Quantitative analysis of alkaline phosphatases in serum and amniotic fluid: comparison of biochemical and immunologic assays.

An immunoprecipitation method using monoclonal antibodies specific for the three categories of alkaline phosphatases, liver/bone/kidney, placental, and intestinal, is described and compared with the heat denaturation-chemical inhibition method for quantitating the contributions of the various isoenzymes to the total activity in biologic fluids. Activity values for the three categories of isoenzymes present in normal and pregnancy sera as well as in early gestation amniotic fluids were determined by both methods. There is very close correlation between the values obtained by both methods. Thus, two independent procedures are now available for quantitating the contributions of the various alkaline phosphatase isoenzymes in biologic fluids.