CA 125 is released by human amnion cells in culture.

CA 125 was measured in the medium of human amnion cells in primary culture after confluence. The antigen accumulated as a function of time with a median value of 1897 U/mg protein after 7 days in culture. CA 125 was detectable by immunoperoxidase staining in the cells, which supports the possibility that amnion cells play a role as a source of the CA 125 found in the amniotic fluid.