Intestinal alkaline phosphatase: an immunoprecipitation method for the determination in feces.

An immunoprecipitation method for the determination of human intestinal alkaline phosphatase (I-AP) in feces is described using anti-human I-AP IgG. Antibodies to human I-AP are monospecific after absorption with human placental alkaline phosphatase and show no cross-reactions with human liver alkaline phosphatase or alkaline phosphatase from E. coli. Normal controls demonstrate a logarithmic normal distribution of I-AP activity in feces. The standard deviation of the intra- as well as of the inter-assay variation is 11.7%. This method represents a simple quantitative non-invasive in vivo assay for brush border damage under experimental and/or clinical conditions.