A two-site monoclonal enzyme immunoassay for pregnancy-associated alpha 2-glycoprotein

A two-site monoclonal enzyme immunoassay (MEIA) was developed for the determination of pregnancy-associated alpha 2-glycoprotein (PA alpha 2G) in serum. The minimum detectable level was 35 ng/ml. No immunochemical interaction with the closely related alpha 2-macroglobulin was found. Serum levels in 145 normal healthy males and non-pregnant females were 1.8 +/- 2.8 micrograms/ml (mean +/- SD), respectively, both significantly lower than previously reported. The distribution in the normal population was characteristically different when males and females were compared. No increase with age was found. During pregnancy, a significant increase in serum concentration was observed with average levels of 320 +/- 200 micrograms/ml at term (mean +/- SD), a 50-fold increase in concentration. As a tumor marker for breast and ovarian cancer, PA alpha 2G was found to be of no value. The present study emphasizes that a reevaluation of PA alpha 2G levels must be undertaken in order to assess the clinical and biological significance of this protein.