CLINICAL RELEVANCE OF ALPHA-FETOPROTEIN MICROHETEROGENEITY IN ALPHA-FETOPROTEIN-SECRETING TUMORS

The importance of the oncofetal glycoprotein antigen alphafetoprotein (AFP) as a tumor marker is well documented. Structural heterogeneity o f AFP molecules due to its associated carbohydrate moieties has also b een demonstrated. In the present study, molecular variants of AFP, Con canavalin A reactive (R Con A) and Concanavalin A nonreactive (NR Con A) were quantified in five cases of hepatocellular carcinoma (HCC), th ree cases of hepatoblastoma, five gonadal and two extragonadal germ ce ll tumors, and two suspected Liver secondaries by employing crossed im munoaffino electrophoresis (CIAE). AFP peaks were localized using anti -AFP antibodies conjugated to alkaline phosphatase. Characteristic pat terns of AFP R Con A and NR Con A fractions were obtained in different AFP-secreting malignancies. Serum samples of HCC and hepatoblastoma w ere predominantly composed of R Con A AFP, while gonadal and extragona dal germ cell tumors showed significant reduction of R Con A AFP and e levation of NR Con A AFP. Analysis of AFP variants in sera from two pa tients of suspected liver metastasis with elevated AFP confirmed liver secondaries arising from germ cell tumor in one patient and HCC in th e other patient. The present study highlights the importance of AFP mi croheterogeneity analysis not only as diagnostic aid for the different ial diagnosis of AFP-secreting tumors, but also in providing better ma nagement and prognosis.