Biological and clinical significance of pregnancy-associated alpha2-glycorprotein (alpha/-PAG)-a review.

Pregnancy-associated alpha2-glycoprotein (alpha2-PAG) is well-characterized high molecular weight human plasma protein detectable in normal individuals of both sexes. Circulating levels are related to sex and age and are increased following administration of oestrogens and in pregnancy. While alpha2-PAG production during gestation is dependent on a functional foeta-placental unit it is leucocyte-derived, although perhaps not exclusively so. There have been several reports of raised alpha2-PAG levels in a variety of malignant conditions, although this finding has been disputed. Further controversy exists over the true value of alpha2-PAG measurements in monitoring the course of malignant disease. The exact function(s) of alpha2-PAG is uncertain but there is considerable evidence that it is a non-specific immune suppressant.