A new competitive enzyme linked immunosorbent assay (MRP83-CA15-3) for MUC1 measurement in breast cancer.

A new competitive enzyme linked immunosorbent assay was developed in this study. Monoclonal antibody (PR81) against the tandem repeat of the core protein was prepared, characterized, purified, and conjugated to HRP. This antibody exhibited no cross reactions with proteins such as bovine serum albumin, keyhole limpet homocyanin, human serum albumin, casein, human milk fat globin (HMFG), and peptone. The native cancerous MUC1 protein was purified from ascites fluid of a patient suffering from small cell lung carcinoma by immunoaffinity chromatography and used as a standard preparation in the assay buffer. The standard curve was constructed following a competitive procedure in the range of 0-200 U/mL. The level of MUC1 in normal and cancerous samples was compared following this procedure and using available CA15-3 EIA (Can Ag), as well as LIAISON CA15-3 commercial kits. The correlation coefficient between the procedure reported in this work (MRP83-CA15-3) and CA15-3 EIA (Can Ag) was 0.68 and was 0.95 with the LIAISON CA15-3 kit. We concluded that the present assay can detect MUC1 in breast cancer patients with great sensitivity and accuracy.