FLOW CYTOMETRIC METHOD TO MEASURE UREA-RESISTANT ALKALINE-PHOSPHATASEFROM BLOOD NEUTROPHILS FOR USE IN THE PRENATAL SCREENING OF DOWNS-SYNDROME

The histochemical measurement of urea-resistant alkaline phosphatase f rom maternal blood neutrophils is known to have a high detection rate for the prenatal detection of Down's syndrome pregnancies. However, be cause the histochemical method is laborious and subjective to use, it has not gained widespread acceptance in prenatal screening programmes. We present a simple and objective method for the measurement of urea- resistant alkaline phosphatase by flow cytometry. The method should al low the design of larger studies aimed at evaluating the role of neutr ophil urea-resistant alkaline phosphatase in the prenatal screening fo r Down's syndrome.