The changes in CAP activity in first trimester placental chorionic villi and maternal serum, and their clinical significance.

We investigated the CAP activity of placental chorionic villi and maternal serum in the first trimester using a new ultramicro fluorometric method and obtained the following results: The CAP activity of the lysosome fraction (C3) was the greatest of the first trimester villi fractions (6.8 +/- 1.5n mol AMC/min/mg protein). No changes in CAP activity were seen in each fraction for the same wet weights of chorionic villi obtained during the different trimesters. The peak volumes (found with Sephadex G200) of the first trimester chorionic villi C3 fraction and the first trimester maternal serum almost coincided. CAP activity in normal healthy pregnant women in the 5th to 13th weeks of gestation rose gradually as pregnancy advanced. Maternal serum CAP activity was found to be lower than normal when abortion was imminent, but in cases in which the prognosis was favorable, the clinical signs, such as genital bleeding and lower abdominal pain, vanished and the values returned to within the normal range. However, when the prognosis was poor, the clinical signs did not improve and the values remained below normal. These findings suggest that first trimester CAP is produced by the lysosome fraction (C3) of the chorionic villi and that its activity in the maternal serum is directly related to placental function.