Rat alpha-fetoprotein: isolation, radioimmunoassay and fetal-maternal distribution during pregnancy

Abstract

Summary. A method is described for the isolation of mg quantities of two forms of rat alpha-fetoprotein (AFP) from amniotic fluid by preparative disc-gel column electrophoresis using a continuous elution system. AFP isolated by this method is suitable for use as an antigen, can be labelled for use in a radioimmunoassay and serves as a reference standard. The characteristics of a new antiserum to AFP are also described.The protocol for a radioimmunoassay is outlined which permits the measurement of AFP in several fetal\p=n-\maternalphysiological compartments throughout gestation. Levels of AFP in fetal liver and fetal plasma suggest that secretion of AFP from liver occurs soon after synthesis with minimal hepatic storage. The pattern for AFP in maternal serum parallels that observed in amniotic fluid and fluctuations in maternal serum levels of AFP appear to be buffered by AFP accumulation in amniotic fluid. Fetal clearance of AFP under normal conditions may be relatively constant from Days 11\p=n-\20of gestation since an amniotic fluid : maternal serum AFP ratio of 30:1 is maintained during this period.

Rat alpha-fetoprotein in experimental utero-placental ischaemia

“…The AFP level in maternal plasma of animals in Group 2 after partial occlusion of the uterine arteries remained only slightly elevated until 48 hr after surgery when it more closely paralleled the level observed in sham-operated control rats. Plasma AFP in hysterectomized rats (Group 3) decreased steadily with a half-life of approximately 27 hr between 24 and 72 hr after surgery, and the pattern of maternal plasma AFP levels during pregnancy in the sham-operated controls (Group 4) was similar to that previously reported for normal pregnant rats (Lai et al, 1976).…”

“…Plasma (10-20 µ ) was stored at -20°C in 1 ml 005 M-phosphate buffer (pH 7-5) containing 0-5% bovine serum albumin. Radioimmunoassay of plasma AFP was as previously described (Lai et al, 1976). The rats were asphyxiated with carbon dioxide on Day 20 ofgestation and each live fetus and placenta was removed and weighed.…”

“…Feto-maternal transfer of radiolabelled rat AFP occurs via amniotic fluid and the placenta (Sell & Alexander, 1974). We have recently established the normal gestational pattern for rat AFP in fetal liver, fetal plasma, amniotic fluid and maternal serum using a radioimmunoassay (Lai, Forrester, Hancock, Hay & Lorscheider, 1976).…”

Distribution of bovine fetuin and albumin in plasma, allantoic and amniotic fluids during development

“…For example, one protein associated with fetal development and studied in detail in several mammalian species including the cow has been alpha,-fetoprotein (Branch, 1972;Lai, Forrester, Hay, Hancock & Lorscheider, 1976; …”

Attempts to Suppress Experimental Allergic Encephalomyelitis in Rats with Alpha Fetoprotein

“…It is interest ing that Alpert et al [13] have indicated that they believed the immunosuppressive effects of human fetal and tumor serum were due to factors other than AFP since the purified protein had no activity. However, the plasma of pregnant rats, which at term con tains about 4.3 mg% AFP and which is ap proximately 100 times more than is present in human plasma at a similar stage of preg nancy [27,28], did not suppress the develop ment of EAE. The amount of rat AFP present in the 600 pi of the pregnant rat plasma administered every 2nd day would have been approximately 25 pg.…”