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Lectin-affinity electrophoretic separation of serum alpha-fetoprotein (AFP) was carried out using AFP Differentiation Kits, which used Lens culinaris agglutinin-A (Kit L) and erythroagglutinating phytohemagglutinin (Kit P). Separated AFP bands were detected with a sensitive antibody-affinity blotting technique and determined quantitatively by densitometry, and the results were expressed as percentages of the intensity of total AFP bands. Sera from 424 patients with acute hepatitis, chronic hepatitis, liver cirrhosis, hepatocellular carcinoma, and extrahepatic tumors were assayed for proportion of AFP present as Lens culinaris agglutinin-A-reactive AFP (AFP-L3) and erythroagglutinating phytohemagglutinin-reactive AFPs (AFP-P4+P5). From the maximum Youden indices determined, cutoff levels were set at 15% for both AFP-L3 and AFP-P4+P5 to discriminate between patients with chronic hepatitis and liver cirrhosis and patients with hepatocellular carcinoma. AFP-L3 and AFP-P4+P5 showed sensitivities of 55.3 and 61.0% at specificities of 93.9% and 82.3%, respectively. Thirty-eight % of tumors that measured less than 20 mm in diameter were positive for AFP-L3 and AFP-P4+P5. AFP-L3 exceeded the cutoff level of 15% 4.0 +/- 4.9 months before detection of hepatocellular carcinomas by imaging techniques with a sensitivity of 48% and a specificity of 81%. Thus, these tests are useful for the early detection of hepatocellular carcinomas in patients with hepatitis or liver cirrhosis.

Serum alpha-fetoprotein (AFP) from cord blood and from patients with hepatitis, cirrhosis, hepatocellular carcinoma, gastrointestinal tumors and yolk sac tumor was analyzed by extended agarose gel electrophoresis coupled with our sensitive detection method of antibody-affinity blotting. AFP was separated into AFP-A, AFP-B and AFP-C from the anode to the cathode, corresponding to disialo-, monosialo- and asialo-AFP, respectively, as revealed by the results of neuraminidase digestion of serum AFP. AFP-Af, which migrated ahead of AFP-A as band or leading smear and varied widely in intensity, was eliminated in calculating the proportions of other band intensities. Disialo-AFP was the major component and monosialo-AFP the minor one in benign conditions, the latter being 4.2 +/- 6.0% in chronic hepatitis and 9.0 +/- 8.9% in cirrhosis. Monosialo-AFP in hepatocellular carcinoma was increased significantly, the proportion being 29.9 +/- 11.2%. AFP in other malignancies was further characterized by the appearance of asialo-AFP.