Serodiagnosis of extrapulmonary tuberculosis by enzyme-linked immunosorbent assay (ELISA)

Antibodies against Mycobacterium tuberculosis antigenic glycolipids were determined by enzyme-linked immunosorbent assay (ELISA). The 720 sera were collected from adult patients under investigation, suspected with extrapulmonary tuberculosis. The test performance was estimated according to definitive diagnosis in terms of specificity, sensitivity, positive predictive value and negative predictive value. These parameters calculated on 142 sera from patients with extrapulmonary tuberculosis and on 578 sera from patients with different nontuberculosis diseases were 92%, 81.6%, 70.9% and 95.1%, respectively. The specificity decreased to 85% when tuberculosis was associated with cancer or hepatic cirrhosis. In reactivated tuberculosis the sensitivity and the positive predictive value were 86.9% and 83.3%, respectively. Our results showed that ELISA was conclusive for patients with active tuberculosis, before the initiation of the treatment. The sensitivity decreased to 30% in inactive forms. It was demonstrated that ELISA was positive in cases with negative microscopy genitourinary tuberculosis. ELISA could be used as a supporting test in the laboratory diagnosis of active extrapulmonary tuberculosis in adults, disregarding the site involved.     

Serodiagnosis of Streptococcus pneumoniae infection in guinea pigs by an enzyme-linked immunosorbent assay

Guineapig antibodies to Streptococcus pneumoniae (SPN) serotype 19F were detected by an enzyme-linked immunosorbent assay using a simple procedure. In experimentally infected hosts, antibody was detectable as early as 2 to 3 weeks after infection, and high titres were maintained for a long period. Antibodies higher than 1:64 were regarded as specific. In a field study, high antibody titres were shown in SPN enzootic colonies in contrast to negative or low antibody titres in a majority of the animals from non-enzootic and SPF colonies.     

Enumeration of rhizobia by enzyme-linked immunosorbent assay (ELISA)

The use of the enzyme-linked immunosorbent assay (ELISA) to enumerate rhizobia in peat carrier and in soil has been investigated. The ELISA technique takes less time than the conventional plant infection technique often used to enumerate rhizobia present in the presence of other micro-organisms. A minimum of 10₂–10₃ cells are required for a detectable ELISA reaction, limiting the use of this technique when the number of rhizobia is low.     

Detection of Renibacterium salmoninarum by the enzyme-linked immunosorbent assay (ELISA)

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection and identification of Renibacterium salmoninarum. The immune γ-globulin used in the assay was absorbed with two species of cross-reacting bacteria to make a specific test system. R. salmoninarum could be detected in clinically-diseased fish within 30 minutes of preparing a kidney sample, and thus because of its ease of use, the ELISA could be employed as a rapid field test for bacterial kidney disease (BKD), although isolation of R. salmoninarum was more sensitive than the ELISA for detecting individual carrier fish.     

An enzyme-linked immunosorbent assay (ELISA) for plasma testosterone

A rapid, single extraction ELISA for testosterone in plasma is described, using a standard 96 well microtitre plate. Testosterone is covalently bonded to bovine thyroglobulin and passively adsorbed in guanidine hydrochloride to the ELISA plate, giving an immobilised antigen approach which simplifies subsequent assay standardisation for steroid hormone assays. The addition of standard, sample and first antibody (rabbit anti-testosterone), which is unique for each different assay, is followed by a general procedure which includes washing, addition of peroxidase labelled goat antirabbit IgG, further washing and finally, addition of o-phenylenediamine substrate with colour development and reading of the plate at 492 nm on an automatic ELISA processor. The ELISA assay is compared to a testosterone RIA with 125I-label and has similar specificity and precision to the latter with a quicker processing time, and is more cost effective. The added advantages that ELISA assays confer over RIAs in terms of isotope purchase and disposal make this an ideal procedure for use in a routine steroid laboratory.     

Optimality assessment in the enzyme-linked immunosorbent assay (ELISA)

An optimality criterion is proposed for evaluating the precision of alternative designs in the enzyme-linked immunosorbent assay. Assay profiles are represented as four-parameter logistic functions with parameter estimation based on either a weighted nonlinear regression or a simple nonlinear regression after a logarithmic transformation. Assay design changes are characterized in terms of their effects on parameters in the four-parameter logistic model. General optimality results are derived for the variance of relative potency estimates in routine assay applications.     

An enzyme-linked immunosorbent assay (ELISA) for plasma cortisol

A direct ELISA for plasma cortisol is described which is carried out in a standard 96 well microtitre plate. In this ELISA cortisol-thyroglobulin conjugate is immobilised to the microtitre plate and competes with cortisol in the standard or plasma sample for antibody binding sites. Following washing the rabbit cortisol antibody bound to immobilised cortisol is incubated with peroxidase labelled goat antirabbit IgG. Following further washing o-phenylenediamine is added, colour developed, and the plate read at 492 nm on a standard ELISA plate reader. This ELISA shows good agreement with RIA and its sensitivity, specificity and precision allow its use in the routine steroid laboratory.     

Detection of Bacillus cereus flagellar antigen by enzyme-linked immunosorbent assay (ELISA)

A serological typing scheme of Bacillus cereus has been developed by immunochemical analyses of flagellar antigen using an agglutination method. Enzyme-linked immunosorbent assay (ELISA) for the classification of flagellar serotype of Bacillus cereus had greater sensitivity. 10-500 times, than that of agglutination method. The specificity of flagellar antigen and antibody was determined by immunogold electron microscopy and ELISA inhibition assay. Application of ELISA is useful for the detection of the small amounts and many kinds of antigen-antibody reactions.     

Anti-galactocerebroside antibodiesin human cerebrospinal fluids determined by enzyme-linked immunosorbent assay (ELISA)

The standard ELISA technique was improved for the detection of antigalactocerebroside antibody in biological fluid. Mouse monoclonal antigalactocerebroside antibody was used to demonstrate specificity and sensitivity of the technique. After optimization of the assay, the usefulness of this measurement for the evaluation of patients with multiple sclerosis was assessed. The presence of antigalactocerebroside antibodies in the cerebrospinal fluid of 20 patients with multiple sclerosis, 10 with other neurological diseases and 10 normal individuals was determined. All the CSF samples from normal individuals were negative. In patients with multiple sclerosis 14 of the 20 samples had elevated levels of antigalactocerebroside antibody, whereas with other neurological diseases 5 out of 10 were positive. Antigalactocerebroside levels were lower in samples from patients during an acute relapse than in those from more chronic cases. These results indicate that the presence of anti-galactocerebroside antibody in cerebrospinal fluid is not specific to MS but may reflect previous damage to myelin.Abbreviations and trivial names used ELISA Enzyme-Linked Immunosorbent Assay - CSF cerebrospinal fluid; galacto- or glucocerebroside, ceramide-1-0-beta-galactoside or-glucoside     

An enzyme-linked immunosorbent assay (ELISA) for human corticosteroid-binding globulin

A specific and sensitive enzyme-linked immunosorbent assay (ELISA) of the "sandwich-type" for human corticosteroid-binding globulin was developed. A polyclonal rabbit anti-CBG antibody is immobilised to a microtitre plate. Following incubation of standards and samples a second monospecific rabbit anti-CBG antibody, labelled with alkaline phosphatase, is added. After colour development the microtitre plate is read at 405 nm wavelength. The assay shows good agreement to CBG binding capacity assay and commercially available RIA.     

An enzyme-linked immunosorbent assay (ELISA) for measurement of heterophile antibody

An enzyme-linked immunosorbent assay (ELISA) test has been developed for measurement of heterophile antibody. The microtiter test utilizes a bovine erythrocyte monolayer as antigen and anti-human IgM antiserum conjugated with horseradish peroxidase to measure the degree of binding of the heterophile antibody in the test serum with the erythrocytes. A single serum dilution yields quantitative results when read in a spectrophotometer. The ELISA test showed a sensitivity comparable with the immune adherence hemagglutination assay (IAHA) and other heterophile tests, good reproducibility, and high specificity.     

An enzyme-linked immunosorbent assay (ELISA) of denatured cartilage link protein

Antiserum (MB007) was raised in rabbits to SDS-denatured cartilage link protein in order to develop an enzyme-linked immunosorbent assay (ELISA) to quantify link protein in cartilage extracts. The antibodies were characterized by using native and denatured link protein, either as the immobilised or the inhibiting antigen in the assay, and shown to bind more effectively to denatured link protein. At low concentrations, neither hyaluronate (0-30 micrograms/ml), proteoglycan (0-50 micrograms/ml) nor hyaluronate-binding region (0-3 micrograms/ml) competitively inhibited the link protein assay. However, at higher concentrations of proteoglycan (50 micrograms/ml-4 mg/ml) and hyaluronate-binding region (3-40 micrograms/ml) inhibition was observed. A more highly purified proteoglycan and a further purified hyaluronate-binding region preparation showed identical behaviour. The inhibition produced by proteoglycan and hyaluronate-binding region occurred at approximately equivalent molar concentrations (assuming Mr of 10(6) and 7 X 10(4), respectively). These results suggest that a significant proportion of these polyclonal antibodies recognize an epitope common to link protein and hyaluronate-binding region. However, the possibility that these effects are due to contamination with covalently bound link protein cannot be excluded. Trypsinated aggregates (0-10 micrograms/ml) produced no inhibition in the link protein ELISA, but as higher concentrations the inhibition was approximately 2000-fold lower than might have been expected from the link protein concentration present. Thus, the accessibility and/or binding of the antibodies to link protein was substantially decreased, illustrating masking of the link protein antigenic sites, as found by A. Ratcliffe and T.E. Hardingham (Biochem. J. 213 (1983) 371-378). These studies indicate that link protein in tissue extracts may be quantified in the concentration range 30-200 ng/ml and in the presence of hyaluronate, proteoglycan and hyaluronate-binding region, provided that both the immobilised and extracted link proteins are denatured.     

An enzyme-linked immunosorbent assay (ELISA) for human sex hormone-binding globulin

An enzyme-linked immunosorbent assay (ELISA) of the "sandwich-type" for sex hormone binding globulin (SHBG) has been developed. A rabbit anti-SHBG antibody (RAb) is immobilized to the microtitre plate. After incubation with standards and samples a second monospecific rabbit anti-SHBG antibody, labelled with alkaline phosphatase is added (RAb). Following further washing substrate is added, colour developed and the plate read at 405 nm wavelength on a standard ELISA plate reader. The assay is not influenced by the presence of steroids at the binding site, and shows good agreement to SHBG binding capacity assay and commercially available IRMA. Its sensitivity, specificity and precision allows its use in the routine laboratory. The SHBG ELISA has been used to measure SHBG concentrations in sera of normal men, women, pregnant women, and women receiving high-dose medroxyprogesterone acetate as a treatment of metastatic breast cancer.     

Quantification of two cytochrome P-450 isoenzymes by an enzyme-linked immunosorbent assay (ELISA)

An enzyme linked immunosorbent assay (ELISA) using monoclonal and polyclonal antibodies has been developed to quantify individual cytochrome P-450 isoenzymes in microsomal preparations, namely UT-A and PB-B. This very sensitive method can be used for the rapid processing of large quantities of determinations and requires only limited amounts of antibodies.