Diamine oxidase activity in human maternal and fetal plasma and tissues at parturition

The human maternal-to-fetal plasma diamine oxidase (DAO) ratio was measured in 48 paired samples from full-term pregnancies. A radioassay procedure was employed. The over-all mean maternal-to-fetal (M/F) ratio was 166/1. In a series of 12 premature deliveries the mean M/F ratio was 21/1. The low M/F ratio in the latter group was due to a high mean plasma DAO titer in the premature infants. The relative DAO content of the various trophoblastic and decidual tissues and fluids at parturition in decreasing order of activity, were as follows: decidua = 5,200, membranes = 4,100, placenta = 1,400, amniotic fluid = 100, maternal plasma = 42, cord = 14, and fetal plasma = 1. The accumulated data support the concept of a decidual origin of pregnancy DAO.

radioassay of diamine oxidase; prematurity; trophoblastic and decidual tissues; amniotic fluid

Submitted on September 2, 1964