Determination of the pulmonary surfactant-associated protein SP-B in amniotic fluid with a competition ELISA.

A competition ELISA was developed with polyclonal chicken antibodies, with which the surfactant-associated protein B (SP-B) can be measured in amniotic fluid. The SP-B content from 240 amniotic fluid samples taken from uncomplicated pregnancies between the 29th and 42nd week of gestation was determined. The SP-B content rose from the 33rd week of gestation onwards to a median level of 800 ng SP-B/ml amniotic fluid at the end of the pregnancy. In the 3 cases examined up to now of infants with a respiratory distress syndrome the levels lay below 300 ng SP-B/ml.