ELEVATED SERUM LEVELS OF ALPHA-FETOPROTEIN (AFP)-LIKE IMMUNOREACTIVITY IN RAINBOW-TROUT, ONCORHYNCHUS-MYKISS (WALBAUM), WITH AFLATOXIN-B1 INDUCED HEPATOCELLULAR-CARCINOMA

Alpha foetoprotein (AFP)-like immunoreactivity was detected by double immunodiffusion in the sera of adult rainbow trout, Oncorhynchus mykis s (Walbaum), with histologically confirmed hepatocellular carcinoma ex perimentally induced in microinjection of embryos with aflatoxin B1 (A FB1). Partial characterization indicated that this AFP-like immunoreac tivity gave immunologic cross-reaction of partial identity with human AFP, had alpha1 electrophoretic mobility, and an estimated molecular w eight of 72 kDa. Elevated serum AFP-like immunoreactivity levels were also measured by RIA in seven out of eight adult rainbow trout with he patocellular carcinoma, and in three out of 17 AFB1-exposed trout with out demonstrable gross or microscopic evidence for hepatocellular neop lasms. No serum AFP-like immunoreactivity was detected or measured in normal healthy age-matched DMSO-control rainbow trout. These data are consistent with the following conclusions: (1) AFP-like immunoreactivi ty detected and measured in the sera of rainbow trout with hepatocellu lar carcinoma is an analogue to human AFP; and (2) the elevated serum AFP levels measured in adult rainbow trout with hepatocellular carcino ma resemble those found in humans with this same malignancy. These dat a further suggest that serum AFP measurements might be useful to confi rm the appearance of hepatocellular carcinoma in experimental fish car cinogen-assay systems, and to detect hepatocellular neoplasia in high- risk wild fish populations exposed to carcinogenic pollutants.