Immunofluorescent localisation of human pregnancy-specific β-globulin in placenta and chorioepithelioma

Abstract

VARIOUS immunological methods have been used to define the existence on plasma of several pregnancy-associated macromolecules^1–3, of which between three and five are now well recognised in humans^4,5. The cells and tissues responsible for their synthesis, however, remain to be clearly defined, although, of the two pregnancy-associated β₁-globulins, one was recently detected in the sera of patients bearing trophoblastic tumours⁶. This particular β₁–globulin does not resemble any known hormone, including chorionic gonadotropin⁷, but seems to be identical with the pregnancy-specific β₁-glycoprotein of Bohn⁹ and the PAPP-C described by Lin et al.⁵. The placenta has been suggested as the site of its synthesis^8,9. Using indirect immunofluorescence, we have now located this β₁-globulin in human placenta and chorioepithelioma of the uterus, where we believe it is synthesised.