A monoclonal antibody capture assay for intestinal alkaline phosphatase and the measurement of this isoenzyme in pregnancy.

Intestinal ALP was purified from meconium to a specific activity of 1,100 U/mg protein and used as antigen in the preparation of 7 monoclonal antibodies. Two of these antibodies were specific for intestinal ALP and reacted with different epitopes. Both bound adult intestinal ALP better than fetal intestinal ALP. One of these antibodies was used to establish a capture assay for intestinal ALP in human serum over the range 0.5-16 U/l. Reference ranges of serum intestinal ALP concentrations were established in relation to blood groups. Measurement of intestinal ALP in the serum of pregnant women showed no correlation with pre-term fetal passage of meconium.