Radioimmunoassay of Porcine Alpha Fetoprotein

Abstract

The development of a radioimmunoassay for porcine .alpha.-fetoprotein (AFP) is described. Antibodies to AFP were produced in rabbits by injecting polyacrylamide gel slices containing AFP. AFP was purified from amniotic fluid by ion exchange chromatography and preparative polyacrylamide gel electrophoresis. AFP prepared in this manner was estimated to be > 95% pure and was suitable as a reference standard for radioimmunoassay. The radioimmunoassay was sensitive over a range of 0.6-34 ng. Levels of AFP in chorionic and amniotic fluids from 40 day old fetal pigs from 8 sows were 171 .+-. 24 and 256 .+-. 20 .mu.g/ml, respectively. Maternal serum levels were 16 .+-. 2 ng/ml at estrus and did not show a significant increase until Day 35 (23 .+-. 2 ng/ml) of gestation. From Day 50-110 of gestation, maternal serum levels of AFP were highest at Day 70 (58 .+-. 14 ng/ml); the values at this stage of gestation were quite variable, ranging from 21-180 ng/ml. Serum levels of AFP in boars were 16 .+-. 2 ng/ml and this AFP behaved identically upon ion exchange chromatography to the AFP in a mixture of sera from boar and newborn pigs. The assay described provides a basis for determining correlations between AFP levels in fetal-maternal compartments and fetal survival and maturity in swine.