Serum placental type alkaline phosphatase in cigarette smokers

By means of enzyme immunoassays based on two monoclonal antibodies with specificities for distinct forms of placental type alkaline phosphatase (Pl-ALP), together with L-leucine inhibition studies, it has been possible to distinguish the Nagao type carcinoplacental enzyme from other placental type alkaline phosphatases. This approach has shown that it is the Nagao type (placental like) enzyme which is detectable in small amounts in the plasma of healthy individuals, particularly cigarette smokers.