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C G Magnusson

Publications and source records attributed to C G Magnusson.

58 records · Page 4Linked to original sources
PubMed1981

Automated particle-counting immunoassay for alpha-fetoprotein.

PACIA, a homogeneous non-radioimmunoassay, has been adapted to the determination of serum alpha 1-fetoprotein. This technique is based on the agglutination of latex particles coated with antibodies to the antigen to be determined. The agglutination is measured by using an optical cell counter designed to count blood cells, to determine the reduction in the number of non-agglutinated particles. Interferences by serum constituents are avoided by coating the particles with the F(ab')2-fragments of th immunoglobulin G fraction of the antiserum. The system is automated, with a sampling rate of 50/h and an incubation time of 26 min. Concentrations used in preparing the standard curve ranged from 1 to 50 microgram/L; analytical recoveries were 93.5 to 98.4%; the correlation coefficient of PACIA with radioimmunoassay, calculated from results on 127 samples, was 0.98; maximum within- and between-assay CVs were 7.4% and 9.6%, respectively.

Agglutination Tests↗
PubMed1981

Automated particle-counting immunoassay for digoxin.

We describe a non-radioisotopic automated immunoassay for serum digoxin in the therapeutic range at 50 samples per hour by use of the particle-counting immunoassay technique and a special reagent, rheumatoid factor. Digoxin is determined by evaluating its inhibitory activity on the agglutination of digoxin-coated latex particles. The agglutinating system consists of the anti-digoxin IgG mixed with rheumatoid factor. This anti-IgG autoantibody reacts with IgG when they are aggregated or bound to a surface. Interference by serum proteins was prevented by pepsin digestion at 37 degrees C. Correlation with radioimmunoassay was r = 0.94 for 109 samples with concentrations between 0 and 5.7 micrograms/L. Analytical recovery overall averaged 102%. Within-assay precision (CV) ranged from 12.5% at 0.96 micrograms/L to 4.4% at 2.97 micrograms/L; between-assay precision varied from 8.4% at 0.75 micrograms/L to 5.8% at 2.92 micrograms/L.

Antigen-Antibody Complex↗
PubMedDate not supplied

Characterisation of recombinant human IgE-Fc fragments expressed in baculovirus-infected insect cells.

IgE mediates its effector functions through the Fc region and it has been demonstrated that structures in the Cvarepsilon3-domain are crucial for FcvarepsilonR-binding. In order to further study structures of importance for the function of IgE, such as the carbohydrates, fragments with unmodified amino acid sequence were blunt-end cloned and expressed in baculovirus-infected Sf9 cells. Two fragments of human IgE, one encompassing the entire Fc-region (rCvarepsilon2-4) and a smaller one comprising the second and third domain (rCvarepsilon2-3), were produced and characterised with respect to epitope expression, glycosylation and FcvarepsilonR-binding. N-terminal analysis showed the expected VCSRDF-sequence of the Cvarepsilon2-domain, confirming correct cleavage of the secretion signal. Immunoblotting and gel permeation chromatography demonstrated that rCvarepsilon2-4 mainly formed a dimer, whereas rCvarepsilon2-3 also existed as monomers and oligomers. Endoglycosidase-treatment revealed that both fragments were N-glycosylated. In inhibition ELISA, rCvarepsilon2-4 and myeloma protein IgE(DES) reacted in a near equimolar way with monoclonal antibodies against the Cvarepsilon2-, Cvarepsilon3- and Cvarepsilon4-domains, whereas rCvarepsilon2-3 only reacted with anti-Cvarepsilon2 mAbs. Moreover, in FACS analysis rCvarepsilon2-4 interacted with two cell-lines constitutively expressing FcvarepsilonRI or FcvarepsilonRII, whereas rCvarepsilon2-3 lacked reactivity. A substantial reduction in the ability of rCvarepsilon2-4, following endoglycosidase treatment, to react with recombinant alpha-chain of the high affinity receptor for IgE in sandwich ELISA, indicated a role of N-linked oligosaccharides in stabilising receptor binding structures. Taken together, our results show that rCvarepsilon2-4, but not rCvarepsilon2-3, will be useful in studies of structure-function relationships of IgE, including the role of N-glycosylation, since it demonstrated appropriate epitope expression, conformation and ability to bind Fcvarepsilon-receptors.

Animals↗