Sequential fluoroimmunoassay for measurement of pregnancy specific beta 1 glycoprotein using antibody coupled to magnetisable particles.

A direct, sequential fluoroimmunoassay has been developed for the determination of serum levels of pregnancy specific beta 1 glycoprotein (SP1). The method employs rabbit anti-SP1 serum coupled to magnetisable cellulose-iron oxide particles and fluorescein-labelled SP1. Serum samples or standards are incubated with magnetisable solid phase anti-SP1 for 30 min. After magnetic sedimentation of the particles, the supernate, which includes endogenous fluorophores and other interfering factors, is discarded. Fluorescein-labelled SP1 is then added and incubated for a further 45 min; the particles are again sedimented and the fluorescence of the labelled SP1 remaining in the supernate is estimated. This reading related directly to the SP1 content of the original sample. The entire procedure, including fluorometry, is performed within a single disposable polystyrene test tube and is sufficiently simple and reliable for routine application. The sensitivity, specificity and precision is very similar to that of radioimmunoassay, and the results correlate with those of the radioimmunoassay (r = 0.9887).

Measurement of placental protein 5, placental lactogen and pregnancy-specific beta 1 glycoprotein in mid-trimester as a predictor of outcome of pregnancy.

The circulating levels of placental protein 5 (PP5), placental lactogen (hPL) and pregnancy-specific beta 1-glycoprotein (SP1) were measured in 254 women at the 16th week of pregnancy and the levels were correlated to fetal outcome in late pregnancy. A significant association was shown between high PP5 levels and premature delivery, and low SP1 levels and intrauterine growth retardation. Measurement of placental proteins in the first half of pregnancy may be a valuable clinical index of fetal outcome in late pregnancy.

Circulating concentrations of specific placental proteins (human chorionic gonadotropin, pregnancy-specific beta-1 glycoprotein, and placental protein 5) in untreated gestational trophoblastic tumors.

Serum levels of human chorionic gonadotropin (hCG), pregnancy-specific beta-1-glycoprotein (SP1), and placental protein 5 (PP5) were measured prior to treatment in 14 patient with hydatidiform mole and in nine patients with choriocarcinoma. Measurement of circulating levels of SP1 and PP5, but not hCG, provides a distinction between benign and malignant gestational trophoblastic tumors.

Molecular heterogeneity of placental protein 5 (PP5) in late pregnancy serum and plasma: evidence for a heparin-PP5 polymer.

The apparent levels of placental protein 5 (PP5) measured by radioimmunoassay are substantially greater in serum than plasma. Using molecular sieve chromatography we have shown that PP5 exists in a number of different forms, and that in the presence of heparin or endogenous heparin-like substances PP5 forms complexes and polymers. These findings add weight to the concept that PP5 may be involved with the coagulation system and, in particular, with coagulation mechanisms in the intervillous space of the human placenta.

Immunochemical and biological studies on two molecular variants of pregnancy specific beta 1 glycoprotein (SP1) SP1 alpha and SP1 beta.

Analytical crossed immunoelectrophoresis was performed to examine the relationship of a high molecular mass alpha 2 mobile glycoprotein (SP1 alpha) which is immunochemically identifiable with pregnancy specific beta 1 glycoprotein (SP1 beta). There was no evidence for any reaction of SP1 alpha with antisera to normal human serum protein, nor for complex formation following incubation with normal serum proteins. The half-life of SP1 alpha was apparently shorter than that of SP1 beta after delivery of the placenta.

Molecular heterogeneity of pregnancy specific beta 1 glycoprotein: the effect on measurement by radioimmunoassay and electroimmunoassay.

A comparison of methods for the quantification of circulating pregnancy specific beta 1 glycoprotein in late pregnancy was performed to assess the influence of the presence of a high molecular weight glycoprotein with alpha 2 electrophoretic mobility (SP1 alpha) which is immunochemically identifiable with pregnancy-specific PBETA 1 glycoprotein (SP1 beta). Serum samples from 47 volunteers in the 3rd trimester of pregnancy were subjected to measurements of pregnancy specific beta 1 glycoprotein in rocket immunoelectrophoresis, quantitative crossed-immunoelectrophoresis and radioimmunoassay. Rocket immunoelectrophoresis gives a result which reflects the total SP1 content, i.e. SP1 alpha and SP1 beta while quantitative crossed-immunoelectrophoresis permits differentiation between the two molecules. Radioimmunoassay predominantly measures authenic SP1, i.e. SP1 beta in the presence of physiological amounts of SP1 alpha.