Efficiency of Ber-EP4 antibody for isolating circulating epithelial tumor cells before RT-PCR detection

We compared the efficacy of 4 methods for isolating circulating tumor cells : immunocapture with Ber-EP4-coated magnetic beads, density gradient separa tion, ammonium chloride, and distilled water-mediated erythrocyte lysis. Hu man blood from healthy volunteers was mixed with serial dilutions of prosta te (LNCaP) and liver (HepG2) derived tumor cells. Isolation of circulating tumor cells was followed by reverse transcriptase-polymerase chain reaction with primers specific for prostate-specific antigen and a-fetoprotein. Ber -EP4 antigen expression was evaluated by immunohistochemistry in 27 hepatoc ellular carcinomas and 34 prostate adenocarcinomas. Peripheral blood sample s from 12 patients with hepatocellular carcinoma and 10 with prostate adeno carcinoma also were rested. Density gradient separation and Ber-EP4 immunoc apture were the most sensitive techniques for isolating circulating amor ce lls in in vitro tests. isolation by density gradient separation was signifi cantly more sensitive than Ber-EP4 immunocapture when applied to peripheral blood samples of patients with cancer a result consistent with the variabl e expression of Ber-EP4 antigen that we found by immunohistochemistry in pr ostate adenocarcinomas and hepatocellular carcinomas.