Serum antibody response to Opisthorchis viverrini antigen as a marker for opisthorchiasis-associated cholangiocarcinoma.

The liver flukes Opisthorchis viverrini and Clonorchis sinensis chronically infect over 30 million people in south-eastern Asia, resulting in significant morbidity and a predisposition to cholangiocarcinoma (CCA). Liver fluke-associated CCA carries a poor prognosis, partly because it is often detected at a late and advanced stage. The development of improved diagnostic methods, particularly for early CCA, may improve chances of survival and cure. Accordingly, we explored the use of immunological responses to liver fluke antigens as a potential means of identifying individuals at high risk for liver fluke-associated CCA. Serum antibody responses to O. viverrini adult worm homogenate and metacercaria homogenate (MH) were studied using enzyme-linked immunosorbent and immunoblot assays in 65 infected residents of an opisthorchiasis-endemic area in Thailand. Antibody levels correlated with liver ultrasonography (U/S) findings, and immunoblot analysis revealed a 91/93 kDa MH doublet recognized only by sera of individuals with severe liver U/S findings, including CCA. These results suggest that serum antibody responses to liver fluke antigens may be useful in the identification of infected individuals who are at high risk for liver fluke-associated CCA.