Measurement of serum chorionic gonadotropin by a biotin-avidin labeled enzyme immunoassay.

A biotin-avidin enzyme immunoassay (EIA) for the measurement of human chorionic gonadotropin (hCG) in serum is described. This procedure involves the use of specific antibody immobilized on beads, biotin-labeled specific antibody, and enzyme-labeled avidin. Reproducible results were achieved within three hours for hCG in serum in the range of two mIU/ml to 150 mIU/ml. HCG levels as low as 0.4 mIU/ml can be measured. The biotin-avidin EIA and two commercially-available radioimmunoassay (RIA) kits were used to determine serum hCG levels on a group of patient samples. Good agreement was found between the biotin-avidin EIA and the RIA methods.

A solid phase enzyme immunoassay for the quantitation of serum ferritin.

A non-competitive solid phase enzyme immunoassay for the measurement of ferritin in human serum is described. This procedure involves the use of specific antibody covalently attached to derivatized hydrophilic microparticles and enzyme labeled specific antibody. Reproducible results were achieved within 4 h for ferritin in serum in the range of 4 ng/ml to 250 ng/ml. Ferritin levels as low as 0.4 ng/ml can be measured. The enzyme immunoassay and three commercially available radioimmunoassay(RIA) kits were used to determine serum ferritin levels in healthy adults. Good agreement was found between the enzyme immunoassay and the RIA methods.

A solid-phase fluoroimmunoassay for the quantitation of antibodies to Toxoplasma gondii.

A solid-phase fluoroimmunoassay (FIAX¿) for the detection and quantitation of human antibodies to Toxoplasma gondii is described. The method is a modification of the procedure of Walls and Barnhart [1] which differs from the earlier test in that it uses a dual rather than single surface StiQTM Sampler, having both an antigen and a control surface. Each sampler is carried through four steps: reaction with diluted serum, a buffer wash, reaction with FITC-labeled goat anti-human IgG, and a final buffer wash. The fluorescence of each surface is measured using a dedicated surface-reading fluorometer. Serum titers are interpolated from a standard curve. The antibody titers of 233 sera were determined by both the indirect immunofluorescent antibody (IFA) and the FIAX¿ assays. The titers determined by the two tests agreed within one four-fold dilution for 226 (97%) of the sera. For replicates (n = 21) of the sera with low, mid and high antibody titers the coefficients of variation were 13.6, 10.0, and 12.3% respectively.

A solid phase fluorescent immunoassay for the quantitation of the C3 component of human complement.

A non-competitive method for the determination of the C3 component of human complement in serum is described. This procedure involves use of a specific antibody covalently attached to derivatized polyacrylamide beads and a fluorescently labeled specific antibody. Reproducible results were achieved for C3 in serum in the range of 20 mg/d1 to 195 mg/d1 within 2 h. C3 levels as low as 125 ng/m1 can also be measured. Fluorescent immunoassay and radial immunodiffusion were used to determine C3 levels in healthy adults. Good agreement was found between the two methods.

A solid phase fluorescent immunossay for the quantitation of the C4 component of human complement.

A non-competitive method for the determination of the C4 component of human complement in serum is described. This procedure involves use of a specific antibody covalently attached to derivatized polyacrylamide beads and a fluorescently labeled specific antibody. Reproducible results were achieved for C4 in serum in the range of 10 mg/dl to 170 mg/dl within 2 h. C4 levels as low as 150 ng/ml can also be measured. Fluorescent immunoassay and radial immunodiffusion were used to determine C4 levels in healthy adults. Good agreement was found between the two methods.