QUANTITATION OF IGE AND CARCINOEMBRYONIC ANTIGEN (CEA) BY OPTICAL BEAM DEFLECTION (OBD) MEASUREMENT OF DOT-IMMUNOBINDING ASSAY PATTERNS VISUALIZED BY AN ELISA TECHNIQUE

Dot-immunobinding assays of IgE and CEA were performed by a convention al dot-ELISA technique with diaminobenzidine staining, and the quantit ative results were compared by densitometry and a new, spectroscopic, optical beam deflection (OBD) method using the same membrane. It was p ossible with the OBD method to detect quantities of these substances a t least ten times smaller than with densitometry. Better intra-assay r eproducibility for IgE and CEA measurements was obtained by the OBD me thod. The measurable ranges of the OBD method was broader than that of densitometry, because dark bands caused OBD in proportion to their co lor densities. When the dot-immunobinding assay with OBD measurement f or CEA was also compared with a microtube ELISA using biotin-avidin co njugates, the sensitivities and reproducibilities of the two methods w ere found to be similar, with a correlation coefficient of 0.991.