Novel plasma extraction procedure and development of a specific enzyme immunoassay of oxytocin: application to biological and clinical investigations of small-cell carcinoma of the lung

摘要

Paraneoplastic secretion of the lactation-inducing hormone oxytocin (OT) has been reported in about 30% of cases of small cell carcinoma of the lung (SCCL). In order to investigate the role of OT in the biology of SCCL tumours, a specific enzyme-immunoassay(EIA) for OT, which can be applied to both human plasmaand culturemedium, has been developed. OT EIA is performed on 96-well microtiter plates coated with a rabbit polyclonal antibody (Ab) anti-OT (O4). This antibody does not exhibit any significant cross-reactivity either with vasopressin (VP) or with vasotocin (VT). The immunological reaction involving Ab anti-OT is a competition between the tracer (biotinylatedOT) and syntheticOT (standard curve) or OT present in biological samples. In order to limit interference induced by plasma proteins, plasma samples are titrated by a one-step centrifugation on centricon YM-3 (cut-oOE 3000 Da). After plasma filtration, 90.7 ± 5.1 (SD) % (n = 22) immunoreactive ( IR) OT is recovered. The sensitivity of OT EIA is 1 pmol/L, while intra- and inter-assay coefficients of variation (CV) are around 3.41% and 2.84%, respectively. In healthy volunteers, plasma IR OT is 7.28 ± 4.49 (SD) pmol/L (n = 32) with no gender diOEerence. As shown by the data both from plasma of SCCL patients and from supernatants and cell contents of SCCL cell lines, this EIA procedure offers a novel, reproducible, specific and sensitive method for the measurement of IR OT.