values 0.20 and 0.45 arbitrary units, P = 0.01). None of the patients with a titre higher than 0.50 arbitrary units (nine patients) had signs of early reperfusion. Of the 41 patients with a titre lower than 0.50 arbitrary units 52.5% had signs of early reperfusion.

CONCLUSION

The present investigation indicates that pre-existing streptokinase antibodies play an important role in reperfusion failure during thrombolytic therapy with streptokinase in acute myocardial infarction. Therefore, the determination of streptokinase antibodies may differentiate between those patients who may benefit from streptokinase treatment and those who should be treated with some other regime.

Sequences of antigenic epitopes of streptokinase identified via random peptide libraries displayed on phage

Though streptokinase (SK) is widely used to treat humans with thrombotic disease, it is antigenic and anti-SK antibody causes allergic reactions and neutralizes SK's therapeutic effects. To pinpoint the fine structure of two immunodominant, continuous epitopes in SK, we used unconstrained 15 and 6-mer random peptide libraries displayed on phage (theoretical complexity of 3.2 x 10(19) and 0.64 x 10(8) unique sequences). The first epitope, recognized by both human Ab and murine monoclonal (m)Abs, was previously localized to the amino terminus of SK. Repeated panning and selection experiments against a 15-mer peptide phage library, using a representative mAb (A2.5) to this epitope, identified a dominant structural motif (GP[R/L]WL) corresponding to amino acids 3 to 7 of native SK, which was consistent with previous epitope mapping. These findings were further confirmed by: (1) the fact that a synthetic peptide spanning the epitope of A2.5 (AGPEWLL) specifically inhibited the binding of A2.5 to SK and (2) the finding that mAb 9D10, which competes with mAb A2.5 for binding to SK, independently selected, from a different random hexamer library, an epitope sequence spanning residues 4 to 9 that overlaps the A2.5 epitope. Similar studies of the second epitope in SK, which is immunodominant for murine but not human antibodies, identified a consensus sequence KS(K/L)P(F/Y) corresponding to amino acids 59 to 63 of SK; this was confirmed by epitope peptide binding experiments. This epitope is cleaved and destroyed when SK reacts with human but not murine plasminogen. Thus, pinpointing the sequences of antigenic epitopes of SK: (1) provides a potential explanation for species differences in SK's antigenicity, (2) demonstrates the overlapping fine structure of epitopes recognized by competitive mAbs, (3) confirms previous epitope mapping studies and (4) has the potential to identify antigenic sequences that lead to allergic reactions in patients treated with SK.

Structural characterization of immunodominant regions of streptokinase recognized by murine monoclonal antibodies

In order to determine the nature of the antigenic and functional determinants of streptokinase (SK), we produced monoclonal antibodies (MAbs) by immunizing A/J mice with native SK protein. By virtue of their differential binding to a large panel of recombinant SK truncated proteins, and their effect on the formation of functional SK-plasminogen activator complex (SKPAC), these MAbs were found to recognize 6 unique and minimally overlapping epitopes on the SK protein. The fine epitope specificity of the anti-SK MAbs derived from A/J mice was compared with that of MAbs derived from BALB/c mice. A number of MAbs from both inbred strains of mice were directed against the same sequences of SK (1-13, 1-253, 120-352) suggesting that these regions of the molecule contain peptide sequences that are immunodominant. Two of the "immunodominant" sequences of SK protein appeared to be important for SK function, since the formation of SKPAC could be inhibited by MAbs against these sequences.

Neutralising antibodies after streptokinase treatment for myocardial infarction: a persisting puzzle

OBJECTIVE

To determine the development of titres of streptokinase (SK) neutralising antibodies after a single dose of SK, to establish when titres decrease to levels at which a second dose might be effective.

DESIGN

Analyses of blood samples taken from patients at intervals after SK administration.

SETTING

Australian public hospital.

PATIENTS

104 patients with acute myocardial infarction who were treated with SK and 27 controls who were not.

OUTCOME MEASURE

SK neutralising antibodies were measured once in each of the 27 controls and on 166 occasions in the 104 treated patients.

RESULTS

Titres of SK neutralising antibodies rose after SK administration but returned to control levels by 2 years.

CONCLUSIONS

SK might be effective again as a thrombolytic agent as early as 2 years after a single dose. These results are at variance with most previously published data and the reasons for this are not clear. Data evaluating patency rates after standard doses of streptokinase in patients with increased titres of neutralising antibodies are necessary before re-exposure to streptokinase can be recommended.

How safe is the readministration of streptokinase?

Streptokinase is an antigenic thrombolytic agent used for the treatment of acute myocardial infarction. It reduces mortality as effectively as the nonantigenic alteplase in most infarct patients while having the advantage of being much less expensive. This cost implication is important since myocardial reinfarction is common, with fibrinolytic therapy indicated in many patients with reinfarction. Following streptokinase, antistreptokinase antibodies and neutralisation titres can rise to significant levels from 4 days after the initial dose. These antibodies can presist for at least 4 years in up to 50% of patients. It is possible that these antibodies may cause allergic reactions or neutralisation of a further dose of streptokinase, rendering it ineffective for the treatment of myocardial reinfarction. To date, 2 small studies of patients without previous streptokinase exposure suggest that higher antibody titres are associated with a lower rate of coronary reperfusion, while a further study suggests that high titres are associated with hypersensitivity reactions. At present the readministration of streptokinase cannot be recommended from 4 days after a first dose. Further larger studies are needed to assess the effect of high neutralisation titres on coronary reperfusion.

Does the potential for development of streptokinase antibodies change the risk-benefit ratio in older patients?

In patients with acute myocardial infarction (MI), quick initiation of thrombolytic therapy is the best strategy for improvement of survival and reduction of morbidity. Streptokinase, a purified product of haemolytic streptococci, is the most commonly administered agent. The compound anistreplase (a complex of streptokinase to plasminogen), is available but currently not often used. The non-antigenic competitor for these two compounds for the indication of MI is alteplase (recombinant tissue plasminogen activator, rt-PA). Due to former use of streptokinase or its derivative anistreplase, patients may develop specific antibodies to the foreign protein, whereas cross-reacting antibodies may be due to streptococcal infections. These antibodies may neutralise streptokinase or its derivative in case of (re)administration and may mediate adverse events, sometimes serious. Since advanced age by itself is certainly not a contraindication to thrombolytic therapy, and because reinfarction occurs frequently, the benefit-risk ratio of re-exposure to streptokinase or its derivative is decreased in the elderly who present with reinfarction. In the framework of tailored thrombolytic therapy, alteplase or urokinase appear to be the drugs of choice in these patients.

Mapping the antigenic regions of streptokinase in humans before and after streptokinase therapy

Streptokinase saves lives in patients suffering a myocardial infarction. However, because nearly all humans tested show antibodies against streptokinase, allergic reactions to streptokinase are common and may be severe. In this report we have analysed antibodies purified from normal blood donors and patients, before and after streptokinase therapy, to identify antigenic regions of the streptokinase molecule. Antibody to streptokinase was seen in all subjects, but there were 20-30-fold differences between individuals in the antibody titer. These individual differences in titer persisted after SK treatment, though the titer for all patients rose an average of 7-fold 1 week after streptokinase therapy. To identify the regions of streptokinase to which the antibody bound, we employed a panel of well-characterized murine monoclonal antibodies and recombinant streptokinase truncated fragments. Antibodies to three discrete regions of streptokinase could be detected in all patients. Antibodies to two other regions, at the amino terminal and carboxyl terminus of the molecule, were found in many but not in all patients. However, antibodies to a sixth region of streptokinase were uncommon and of very low titer. Interestingly, individuals receiving streptokinase tended to show the same pattern of immunoreactivity after treatment as they had prior to streptokinase. We conclude that although individual differences exist in the titers of streptokinase antibody, certain regions of streptokinase appear to be more antigenic or immunodominant.

Criteria for drug usage review of thrombolytics in acute myocardial infarction

Thrombolytic drugs are now the mainstay of the management of acute myocardial infarction (AMI). Although their use is associated with reduced mortality, significant adverse effects can occur, especially if they are used inappropriately. Drug usage review of this group of drugs provides a measure of the appropriateness of their use. The development of criteria against which the use of these drugs can be compared allows the collection of qualitative and quantitative data on their use. Those criteria identified during this process include: evidence for, and accuracy of, diagnosis of AMI; when, where and how to administer the drug; what drug to use, and at what dose. Identification of potential adverse effects, measures of treatment success and the role of adjunctive therapy may also be included as part of a drug usage evaluation process.

Streptokinase antibodies are of clinical importance and they can be measured in half an hour by a simple enzyme-linked immunosorbent assay

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