Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Abstract: Solid-phase enzyme immunoassays, based on monoclonal antibodies reactive with different forms of human placental-type alkaline phosphatases, were applied to their detection in human seminal plasma from fertile and infertile men. The placental-like form of alkaline phosphatase (PLAP-like AP), known to occur in testicular tissue, was found in normal seminal plasma. The incidence of detection and levels of this isoenzyme correlated significantly with the designated fertility status of the donor. Seminal plasma (PLAP-like AP) may reflect germ cell function and/or access of testicular products to the ejaculate.
Placental-type alkaline phosphatase in human seminal plasma from fertile and infertile men.