Developmental Alterations of α-Fetoprotein Sugar Chain in Amniotic Fluids Analyzed by Lectin Affinity Electrophoresis

Affinity electrophoresis of human alpha-fetoprotein (AFP) in amniotic fluid from pregnant women between 6 to 42 weeks of gestation and in the serum of a yolk sac tumor was performed with concanavalin A (Con A), lentil lectin (LCA), erythroagglutinating phytohemagglutinin (E-PHA) and Allomyrina dichotoma lectin (allo A). Separated AFP bands were detected by sensitive antibody-affinity blotting. In the first trimester, amniotic fluid AFP showed elevated percentages of Con A-nonreacting AFP (AFP-C1) and LCA weakly-reacting AFP (AFP-L2) as previously reported. Additionally, high percentages of E-PHA strongly-reacting AFP (AFP-P5) and E-PHA-reacting AFP (AFP-P4) were observed. E-PHA-nonreacting AFP (AFP-P1), E-PHA weakly-reacting AFP (AFP-P3f), allo A-nonreacting AFP (AFP-A1) and asialo-AFP, AFP-A1 s, were present only in amniotic fluids from 6 to 17 weeks of gestation. With advancing gestation, percentages of AFP-C1, AFP-P4 and AFP-P5 decreased and AFP-L2, AFP-P3f, AFP-A1, and AFP-A1 s disappeared by the end of 18 weeks. The glycoforms of serum AFP of the yolk sac tumor resembled those of amniotic fluid AFP in the early gestational stages.