The distribution of polyamine oxidase activity in the fetomaternal compartments

Polyamine oxidase activity was measured in different compartments of the feto-maternal unit by a radiochemical method. The activity in the retroplacental serum (mainly of intervillous origin) was 20 to 30 times higher than in maternal uterine or peripheral venous blood sera. No activity was found in the fetal cord blood sera. The enzyme level in the maternal peripheral sera fell to undetectable levels within 72 hours post partum. Preliminary data indicate that the enzyme might be produced by the decidua rather than by the placenta. It is suggested that the enzyme may constitute an important part of a supposed local immunological barrier formed at the placental bed to help to protect the fetal allograft from maternal immune rejection through a local suppressive effect on maternal cellular immunity.