Genetic variants of placental alkaline phosphatase as detected by a monoclonal antibody.

Human placental alkaline phosphatase (PLAP) is a highly polymorphic enzyme. Several common as well as rare allelic forms of PLAP are characterized in this paper in terms of their reactivity with a murine monoclonal antibody (F11). The common type 1 (S) and 3 (I) variants, and the rare type 4 (S2) and 18 (D) variants were found to react with the F11 antibody, so as did three new electrophoretically defined variants (19, 20, and 21). In contrast, the common type 2 (F1) variant and the rare type 8 (F3) and 9 (F2) variants do not react with the F11 antibody. This selective reactivity of F11 has also allowed the identification of two molecular variants of PLAP with identical electrophoretic mobility. These results establish monoclonal antibodies as invaluable adjuncts in the study of PLAP polymorphism.