Decidual protein synthesis and its clinical significance.

In vitro cultures of the endometrium during the cycle and in early pregnancy have been studied. Using a radiolabelled amino acid synthesis and secretion of protein by the endometrium during different phases of the menstrual cycle and pregnancy have been characterised. De novo synthesis and secretion of at least 17 endometrial proteins have been demonstrated. The effect of progesterone on synthesis and secretion has been observed and the proteins have been classified according to their association with different phases of the cycle and the effect of progesterone. The principal protein synthesized and secreted by the secretory and early pregnancy endometrium has been purified and characterized. It is a glycoprotein (molecular weight 56 KD) with a2-mobility and has been named a2-pregnancy associated endometrial globulin (a2-PEG). As the tissue content and rate of production of a2-PEG were greatest in tissues containing a predominence of secretory glands it is suggested that the glandular epithelium is the source of a2-PEG. A radioimmunoassay to a2-PEG has been developed and the normal levels of a2-PEG have been obtained throughout pregnancy both in the amniotic fluid and in the peripheral serum. The prognostic value of screening for a2-PEG during the first trimester of pregnancy has been assessed in a number of clinical situations. The sensitivity, specificity and predictive values of an abnormal result in threatened abortion, ectopic pregnancy, pregnancy induced hypertension, preterm labour and intrauterine growth retardation have been established. Elevated levels of a2-PEG are found in association with many cases of proteinuric pregnancy induced hypertension and intrauterine growth retardation. Depressed levels are found in association with non-proteinuric hypertension and ectopic gestation and essentially normal levels in patients with threatened abortion. The significance of these results is discussed.