Enzyme immunoassay of motilin in human plasma.

A sensitive and specific double-antibody enzyme-linked immunoassay (EIA) for detecting a motilin-like immunoreactive substance (M-IS) in human plasma has been developed. In competitive reactions, the motilin antibody was incubated with a plasma sample (or motilin standard) and β-D-galactosidase-linked synthetic motilin. Free and antibody-bound enzymes were separated using an anti-rabbit IgG-coated immunoplate. Enzyme activity on the plate was determined by fluorophotometric analysis. This immunoassay allows the detection of 20 to 200 fmol/ml (54 to 540 pg/ml) of motilin. The mean level of M-IS detected in human plasma was 53.9±25.6 pg/ml.