Detection of hepatocellular carcinoma-specific alpha-fetoprotein by isoelectric focusing

Serum alpha-fetoprotein (AFP) is elevated in up to 80% of patients with hepatocellular carcinoma (HCC). Modestly raised AFP levels (10-400 ng/ml) are also found in patients with nonmalignant liver diseases. In the present study, isoelectric focusing of AFP was used to differentiate the AFP found in patients with HCC.

To establish the assay conditions, isoelectric focusing was performed on sera from 14 patients with HCC and 13 with nonmalignant liver diseases. Sera was also analyzed under coded conditions from 16 patients with HCC, 14 with chronic active hepatitis (CAH), and 6 with cirrhosis to determine the specificity and sensitivity of the assay in the diagnosis of HCC.

Isoelectric focusing of sera from patients with HCC and various non malignant liver diseases identified AFP variants (AFP I-IV). All 14 patients with HCC had AFP variants I and III, and 7 of the 14 also had variant IV. When analyzed in the coded study 13 of the 16 cases of HCC were predicted correctly by the presence of AFP variants III or III and IV. AFP bands III and IV were not discernible in 12 of the 14 patients with CAH and 4 of the 6 with cirrhosis.

Isoelectric focusing of sera from patients with HCC and nonmalignant liver disease identified two AFP variants apparently specific for HCC. In the setting of borderline elevation of AFP, this technique has a sensitivity of 81% and specificity of 85% for detecting the presence of bands III or IV and may prove suitable for use in a routine laboratory as a screening assay.