Changes in alpha 1-acid glycoprotein serum concentrations and glycoforms in the developing human fetus.

alpha 1-Acid glycoprotein concentrations and reactivity to concanavalin A were measured in maternal and fetal serum and amniotic fluid obtained from 24 women undergoing diagnostic cordocentesis at 20 to 33 wk gestation and in 30 additional fetal sera (19 to 34 weeks gestation). Maternal alpha 1-acid glycoprotein serum levels were five to ten times higher than fetal and amniotic levels. Fetal alpha 1-acid glycoprotein levels were found to increase with advancing gestational age. Using crossed immunoaffino electrophoresis with concanavalin A, alpha 1-acid glycoprotein patterns were identical in maternal serum and amniotic fluid but totally different in fetal serum. The fetal concanavalin A pattern changed progressively during fetal life towards that of the newborn. These data confirm earlier assumptions of fetal synthesis of alpha 1-acid glycoprotein and provide normal reference values for alpha 1-acid glycoprotein in fetal serum. In addition, the specific fetal concanavalin A pattern indicates that the alpha 1-acid glycoprotein glycosylation process during fetal life differs from that in post-natal life.