Erythrina cristagalli lectin-reactive alpha-fetoprotein-E2: a marker of hepatocellular carcinoma and other malignancies.

A newly isolated lectin Erythrina cristagalli (ECL) was tested for separation of human alpha-fetoprotein (AFP) glycoforms by affinity electrophoresis at 0.5 mg/ml and separated AFP bands were detected by antibody-affinity blotting. Three AFP bands, AFP-E1, AFP-E2 and AFP-E3 in order of increasing affinity, were obtained. Sera from control patients with chronic hepatitis and cirrhosis gave a major band of AFP-E1 and a minor or trace band of AFP-E2 (3.4 +/- 2.3%), while those from patients with mostly advanced hepatocellular carcinomas had increased proportions of AFP-E2 band (16.6 +/- 10.2%). With a cutoff level of 8% (mean + 2SD of AFP-E2 for controls), the sensitivity for hepatocellular carcinoma was 72% at a specificity of 100%. Gastrointestinal tumors had much higher percentages of AFP-E2 and occasionally positive AFP-E3. Most of the yolk sac tumors examined showed AFP-E3 in addition to AFP-E2, although AFP-E3 was a minor band. Thus, AFP-E2 is potentially a clinically useful marker for differentiation of increased AFP in hepatocellular carcinoma and other malignancies from that in precancerous chronic hepatitis or cirrhosis.