Development of a radio-immuno-assay for oxytocin.

High affinity antibodies against oxytocin were produced by multiple intradermal injections. The antibodies do not cross react with lysine vasopressin. Reduction of the S-S link changes the immunoreactivity. The high affinity constant of the antibodies allows direct RIA of oxytocin in diluted plasma (1:5), with a sensitivity of at least 4 muU/ml. Preliminary results for oxytocin determination in human umbilical cord plasma range between 15 - 100 muU/ml.