Protection of the Furin Cleavage Site in Low-Toxicity Immunotoxins Based on Pseudomonas Exotoxin A

Recombinant immunotoxins (RITs) are fusions of an Fv-based targeting moiety and a toxin. Pseudomonas exotoxin A (PE) has been used to make several immunotoxins that have been evaluated in clinical trials. Immunogenicity of the bacterial toxin and off-target toxicity have limited the efficacy of these immunotoxins. To address these issues, we have previously made RITs in which the Fv is connected to domain III (PE24) by a furin cleavage site (FCS), thereby removing unneeded sequences of domain II. However, the PE24 containing RITs do not contain the naturally occurring disulfide bond around the furin cleavage sequence, because it was removed when domain II was deleted. This could potentially allow PE24 containing immunotoxins to be cleaved and inactivated before internalization by cell surface furin or other proteases in the blood stream or tumor microenvironment. Here, we describe five new RITs in which a disulfide bond is engineered to protect the FCS. The most active of these, SS1-Fab-DS3-PE24, shows a longer serum half-life than an RIT without the disulfide bond and has the same anti-tumor activity, despite being less cytotoxic in vitro. These results have significance for the production of de-immunized, low toxicity, PE24-based immunotoxins with a longer serum half-life.

The role of serum Pseudomonas aeruginosa antibodies in the diagnosis and follow-up of cystic fibrosis

In cystic fibrosis (CF), if Pseudomonas aeruginosa (Pa) infection is not diagnosed and treated early, chronic colonization occurs, which causes rapid decline in pulmonary functions. The aim of this study was to evaluate Pa antibodies, compare them with Pa cultures and determine their role in early diagnosis and follow-up. Ninety CF patients were included; they were divided into chronic, intermittent, negative, and mucoid groups. They were evaluated every 3-6 months. In each visit, pulmonary function tests and sputum cultures were obtained, and Pa antibodies exotoxin A (ExoA), elastase (ELA) and alkaline protease (AP) were determined in the serum by enzyme-linked immunosorbent assay (ELISA). The most specific test that discriminated chronic colonized patients from noncolonized patients was Pa culture, and the presence of at least one antibody had the highest sensitivity. AP had the highest specificity, and ELA had the highest sensitivity. All antibodies were highest in the mucoid group. ELA was highest in chronic and lowest in the negative group. The presence of antibodies was much higher than positive Pa cultures in patients younger than five years of age. A negative correlation between forced expiratory volume in 1 second (FEV1) and AP was determined only in the mucoid group. In the two-year follow-up, antibody presence did not show a regular pattern. In CF, Pa antibodies can be early markers for diagnosis, especially in young children who cannot expectorate, but they should only be used together with sputum cultures for long-term follow-up and treatment.

A case of naturally acquired inhalation anthrax: clinical care and analyses of anti-protective antigen immunoglobulin G and lethal factor

This report describes the first case of naturally acquired inhalation anthrax in the United States since 1976. The patient's clinical course included adjunctive treatment with human anthrax immunoglobulin. Clinical correlation of serologic assays for the lethal factor component of lethal toxin and anti-protective antigen immunoglobulin G are also presented.

Phase I clinical study of the recombinant antibody toxin scFv(FRP5)-ETA specific for the ErbB2/HER2 receptor in patients with advanced solid malignomas

INTRODUCTION

ScFv(FRP5)-ETA is a recombinant antibody toxin with binding specificity for ErbB2 (HER2). It consists of an N-terminal single-chain antibody fragment (scFv), genetically linked to truncated Pseudomonas exotoxin A (ETA). Potent antitumoral activity of scFv(FRP5)-ETA against ErbB2-overexpressing tumor cells was previously demonstrated in vitro and in animal models. Here we report the first systemic application of scFv(FRP5)-ETA in human cancer patients.

METHODS

We have performed a phase I dose-finding study, with the objective to assess the maximum tolerated dose and the dose-limiting toxicity of intravenously injected scFv(FRP5)-ETA. Eighteen patients suffering from ErbB2-expressing metastatic breast cancers, prostate cancers, head and neck cancer, non small cell lung cancer, or transitional cell carcinoma were treated. Dose levels of 2, 4, 10, 12.5, and 20 microg/kg scFv(FRP5)-ETA were administered as five daily infusions each for two consecutive weeks.

RESULTS

No hematologic, renal, and/or cardiovascular toxicities were noted in any of the patients treated. However, transient elevation of liver enzymes was observed, and considered dose limiting, in one of six patients at the maximum tolerated dose of 12.5 microg/kg, and in two of three patients at 20 microg/kg. Fifteen minutes after injection, peak concentrations of more than 100 ng/ml scFv(FRP5)-ETA were obtained at a dose of 10 microg/kg, indicating that predicted therapeutic levels of the recombinant protein can be applied without inducing toxic side effects. Induction of antibodies against scFv(FRP5)-ETA was observed 8 days after initiation of therapy in 13 patients investigated, but only in five of these patients could neutralizing activity be detected. Two patients showed stable disease and in three patients clinical signs of activity in terms of signs and symptoms were observed (all treated at doses > or = 10 microg/kg). Disease progression occurred in 11 of the patients.

CONCLUSION

Our results demonstrate that systemic therapy with scFv(FRP5)-ETA can be safely administered up to a maximum tolerated dose of 12.5 microg/kg in patients with ErbB2-expressing tumors, justifying further clinical development.

Detection of circulating superantigens in an intensive care unit population

OBJECTIVE

Plasma concentrations of superantigens were measured in an intensive care unit (ICU) population and the relationship of superantigen positive rates with the presence of sepsis was investigated.

METHODS

Plasma samples were collected at least twice a week from 78 patients whose primary diagnoses were abdominal disorders (n = 27), respiratory disorders (n = 11), trauma (n = 10), burns (n = 10), cardiovascular disorders (n = 4), neurological disorders (n = 2), and others (n = 14). Five different species of superantigens, i.e., staphylococcal enterotoxins A, B, and C (SEA, SEB, and SEC), toxic shock syndrome toxin-1 (TSST-1), and streptococcal pyrogenic exotoxin A (SPEA), were measured using an enzyme-linked immunosorbent assay.

RESULTS

Significant levels of plasma superantigens were detected in 16 patients. SEA was found in seven patients, SEB in four patients, SEC in two patients, TSST-1 in six patients, and SPEA in five patients. Superantigen detection rates were 6% (1/17) in patients without systemic inflammatory response syndrome (SIRS), 0% (0/21) in SIRS patients without infection, 31% (5/16) in septic patients without shock, and 42% (10/24) in septic shock patients.

CONCLUSIONS

The presence of superantigens was confirmed in part of the ICU population. The role of superantigens in the pathogenesis of sepsis remains to be determined.

Histopathologic changes in kidney and liver correlate with streptococcal pyrogenic exotoxin B production in the mouse model of group A streptococcal infection

Previous studies show that isogenic mutants deficient in streptococcal pyrogenic exotoxin B (SPE B) cause less mortality and skin tissue damage than wild-type strains of Streptococcus pyogenes when inoculated into mice via an air pouch. In this study, the growth and dissemination of bacteria, pathologic changes in various organs, and their correlation with SPE B production were examined. Bacterial numbers in the air pouch from wild-type strain NZ131-infected mice increased at 48 h, while those from speB mutant SW510-infected mice continuously reduced. Mice infected with NZ131 developed bacteremia and greater dissemination in the kidney, liver, and spleen; those infected with SW510 showed either no or slight bacteremia and dissemination. Co-inoculation of SW510 with recombinant SPE B showed a higher bacterial count in the air pouch, bacteremia, and organ dissemination compared to co-inoculation with a C192S mutant lacking protease activity. The histopathologic changes examined showed lesions in kidney and liver in the NZ131-infected but not in SW510-infected mice. The elevation in sera of BUN, AST, and ALT correlated positively with renal and liver impairment. Taken together, SPE B produced during S. pyogenes infection plays a pathogenic role. A direct effect of SPE B on vessel permeability change was also demonstrated.

In vitro and in vivo cytotoxic activities of recombinant immunotoxin 8H9(Fv)-PE38 against breast cancer, osteosarcoma, and neuroblastoma

The 8H9 monoclonal antibody (MAb) is highly reactive with a cell surface glycoprotein expressed on human breast cancers, childhood sarcomas, and neuroblastomas but is not reactive with the cell surface of normal human tissues. This specific reactivity suggests that MAb 8H9 may be useful for targeted cancer therapy. To explore this possibility, we generated two recombinant immunotoxins (ITs) using the single-chain Fv (scFv) of MAb 8H9. Initially the 8H9(scFv) cDNA was fused to a DNA encoding a 38-kDa truncated form of Pseudomonas exotoxin (PE38) to generate the IT 8H9(scFv)-PE38. The fusion gene was expressed in Escherichia coli, and the IT was purified to near homogeneity from inclusion bodies. The purified IT showed specific cytotoxicity on nine different cancer cell lines derived from breast cancer, osteosarcoma, and neuroblastomas, known to react with MAb 8H9. The cytotoxic activity was inhibited by MAb 8H9, showing the cytotoxic activity is specific. The antitumor activity of 8H9(scFv)-PE38 was evaluated in severe combined immunodeficient mice bearing MCF-7 breast cancers or OHS-M1 osteosarcomas. The IT showed a specific dose-dependent antitumor activity at 0.075 and 0.15 mg/kg. Next, a more stable disulfide-linked IT, 8H9(dsFv)-PE38, was constructed. It was produced in high yield (16%) and showed cytotoxic and antitumor activities similar to those of 8H9(scFv)-PE38. 8H9(dsFv)-PE38 was given to two cynomolgus monkeys at doses of 0.1 and 0.2 mg/kg i.v. QOD x 3 and was well tolerated. This shows that a dose that causes significant tumor regressions in mice is well tolerated by monkeys. These results make 8H9(dsFv)-PE38 a candidate for further development as a therapeutic agent for breast cancers, osteosarcomas, and neuroblastomas.

Safety, tolerability, and tumor response of IL4-Pseudomonas exotoxin (NBI-3001) in patients with recurrent malignant glioma

PURPOSE

This was an open-label, dose-escalation trial of intratumoral administration of IL-4 Pseudomonas exotoxin (NBI-3001) in patients with recurrent malignant glioma.

PATIENTS AND METHODS

A total of 31 patients with histologically verified supratentorial grades 3 and 4 astrocytoma were studied. Of these, 25 patients were diagnosed with glioblastoma multiforme (GBM) while six were diagnosed with anaplastic astrocytoma. Patients were over 18 years of age and had Karnofsky performance scores > or = 60. Patients were assigned to one of four dose groups in a dose-escalation fashion: 6 microg/ml x 40 ml, 9 microg/ml x 40 ml, 15 microg/ml x 40 ml, or 9 microg/ml x 100 ml of NBI-3001 administered via convection-enhanced delivery intratumorally using stereotactically placed catheters. Patients were followed with serial MRI scans and clinical assessments every four weeks for the first 16 weeks and then every eight weeks until week 26.

RESULTS

No drug-related systemic toxicity, as evident by lack of hematological or serum chemical changes, was apparent in any patients; treatment-related adverse effects were limited to the central nervous system. No deaths were attributable to treatment. Drug-related grade 3 or 4 toxicity was seen in 39% of patients in all dose groups and 22% of patients at the maximum tolerated dose of 6 microg/ml x 40 ml. The overall median survival was 8.2 months with a median survival of 5.8 months for the GBM patients. Six-month survival was 52% and 48%, respectively. Gadolinium-enhanced magnetic resonance imaging of the brain showed areas of decreased signal intensity within the tumor consistent with tumor necrosis following treatment in many patients.

CONCLUSIONS

NBI-3001 appears to have an acceptable safety and toxicity profile when administered intratumorally in patients with recurrent malignant glioma.

Sensitive enzyme-linked immunosorbent assays for the detection of bacterial superantigens and antibodies against them in human plasma

Enzyme-linked immunosorbent assays for the quantitation of bacterial superantigens, staphylococcal enterotoxins A, B and C, toxic-shock syndrome toxin-1 and streptococcal pyrogenic exotoxin A, were developed. The assays had sensitivity to quantitate these toxins to 1.4, 5.9, 16.3, 2.5 and 4.3 pg/ml, respectively, in a buffer including 50% human plasma. It takes only 150 min to complete the assays after plate preparation. Specificity of the assays agreed with those of reverse latex agglutination assay. We also developed enzyme-linked immunosorbent assays to detect antibodies against these five superantigens. The assays are expected to be significant tools for the study of superantigens in several diseases.

Cerebellar ataxia following whooping cough

Bordetella pertussis (BP), the agent of whooping cough, has not been recognized so far as a cause of permanent cerebellar ataxia in human. We describe three patients who developed a disabling and permanent cerebellar syndrome soon after whooping cough. In two patients, diagnosis of BP infection was confirmed by culture of nasopharyngeal secretions. The infection occurred between the age of 13 and 15 years, with neurological symptoms beginning after a delay varying from 3 weeks to 3 months. In our three patients, the cerebellar syndrome was characterized by dysmetria of ocular saccades, scanning speech and ataxic gait. Brain MRI demonstrated a pancerebellar atrophy. The pathogenesis of this cerebellar degeneration is not established. Experimental studies have demonstrated that the cerebellum is particularly vulnerable to lymphocytosis-promoting factor (LPF), one of the exotoxins from BP. The mechanism of this toxicity might be a marked increase in the cellular levels of 3',5'cyclic guanosine monophosphate (cGMP). Since whooping cough is a bacterial exotoxin-mediated disease, this is the first report of a cerebellar syndrome triggered by a bacterial exotoxin.

["Streptococcal toxic shock-like syndrome"]

Since the mid-1980s increasing numbers of severe group A streptococcal infections (Streptococcus pyogenes) have been reported worldwide. Younger, healthy patients after minor local trauma are most commonly afflicted. The infection is characterized by a rapid course with shock, sepsis, multiorgan failure, soft-tissue infection and a high mortality rate. This special disease has been termed "streptococcal toxic shock-like syndrome". The M-proteins, especially types 1 and 3, and the streptococcal pyrogenic exotoxin A (speA) might play an important role in the pathogenesis of the infection. High dose therapy with antibiotics, monitoring in the intensive care unit and early, aggressive and often multiple debridement of necrotic soft tissue are necessary to save the patient's life.

Development of an immunoassay for BMS-191352, a single-chain immunotoxin, and its application to toxicokinetic studies

BMS-191352 is a single-chain fusion protein composed of the variable regions of chimeric BR96 monoclonal antibody and the binding defective form of Pseudomonas Exotoxin A (PE40). The immunotoxin exhibits potent cytotoxicity against tumor cells expressing the Lewis antigen. A sensitive and specific double antibody sandwich ELISA has been developed and validated for the determination of BMS-191352 in rat and dog EDTA plasma. A monoclonal anti-PE40 antibody (EXA2-1H8) was used to capture BMS-191352 in plasma samples. The captured BMS-191352 was then detected using a biotinylated monoclonal BR96 antiidiotypic antibody (757-4-1) followed by the addition of streptavidin-horseradish peroxidase conjugate and chromogen 3,3',5,5'-tetramethylbenzidine. The optical density was measured at 450 nm. The standard curve range in rat and dog plasma was 2-32 ng/mL. The RSD for the inter- and intra-assay precision was within 9.2% and the accuracy was greater than 89.0%. The ELISA method was applied to the analysis of BMS-191352 in plasma samples from toxicokinetic studies conducted in rats and dogs. These studies revealed that the systemic exposure of BMS-191352 was dose proportional and the kinetics of BMS-191352 were linear between the dose range of 1.8-7.2 mg/m2 in the dog.

Identification of epitopes on a mutant form of Pseudomonas exotoxin using serum from humans treated with Pseudomonas exotoxin containing immunotoxins

PE38 is a 38-kDa derivative of the 66-kDa Pseudomonas exotoxin (PE) in which the cell binding domain of PE (domain Ia, amino acids 1-252) and a portion of domain Ib (amino acids 365-380) are deleted. The immunotoxins LMB-1 and LMB-7 contain PE38 and kill cancer cells by exploiting the cytotoxic action of PE38. The major human B cell epitopes of PE38 were mapped by measuring the reactivity of 45 serum samples from patients treated with the PE38-containing immunotoxins LMB-1 or LMB-7 to two panels of overlapping synthetic peptides representing the sequence of PE38. One panel of peptides is ten amino acids long and overlap by seven amino acids, and the second panel of peptides is twenty amino acids long and overlap by ten. Five major epitopes were identified: amino acids 274-283, 470-492, 531-540, 555-564, and the C-terminal amino acids 596-609. Two minor epitopes were identified as well: amino acids 501-510 and 582-589. These epitopes are predominantly located on the surface of the protein. The amino acids believed to be critical for binding are highly solvent-accessible residues. The results of the human antibody response to peptides are compared to the pattern of reactivity previously identified with serum samples obtained from monkeys administered LMB-1 and LMB-7. The epitopes between monkey and human are almost identical, demonstrating similarity in the response of antibody repertoires between the two species and providing further support that these are the immunodominant epitopes. This information is critical for genetically engineering less immunogenic immunotoxins and provides a foundation for the development of a vaccine against pseudomonal infections which plague immunocompromised individuals and individuals with cystic fibrosis.

Streptococcal pyrogenic exotoxin A release, distribution, and role in a murine model of fasciitis and multiorgan failure due to Streptococcus pyogenes

The role of streptococcal pyrogenic exotoxin A (SPEA) was evaluated in a murine model of fasciitis and multiorgan failure due to a toxigenic strain of Streptococcus pyogenes. Increased serum levels of SPEA at 15 and 21 h were associated with a survival time of <24 h. Levels of SPEA correlated with interleukin-6 levels. Immunostaining showed SPEA localized to renal and hepatic cells. Neutralizing rabbit antibody to SPEA was administered to mice challenged with S. pyogenes, but no effect on survival was observed. Vaccination of mice with recombinant SPEA enhanced mortality due to streptococcal infection, despite the development of neutralizing immunity to the toxin prior to infection. Hence, SPEA is produced systemically during S. pyogenes soft-tissue infection, and increased levels are associated with reduced survival. In this model, however, SPEA did not appear to play a dominant role in pathogenesis; passive immunization against SPEA was not protective, and active immunization enhanced mortality.

Administration of disulfide-stabilized Fv-immunotoxins B1(dsFv)-PE38 and B3(dsFv)-PE38 by continuous infusion increases their efficacy in curing large tumor xenografts in nude mice

B1 (dsFv)-PE38 and B3(dsFv)-PE38 are recombinant immunotoxins in which the Fv fragments of MAbs B1 and B3, respectively, are stabilized by an engineered interchain disulfide bond and are fused at their C-termini to a modified Pseudomonas exotoxin from which the cell-binding domain has been deleted (PE38). Both immunotoxins have been shown to be specifically cytotoxic toward human cancer cell lines which express Le gamma-related carbohydrates on their surface, and when given i.v., eradicated 30- to 50-mm3 s.c. A431 tumors growing in nude mice. A major advantage of dsFv-immunotoxins is their stability at 37 degrees C compared with the relatively unstable single-chain Fvs. This allows them to be given continuously by osmotic pumps placed in the peritoneal cavity. In an attempt to increase the therapeutic index of the immunotoxins, we have now delivered them continuously for 6 days through mini-osmotic pumps placed in the peritoneal cavity of tumor-bearing nude mice. Using this mode of administration, we were able to maintain a constant level of immunotoxin in the serum which was non-toxic to the mice, but caused complete regressions of large 150- to 200-mm3 tumors which lasted for over a month at 1/11 of the LD50 with B1(dsFv)-PE38 and 1/6 of the LD50 with B3(dsFv)-PE38. Complete regression of tumors of similar size could also be achieved by i.v. bolus injections of these immunotoxins at 1/7 of the LD50 with B1(dsFv)-PE38) and 1/3 of the LD50 with B3(dsFv)-PE38. These results suggest that in patients it may be advantageous to administer dsFv-immunotoxins by continuous infusion, since a larger therapeutic index is achieved.

[Optimization of artificial pulmonary ventilation in patients with organophosphorus compound poisoning complicated by development of exotoxic shock]

Central hemodynamics, phase structure of left-ventricular systole, and paO2 were studied in 104 patients with organophosphorus poisoning complicated by exotoxic shock during forced ventilation of the lungs (FVL) with positive zero expiration pressure, positive end expiration pressure +5, +7, +10 cm H2O, and high-frequency FVL. FVL with positive end expiration pressure +5 or +10 cm H2O was found to be the optimal for patients with compensated shock. In patients with decompensated phase of exotoxic shock FVL with positive zero expiration pressure and FVL with positive end expiration pressure +5 cm H2O, although having no negative impact on the hemo- and cardiodynamics, did not provide sufficient oxygenation of the blood. Higher values of positive end expiration pressure (+7, +10 cm H2O) brought about disorders of heart work. High-frequency FVL appears to be the most rational in patients with decompensated phase of shock.

[The production of erythrogenic toxin and the epidemic process in respiratory streptococcal infection]

The capacity of Streptococcus pyogenes, isolated from clinically healthy children in a large organized group, for producing erythrogenic toxin A, B and C was studied. The dynamics of toxin production was compared with changes in the levels of morbidity and carrier state, as well as with some characteristics of the interaction between the populations of the infective agent and the host by such values as virulence and susceptibility. Similarity in the dynamics of the parameters under study was noted. The seasonal dynamics of characteristics which determined the capacity for toxin production significantly influenced the levels and one year morbidity dynamics with respiratory streptococcal infection. The study demonstrated the information value of the characteristics of toxin production for understanding both the interval mechanisms of the epidemic process and the influence of the external ones on subsequent epidemic situation.

In vivo activities of acidic fibroblast growth factor-Pseudomonas exotoxin fusion proteins

Fibroblast growth factor receptors are highly expressed in a variety of cancer cells and activated vasculature. Using chimeric toxins targeted to cell-surface a FGF receptors, we have demonstrated specific cytotoxic activity to these cell types. These molecules, aFGF-PE40 and aFGF-PE40 KDEL, are fusion proteins containing acidic FGF and either a 40- or a 66-kDa binding defective form of Pseudomonas exotoxin, respectively. Both aFGF-toxin fusion proteins were able to inhibit protein synthesis in vitro in a variety of carcinoma cell lines. The half-life of aFGF-PE40 in serum was found to be 41 min when coadministered with heparin. Administration of aFGF-PE40 or aFGF-PE4E KDEL with heparin inhibits the growth of established KB and preestablished A431 epidermoid carcinoma xenografts in athymic mice. The antitumor activities of the two aFGF-toxin fusion proteins were equivalent against the KB tumor xenografts. While we were able to slow the growth of the KB tumor xenografts, we were unable to cause tumor regressions. Histochemical analysis of treated versus untreated tumor tissue revealed a difference in tumor size but not of vascularity. We conclude that aFGF-PE40 and aFGF-PE4E KDEL have in vivo antitumor activity that targets the tumor cell mass rather than vascular structures in mice xenografted with human epidermoid carcinoma.

Probable role of Streptococcus pyogenes in Kawasaki disease

Over the past 25 years, the clinical course of Kawasaki disease has been defined, the prevalence and nature of the cardiovascular effects widely understood, and pathological changes in the most severe cases well described. However, the aetiology and pathogenesis of this puzzling disease have remained unclear, thus specific therapy is not yet available. Because of some close clinical similarities between this disease and streptococcal scarlet fever, particular attention has been paid to the possible role of Streptococcus pyogenes as an aetiological agent in this illness. Until now, however, group A beta-haemolytic streptococci have never been consistently isolated from any patients; in addition, the titre of anti-streptolysin 0 is not raised, and lack of response to antibiotics is a feature of this disease. Our long series of investigations over more than 10 years, which will be covered in the present review, were performed in an attempt at elucidating causative agent(s) of Kawasaki disease. This has led to our firm belief in the probable role of S. pyogenes in the pathogenesis of this disease, despite the lack of fulfillment of Koch's postulates, on the basis of the following findings. Patients with Kawasaki disease recovering from the acute, febrile phase of the illness exhibited an exaggerated cell-mediated reactivity, as measured by the macrophage migration inhibition test, to group A beta-haemolytic streptococci, their pyrogenic exotoxin and streptolysin 0 as well as to several mammalian muscle cell extracts which are allegedly related antigenically to the cell wall and/or cytoplasmic membrane of S. pyogenes. Protoplast-like "spherical bodies" varying in diameter from 0.5 to 1.5 microns, and devoid of cell walls, were detected in the buffy coats of peripheral blood from patients with this disease, and stained distinctly by immuno-electron microscopy using, as a primary antibody, a rabbit antiserum to S. pyogenes- derived protoplasts, and followed by absorption with protoplasts from Staphylococcus aureus and Escherichia coli. Newborn mice infected with S. pyogenes having no capacity to confer cell-mediated immunity even in adult murine hosts, and reinfected 4-6 weeks later with another strain of the same species of bacteria which is able to elicit cellular immunity, showed a lack of humoral response to streptococcal antigens, leaving intact cell-mediated immunity. Such a biased immunological characteristic is an exact counterpart of that of Kawasaki disease patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration of IL-2-PE40 via osmotic pumps prevents adjuvant induced arthritis in rats. Improved therapeutic index of IL-2-PE40 administered by continuous infusion

IL-2-PE40 is a chimeric cytotoxin composed of interleukin 2 (IL-2) fused to a truncated form of Pseudomonas exotoxin (PE) that lacks its binding domain. IL-2-PE40 has been shown to exhibit therapeutic potency in several models in vivo when administered i.p. twice a day. Here we show that the continuous administration of IL-2-PE40 by an osmotic pump specifically prevents the development of adjuvant induced arthritis in rats with an improved therapeutic efficacy as compared to daily repeated i.p. injections. Stabilization of IL-2-PE40 at 37 degrees C for the continuous administration by pumps was achieved by adding NAD, the substrate for the enzyme portion of the chimeric toxin.

Antitumor activity in mice of an immunotoxin made with anti-transferrin receptor and a recombinant form of Pseudomonas exotoxin

LysPE40 is a modified form of Pseudomonas exotoxin that lacks the cell-binding domain and has a chemically reactive lysine residue near the amino terminus. LysPE40 is made in Escherichia coli and secreted into the medium from which it is readily purified. Two immunotoxins were constructed by coupling LysPE40 to an antibody to the human transferrin receptor (TFR) or to an antibody to the human interleukin-2 receptor. These immunotoxins were selectively cytotoxic to receptor-bearing cells in tissue culture. Anti-TFR-LysPE40 given intraperitoneally to mice appeared rapidly in the blood and caused regression of A431 tumors growing as subcutaneous xenografts. These results show that it is possible to cause regression of a solid carcinoma by an immunotoxin if proper targeting can be achieved.

Possible role of Streptococcus pyogenes in mucocutaneous lymph node syndrome. IX. Quantitation by ELISA of streptococcal pyrogenic exotoxin in the serum of MCLS patients

In the present paper we describe the use of an enzyme-linked immunosorbent assay reinforced with an introduction of monoclonal antibody, for the detection and quantitation of streptococcal pyrogenic exotoxin (SPE) in the serum of patients with mucocutaneous lymph node syndrome (MCLS). The amount of SPE was usually at a high level, and its 100% incidence in patients' sera was proved whenever the assay was made on the day of admission, thereby showing a marked contrast to carefully matched control sera which failed to mediate any positive result. As for the change in detected amount of the toxin, a clear dichotomy was observed between the serum of gammaglobulin-treated patients and that of infants given aspirin; in the former the positive result turned to negative rapidly following the initiation of treatment coupled with a defervescence, while in the latter the reduction of SPE levels was scarcely monitored for as long as 17 days after the onset of illness. Quantitation of SPE might be an auxiliary test for the diagnosis of MCLS, because a considerable amount of SPE was assessed in a patient who developed characteristic huge coronary artery aneurysms following an illness which did not fulfill the diagnostic criteria. These findings support our speculation in relation to the certain role of S. pyogenes as an etiological agent for MCLS. The possible mechanisms of gammaglobulin treatment in reducing the prevalence of cardiovascular lesions and the duration of systemic inflammation are discussed.