Immunoradiometric assay for quantitative determination of alpha-fetoprotein (AFP) in human serum or plasma
Alpha-Fetoprotein (AFP) is a glycoprotein of about 65.000 daltons molecular weight synthesized by the parenchymal cells of the fetal liver and the yolk sac. The properties and amino acid composition are similar to those of albumin. Synthesis of AFP occurs primarily in the liver and yolk sac of the fetus. The AFP level increases progressively as pregnancy progresses and reaches a peak at about the 14th week in the fetal serum and the 30th week in the maternal serum; it then progressively decreases. Elevated serum AFP levels subsequently reappear during pregnancy and in conjunction with several malignant diseases.
The RIAKEY AFP IRMA Tube II is an non-competitive immunoradiometric (IRMA) method (“sandwich”). The method employs two highly specific monoclonal anti-AFP antibodies which recognize two different epitopes of the molecule. One antibody is coated on solid phase (coated tube), the other, specific for the AFP and labeled with Iodine-125, is used as a tracer. Antibody-coated polystyrene tubes serve as solid phase. The tracer antibody and the coated antibody react simultaneously with the AFP antigen present in the standards, control serum and samples. Unbounded material is removed by a washing step. The amount of bound tracer will be directly proportional to the AFP antigen concentration and the remaining radioactivity bound to the tubes is measured in a gamma scintillation counter.