[Establishment of immuno-PCR technique for the detection of tumor associated antigen MG7-Ag on the gastric cancer cell line].

The gastric cancer associated antigen McAb MG7-Ag was detected by means of a newly established method, termed immuno-PCR. A McAb-recombinant DNA chimeric molecule was made which possesses bispecific binding affinity for antigen that had been immobilized on microtiter wells and the segment of the attached DNA was amplified by PCR. The antigen of gastric cancer cell line KATO III was monitored by this method. Analysis of PCR products by agarose gel electrophoresis after staining with ethidium bromide allowed as few as 20 cells to be detected readily and reproducibly. Immuno-PCR showed a 10(4) enhancement in detection sensitivity compared with ELISA assay. When the same numbers of cells (2 x 10(6)/ml) were immobilized and then the serial diluted chimeric molecule was added, 3.8 x 10(-14) moles and 3.0 x 10(-11) moles were needed to give positive results with the immuno-PCR and ELISA assay, respectively. Therefore, immuno-PCR could give an enormous amplification capability with good specificity, and has a sensitivity much higher than any existing techniques for antigen detection.