Development of an enzyme-linked immunosorbent assay for fecal bile acid.

It has been suggested that the bile acids in the feces act as a promoter of colon cancer. Among the bile acids, deoxycholic acid (DCA), which is one kind of the secondary bile acid, is said to have strong influence. DCA/cholic acid (CA) ratio in feces is also said to have a diagnostic significance in colon cancer. With this in mind, we created a CA and DCA's monoclonal antibody (MoAb) to measure them through the enzyme linked immunosorbent assay (ELISA) method. Using these MoAb, we were able to measure CA and DCA concentrations with low cross-reaction to other bile acids compared with the method with polyclonal antibody (PoAb). We measured CA and DCA concentrations and calculated the DCA/CA ratios in healthy subjects and patients with colon cancer. All subjects had been screened for colon cancer. We then compared the healthy subjects, the cancer patients before surgery and the same cancer patients after surgery. Cancer patients after surgery had significantly low DCA/CA ratios compared to before surgery, whereas there was no significant difference between healthy subjects and the pre-operative colon cancer patients.