Alpha-fetoprotein-lectin binding as a marker of tumour activity or liver damage

To establish whether alpha-fetoprotein (AFP) produced in the early post-treatment phase of a patient with a germ cell tumour of the testis or the ovary originates from the tumour or is due to an underlying disturbance in liver function, the binding of AFP to concanavalin A (Con A) was investigated as a discriminative variable. A two-step assay is described that can distinguish the type of AFP produced at levels as low as 10 ng/ml. A Con A-binding ratio of 12-43% was found in the patients with disseminated germ cell tumours and in patients with AFP-positive gastrointestinal carcinomas. AFP from the liver gives ratios below 10%.