ISSN:
1365-3083
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Previous work (Brock, Lancet, 2, 197, 1972) has established that Alpha-fetoprotein (AFP) is elevated in amniotic fluid from open neuro-tubular defective pregnancies. This report describes a simple quantitative immunonephelometric method for measurement of AFP in amniotic fluid.Immunonephelometry measures the amount of light scattered by soluble antigen-antibody complexes. Complex formation is proportional to the antigen concentration, resulting in a proportional increase in light scattered. A modified Kallestad nephelometer was used for this study. It consists of a tungsten light source with a filter at 610 nm and two photodetector cells at 90° with respect to light source.The assay procedure requires mixing a 100 μl sample of amniotic fluid with 2 ml of goat anti-AFP (dilution 1:50) in 4% PEG-saline. The assay requires a 60 minute incubation at room temperature. The standard curve covers the range 773 to 21,775 I.U./ml, with a minimum detectable dose of 120 I.U./ml. Precision is good, with an interassay coefficient of variation of 〈 4% using low, medium, and high controls. Recovery of AFP added varied from 92 to 100%. The method correlates well with radioimmunoassay (r = 0.97, n = 37) and the slope is not significantly different from one (p〈0.001).In summary, our nephelometric procedure is rapid, reproducible and sensitive, offering advantages over currently employed methods.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3083.1978.tb03944.x
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