Circulating epoxide hydrolase immunodeterminants in rats bearing hyperplastic nodules induced by 2-acetylaminofluorene

Epoxide hydrolase immunodeterminants (EH-immunodeterminants), as measured by a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA), were detected in the sera of rats bearing hyperplastic liver nodules induced by feeding 2-acetylaminofluorene (2-AAF), while they were low or absent (< 0.05 μg/ml) in the sera of rats fed a basal diet. The levels of EH-immunodeterminants ranged from 0.2 μg/ml to 2 μg/ml of serum and correlated ( P < 0.01) with the nodular status of the liver. Rats with predominantly small nodules (< 3 mm) had circulating levels of antigen from 0.15 to 0.35 μg/ml while those with large nodules (> 3 mm) had values ranging from 0.4 to 2.0 μg/ml serum and the serum levels for rats containing both small and large nodules were found to be in the intermediate range (0.2–0.8 μg/ml). EH-immunodeterminants were also released into tissue culture medium from incubated hyperplastic nodule slices and the levels of the immunodeterminants released from nodules were about 5-fold higher than that released from incubated control liver.