Placental protein 14 induces apoptosis in T cells but not in monocytes

Substantial evidence exists in literature to suggest that placental protein 14 (PP14) (recently renamed glycodelin A), exhibits immunosuppressive properties and is an indispensable macromolecule in the maternal system for the establishment, maintenance, and progression of pregnancy. Though there are several reports substantiating the above, the mechanism of its action at the molecular level has not been elucidated as yet. In this paper we provide data that suggest that amniotic fluid PP14 and recombinant PP14 expressed in Pichia pastoris induce apoptosis in human peripheral blood lymphocytes upon activation, independent of monocytes. That PP14 has a direct apoptotic action on T cells but not on monocytes was also demonstrated by utilizing human cell lines. PP14 was shown to induce apoptosis in the human T cell lines, Jurkat and MOLT-4 cells, but not in the human monocytic cell line, U937.