Immunological relation between serum antibodies against pneumolysin and against streptolysin O

The immunological relation between serum antibodies to pneumolysin and to streptolysin O was studied in patients with pneumococcal pneumonia (n = 40), patients with infections due to beta-haemolytic streptococci (n = 35), healthy human controls (n = 60) and in rabbits immunized with pneumolysin. There was no correlation between anti-pneumolysin and anti-streptolysin O titers (r = -0.279). The distribution of anti-pneumolysin titers in patients with high anti-streptolysin O titers did not differ from healthy controls. However, there was a tendency to increased or rising anti-streptolysin O titers in patients with pneumococcal infection. Antibodies obtained during pneumococcal infection might thus give false-positive reactions in the streptolysin O neutralization test. Serum antibodies to streptolysin O do not cross-react with pneumolysin in an ELISA. The pneumolysin ELISA for detection of pneumococcal disease will therefore not be disturbed by false-positive reactions due to antibodies directed against beta-haemolytic streptococci.

A sandwich ELISA for bovine serum in viral vaccines

A double antibody sandwich ELISA for the detection of bovine serum in viral vaccines was developed and standardized with commercially available reagents. The detection limit by ELISA was 0.5 ng ml-1. ELISA was found to be 50-400 times more sensitive than the currently used assays. It was concluded that ELISA is a specific, sensitive and reproducible method for the determination of residual amounts of bovine serum in viral vaccines.

Use of erythromycin to prevent pertussis in newborns of mothers with pertussis

During the period 1975-1985, 35 women with serology- or culture-confirmed pertussis at the time of labor were admitted to the Danderyd Hospital (Danderyd, Sweden). In 32 cases, the mothers were allowed to nurse their newborns while receiving erythromycin therapy. Erythromycin prophylaxis was given to 28 newborns. None of the newborns developed clinical or laboratory signs of whooping cough. The therapy was well tolerated by the newborns and did not affect the microflora in the gut. Maternal antibodies to pertussis toxin and to the filamentous hemagglutinin were found in cord blood, and levels decreased during the follow-up period. The study demonstrated that mothers with pertussis can safely be allowed to nurse their infants if both receive erythromycin.

Diagnosis of pneumococcal pneumonia by enzyme-linked immunosorbent assay of antibodies to pneumococcal hemolysin (pneumolysin)

An enzyme-linked immunosorbent assay (ELISA) with a highly purified pneumolysin as the antigen was evaluated for serological diagnosis of pneumococcal pneumonia. One hundred four healthy controls were tested, and the specificity of the test was set to 95%. In samples from patients with bacteremic pneumococcal pneumonia, 82% (18 of 22) were positive, i.e., at least one serum sample had a titer above the upper normal limit or at least a twofold rise in antibody titers was noted. In nonbacteremic pneumococcal pneumonia, 45% (21 of 47) of samples were positive. All sera were negative for patients with pneumonia caused by Haemophilus influenzae, Legionella pneumophila, Chlamydia psittaci, and influenza A virus. However, in patients with a diagnosis of Mycoplasma pneumoniae infection, 8 of 25 (32%) samples were positive for antibodies to pneumolysin. All sera, including those from patients with mycoplasma infection, were negative to a protein control antigen by ELISA. Serum immunoglobulin G response to pneumolysin as measured by ELISA might thus be an aid in the laboratory diagnosis of pneumococcal pneumonia. This assay may also help to further elucidate the occurrence of dual infections with pneumococci.

Serological diagnosis of Borrelia meningitis

The antibody response against a Borrelia strain isolated from Swedish Ixodes ricinus ticks was determined by enzyme linked immunosorbent assay (ELISA) and indirect immunofluorescence assay (IFA) of cerebrospinal fluid (CSF) and serum specimens from 45 patients with chronic meningitis. Probable Borrelia etiology could be demonstrated in 41 of 45 (91%) patients with clinical symptoms of chronic meningitis. Approximately 25% of the patients had significantly elevated titer of antibody to the spirochete in CSF but not in serum. Patients with short duration of disease were especially prone to be antibody negative in serum but positive in CSF. Significant rise in serum antibody titers was seldom demonstrated in patients treated with antibiotics.

Acellular pertussis vaccine in adults: adverse reactions and immune response

An acellular pertussis vaccine JNIH-6 containing pertussis toxin and filamentous hemagglutinin was evaluated in adult volunteers with regard to adverse reactions and antibody response. Adverse reactions were few and mild. A late onset local reaction was seen in 22 of the 47 vaccinees (47%) as compared to none of the 20 subjects receiving a placebo, the carrier solution of aluminium phosphate of the vaccine. The reaction, which manifested itself on the 6th to 8th day after vaccination, consisted in all cases of an induration and/or swelling considered insignificant by the majority of the subjects. The reaction was only found in vaccinees receiving a first dose of vaccine and was independent of the prevaccination antitoxin level. The vaccine induced a highly satisfactory antibody response to both filamentous hemagglutinin and pertussis toxin.

Borrelia arthritis in Sweden

Antibodies to Borrelia spirochetes were determined by an enzyme-linked immunosorbent assay (ELISA) in sera from 298 patients with postinfectious arthritis. Sera from healthy individuals, patients with acute infectious meningitis of proven etiology and patients with multiple sclerosis served as controls. Titers above the 100% percentile of controls were found in five of 298 (2%) arthritis patients. Two of the arthritis patients had higher titers than any titers previously found in Swedish patients with Borrelia meningitis. It is concluded that a Borrelia etiology should be considered in patients with reactive or postinfectious arthritis of unknown origin.

Antitoxin in human pertussis immune globulins

The level of antitoxin i.e. neutralizing antibodies to pertussis toxin, or lymphocytosis promoting factor, was determined in six pertussis immune globulin preparations from different manufactures. A comparison with antitoxin levels after natural pertussis disease in adults showed that pertussis immune globulins did not contain more antitoxin than convalescent phase sera, i.e. they had very low antitoxin content for specific immune globulins. Agglutinin and anti-FHA titres were relatively higher in immune globulins, probably reflecting a difference between the antibody response elicited by whole cell vaccines used for hyperimmunization in immune globulin production and by natural disease. The low antitoxin content of currently available pertussis immune globulin preparations could explain the inefficacy or conflicting results obtained with these products in prophylaxis and therapy of whooping cough.

Experimental mandibular Staphylococcus aureus osteomyelitis; antibody response and treatment with dicloxacillin

Staphylococcus aureus mandibular osteomyelitis was produced in 20 rabbits by injection of a sclerosing agent and 1 X 10(9) colony-forming units of Staphylococcus aureus V8 into the medullary cavity of the mandible. After 2 weeks all rabbits developed infections. 10 of the rabbits were then treated with dicloxacillin (22.5 mg/kg body weight) every 12 h for 7 days and 10 were left untreated. The animals were sacrificed after 8 weeks and histopathological examination was performed. An enzyme-linked immunosorbent assay (ELISA) was used to measure IgG response against staphylococcal teichoic acid and alpha-toxin during the observation period. In the treated group, there was a decrease in clinical symptoms after the treatment period, while in the untreated group, progression of the infection was a common finding. At the end of the treatment period, Staphylococcus aureus V8 could not be recovered from aspirates obtained from animals in the treatment group, while in the non-treatment group, Staphylococcus aureus V8 could be recovered from abscesses in 6 rabbits. Both in the treated group and in the untreated group, the rabbits showed increasing IgG titers against teichoic acid and alpha-toxin during the first 2-3 weeks. No significant differences in antibody response patterns were noted between the treated and untreated groups and no clear correlation between the immunological response and the severity of the disease was observed.

The development and standardization of an ELISA for ovalbumin determination in influenza vaccines

A double antibody sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of ovalbumin in influenza vaccines has been developed and standardized. Commercially available reagents were used. ELISA was compared to single radial immunodiffusion (SRD) and immunoelectro-osmophoresis (IEOP) techniques. The detection limit by ELISA was 0.5 ng/ml. This method was found to be at least 1000 times more sensitive than SRD and at least 200 times more sensitive than IEOP. It was concluded that ELISA is a specific, sensitive and reproducible method for the determination of the small amounts of ovalbumin found as an impurity in unconcentrated influenza vaccines.

The development and standardization of an antigen detection ELISA for rubella virus grown in rabbit cells

A double antibody sandwich ELISA for the detection of rubella virus antigen was developed and standardized. Commercially available antisera were chosen in order to make the assay readily available. Antigen detection gave an excellent correlation to titers obtained by examination of cytopathogenic effect (CPE, r = 0.986). Replication of rubella virus grown in rabbit cells was identified with CPE and positive ELISA appearing within a difference of +/- one day. ELISA provided an objective detection of rubella virus which is often difficult by the reading of CPE. The method was found to be both sensitive and reproducible and facilitated work in rubella virus control involving a large number of virus titrations.

Antibodies to staphylococcal teichoic acid and alpha toxin in patients with cystic fibrosis

Enzyme-linked immunosorbent assay (ELISA) was used for IgG antibody determination to teichoic acid and alpha-toxin from Staphylococcus aureus in 65 patients with cystic fibrosis (CF). In patients chronically colonized with S. aureus, elevated titres to teichoic acid were found in 13/35 (37%) patients, to alpha-toxin in 12/35 (34%) and to either antigen in 18/35 (51%). Patients with elevated titres to teichoic acid had a significantly lower X-ray score than patients with normal titres. The highest titres against both teichoic acid and alpha-toxin were seen in patients not receiving optimal treatment. These findings suggest that staphylococci contribute to the tissue damage in CF and that the determination of antibodies especially to staphylococcal teichoic acid might be of value in the diagnosis and management of staphylococcal infections in patients with CF.

Erythema chronicum migrans in Sweden: clinical manifestations and antibodies to Ixodes ricinus spirochete measured by indirect immunofluorescence and enzyme-linked immunosorbent assay

26 Swedish patients with erythema chronicum migrans (ECM) were studied regarding associated clinical symptoms and antibodies to Swedish Ixodes ricinus spirochete. 11/26 (42%) of the patients had associated symptoms, compared to more than 90% of 314 American patients with ECM, as described by Steere et al. Only 2/26 (8%) had multiple skin lesions, compared to 48% of the American patients. Elevated erythrocyte sedimentation rate and circulating immune complexes were demonstrated in 6/25 (24%) and 8/25 patients (32%), respectively, as against in 53% and 84%, respectively, of the American patients. The antibody response to Ixodes ricinus spirochete was measured by indirect immunofluorescence (IFA) and enzyme-linked immunosorbent assay (ELISA). Compared to the 95% percentile of controls, significantly high antibody titers were demonstrated in 3/25 (12%) by IFA, and 7/25 (28%) by ELISA. The ELISA antibody titers differed significantly (p less than 0.05) between ECM-patients and controls. The spirochetal antibody response in ECM was also compared with that in spirochete-associated disease of the central nervous system.

Diagnosis of spirochetal meningitis by enzyme-linked immunosorbent assay and indirect immunofluorescence assay in serum and cerebrospinal fluid

The antibody response against a spirochetal strain isolated from Swedish Ixodes ricinus ticks was determined by enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence assay of cerebrospinal fluid (CSF) and serum specimens from 45 patients with chronic meningitis. Samples of CSF, serum, or both from patients with various infections of the central nervous system, multiple sclerosis, syphilis, or infectious mononucleosis and from healthy individuals served as control samples. Probable spirochetal etiology could be demonstrated for 41 of 45 (91%) patients with clinical symptoms of chronic meningitis. Approximately 25% of the patients had significantly elevated titers of antibody to the spirochete in CSF but not in serum. The highest diagnostic sensitivity, 91%, was demonstrated by measurement of CSF antibodies and calculation of a spirochetal CSF titer index, which is the ratio of (ELISA titer in CSF/ELISA titer in serum) to (albumin in CSF/albumin in serum) and which also considers the degree of blood-CSF barrier damage. The highest specificity, 98%, was obtained by calculation of a CSF titer index. Patients with short duration of disease were especially prone to be antibody negative in serum but positive in CSF. Significant rise in serum antibody titers was seldom demonstrated in patients treated with antibiotics. It is concluded that measurement of CSF antibodies, especially by ELISA, is a highly sensitive and specific method for the immunological diagnosis of spirochetal meningitis.

Serum antibody response to Clostridium difficile toxins in patients with Clostridium difficile diarrhoea

Consecutive serum samples from 61 patients with Clostridium difficile diarrhoea were investigated for antibody response to C. difficile toxins A and B in an indirect enzyme immunoassay (ELISA) and in a neutralization assay against C. difficile cytotoxin. Sera from 64 blood donors, elderly healthy females and patients with other known intestinal enteropathogens served as controls. An immune response was detected by ELISA in approximately half of the patients with C. difficile diarrhoea. The specificity of the ELISA was 94% or 97%, depending on the control material used. Furthermore, a correlation was found between clinical recovery without relapse of C. difficile diarrhoea and high IgG titers to toxin B in the ELISA, and/or appearance of neutralizing antibodies. It is concluded that the ELISA for detection of serum antibodies to C. difficile toxins may be of diagnostic value in combination with the conventional tissue culture assay for cytotoxin in stool. High ELISA IgG titres to toxin B and/or the appearance of neutralizing antibodies may also be a positive prognostic sign in patients with C. difficile diarrhoea.

Neutralizing antibodies to pertussis toxin in whooping cough

The development and duration of neutralizing antibodies (antitoxin) to pertussis toxin were studied in 38 patients with culture-verified infections due to Bordetella pertussis and one patient with infection due to Bordetella parapertussis. An in vitro neutralization test in microplate culture of Chinese hamster ovary cells was used. An antitoxin response was recorded in 36 patients, the exceptions being two patients treated early with erythromycin (one of whom developed clinical pertussis two years later) and the patient with infection due to B. parapertussis. A long-term follow-up for several months to several years after disease showed maintenance of high antitoxin levels. These results are in accordance with the hypothesis that antibodies to pertussis toxin mediate long-term immunity to whooping cough.

Enzyme immunoassay for detection of Clostridium difficile toxins A and B in patients with antibiotic-associated diarrhoea and colitis

A sandwich enzyme immunoassay (ELISA) was developed to detect Clostridium difficile toxins A and B in stools from patients with antibiotic associated diarrhoea and colitis. Immune serum to crude Clostridium difficile toxin and non-immune serum were coated onto polystyrene microtiter plates to act as capture antibodies; toxins A and B in human stools were detected by antibodies from rabbits immunized with purified toxins A and B. The ELISA for toxin B showed cross-reactions with Clostridium bifermentans and Clostridium sordellii and lacked diagnostic sensitivity in clinical samples. The ELISA for toxin A showed no cross-reactions with other clostridiae investigated and was positive in 33% (62/189) of patients with antibiotic associated diarrhoea. This compared with 38% (71/189) positive in the tissue culture assay for Clostridium difficile cytotoxin. With a predictive value of 96% in clinical specimens, the ELISA for toxin A constitutes a sensitive and specific tool for diagnosis of Clostridium difficile associated diarrhoea and colitis.

Enzyme-linked immunosorbent assay for detection of antibodies to Pseudomonas aeruginosa exoproteins

Enzyme-linked immunosorbent assays were developed with four purified Pseudomonas aeruginosa extracellular proteins (exotoxin A, elastase, alkaline protease, and phospholipase C) to determine antibody levels in sera from healthy subjects and the serological response in patients colonized or infected with Pseudomonas aeruginosa. Five of 39 burn patients with wounds colonized by Pseudomonas aeruginosa had elevated antibody titers to alkaline protease. Response to the other antigens was found in only a few patients. Pseudomonas aeruginosa infections (septicemia, osteitis, pneumonia etc.) resulted in increased antibody levels to exotoxin A or phospholipase C in 15 of 22 patients. These findings suggest that repeated determinations of antibodies to Pseudomonas aeruginosa exotoxin A and phospholipase C might be used to monitor therapy in certain patients with osteitis and other deep Pseudomonas infections.

The standardization of an assay for pertussis toxin and antitoxin in microplate culture of Chinese hamster ovary cells

A microplate assay, based on the clustering effect induced by pertussis toxin (PT) in Chinese hamster ovary (CHO) cells, has been developed and standardized. Toxin titration is done directly in the culture microplate by twofold dilutions of 25 microliters of test material to which are added 10 000 freshly trypsinized cells in 200 microliters of culture medium per well. The dilution causing the clustering effect is determined by direct microscopic observation after 48 h of incubation. The method allows detection of 50-100 pg toxin per millilitre. For determination of neutralizing antibodies (antitoxin), twofold dilutions of 25 microliters of antiserum are first made directly in the culture microplate. Thereafter 25 microliters of toxin, containing four times the minimal clustering concentration, is added to each well. After three hours for neutralization at +37 degrees C, cells are added, incubated and examined as above. The assay has been found to be simple and reproducible for measuring the antibody response to PT in human and different animal sera. For titration of bacteria associated toxin, the CHO cells are seeded and incubated for 24 h before the addition of bacteria. Incubation and examination are done as described for toxin titration.

Ontogeny of IgG2 antibodies against S. aureus teichoic acid in normal and immunodeficient children

Anti-teichoic acid antibodies of various subclasses were found to be effectively transported across the placenta during pregnancy. In adults these antibodies are mainly of the IgG2 subclass although substantial amounts of specific IgG1 antibodies may also be found. During ontogeny, specific IgG1 antibodies develop during the second year of life whereas specific IgG2 antibodies appear markedly later. In IgG2 deficient children, prolonged deficiency of specific anti-teichoic acid antibodies was observed, suggesting a lack of maturation of the appropriate idiotype(s). In children who received a bone marrow transplant from adult donors, engraftment of IgG2 producing cells could be seen, thus transferring the ability to produce specific antibodies.

Ixodes ricinus spirochete infection as the cause of postinfectious arthritis in Sweden

Antibodies to Swedish Ixodes ricinus spirochete were determined by an enzyme-linked immunosorbent assay (ELISA) in sera from 298 patients with postinfectious arthritis. Sera from healthy individuals, patients with acute infectious meningitis of proven etiology and patients with multiple sclerosis served as controls. With the upper limit of normal values set at the 95 percentile of controls, 18 of 298 (6%) arthritis patients had positive serum antibody titres. Titres above the 100 percentile of controls were found in 5 of 298 (2%) arthritis patients. Two of the arthritis patients had extremely high titres--higher than any earlier found in Swedish patients with spirochetal meningitis. The clinical manifestations and laboratory findings in the 5 patients with high spirochetal antibody titres are described. It is concluded that a spirochetal etiology should be considered in patients with reactive or postinfectious arthritis of unknown origin.

Relation between antibody response to Pseudomonas aeruginosa exoproteins and colonization/infection in patients with cystic fibrosis

Enzyme-linked immunosorbent assay (ELISA) was used to measure the antibody response to Pseudomonas aeruginosa exotoxin A, elastase, alkaline protease and phospholipase C in patients with cystic fibrosis (CF). Only the chronically colonized patients showed elevated antibody titres to phospholipase C (22/22 patients), alkaline protease (16/22 patients), exotoxin A (15/22 patients) and elastase (5/22 patients). In a few patients where serial specimens were available, rising titres were recorded to all four antigens during periods of active infection. Antibiotic treatment resulted in decrease of titres against all four antigens, but only the anti-exotoxin A and anti-elastase titres decreased to normal levels. Titres to phospholipase C were the least influenced by antibiotic treatment. The results imply different roles for these exoproteins in chronic colonization versus active infection. The levels of P. aeruginosa antibodies to exoproteins could probably be used in monitoring treatment of patients with CF.