Analysis of lectin affinity immunoelectrophoretic profiles of serum alpha-fetoprotein from patients with yolk sac tumors and carcinomas of the gastrointestinal tract: correlations with molecular structures

Characterization of sugar chain structures of human alpha-fetoprotein by lectin affinity electrophoresis. ibarahp@oka.urban.ne.jp

Alpha-Fetoprotein (AFP) glycoforms, defined as AFP with different chemical structures of carbohydrate, were analyzed by affinity electrophoresis with several lectins of known specificities against complex-type oligosaccharides. Serum AFP samples from cord blood on full-term delivery and from patients with hepatocellular carcinoma and extrahepatic malignancies including gastrointestinal tumors and yolk sac tumors were used. Two-dimensional lectin affinity electrophoresis and also lectin affinity chromatography coupled with lectin affinity electrophoresis were employed. More than ten AFP glycoforms were identified or characterized using the above-mentioned AFP samples. Known specificities of the lectins against complex-type oligosaccharides were refined or their additional specificities were found in this study. Lectin appeared to have specificity against carbohydrates by recognizing not only specific residues but also the whole carbohydrate molecule containing the residues, resulting in differential affinities for the lectin.

The role of subfractionation of alpha-fetoprotein in the treatment of pediatric surgical patients

Subfractionation of serum alpha-fetoprotein (AFP) is a useful method to discriminate between yolk sac tumors, hepatic malignancies, and benign liver diseases in adults but has not been validated in infants and children. AFP subfractionation was performed on AFP-positive sera from 73 infants and children. AFP subfraction profiles were classified into three common types: (1) yolk sac type, (2) hepatoblastoma type, and (3) benign hepatic type, according to the reactivity of individual AFP samples to lectins. In 68 of 73 samples (93.2%), AFP subfraction profiles were accurately classified into these three types, and an atypical AFP subfraction profile resembling the hepatoblastoma type was found in sera from five infants (6.8%). Differentiation between hepatoblastoma and hepatitis when patients are very young can be difficult. Subfractionation is more accurate when patients are older. This technique was found to be useful in the diagnosis of neonatal ovarian tumors, in recurrent hepatoblastoma/ yolk sac tumor with low serum AFP, and in the differential diagnosis of hepatic mass (malignancy versus hyperplastic nodule) in the liver with long-standing cholestasis. Estimation of serum AFP subfraction profiles facilitates the differential diagnosis of various AFP-positive pediatric diseases, such as hepatoblastoma, hepatoma, hepatitis or germ cell tumors. This test is inexpensive, can be carried out within 48 hours, and should be performed for the differential diagnosis of pediatric liver disease.

A case of ovarian serous adenocarcinoma suggestive of transformation to an AFP-producing tumor during chemotherapy

Ovarian serous adenocarcinoma with AFP production is very rare. A case involving a 66-year-old woman with an elevated serum AFP level without detectable hepatic involvement. AFP-positive cells were seen in the tumor at the second surgery. Fifty-seven percent of serum AFP from the patient bound Con A, whereas 43% did not. Similarly, 54% of the tumor fluid also bound Con A. These suggest that the serum AFP was similar to that of gastrointestinal tumors and yolk-sac tumors.

Hepatoid adenocarcinoma of the stomach. A clinicopathologic and immunohistochemical analysis

BACKGROUND

The clinicopathologic and immunohistochemical features of the primary gastric hepatoid adenocarcinomas still remain unclear.

METHODS

The authors evaluated 28 hepatoid adenocarcinomas (HC) of the stomach on the basis of characteristic histologic features resembling hepatocellular carcinoma, which were selected from the 7200 cases of primary gastric carcinoma in their files. Additionally, 22 alpha-fetoprotein (AFP)-positive adenocarcinomas without hepatoid features (APC) were also selected.

RESULTS

The HC cases fell into the following two groups: HC with AFP-positive tumor cells (Group 1; 15 cases) and HC without AFP-positive cells (Group 2; 13 cases). Histologically, the glycogen granules and hyaline globules were common features in HC. The incidence of a venous invasion of HC (Groups 1 and 2) was higher than that of APC (Group 3). There were no significant differences among the three groups regarding clinical features, macroscopic features, and the incidence of lymphatic permeation. An immunohistochemical study showed that HC had differentiation into various directions. As for the advanced carcinomas, the 5-year survival rates of patients with HC (Groups 1 and 2) and those with APC (Group 3) were 11.9% (21.4%, 8.3%) and 38.2%, respectively. The prognosis of Group 1 was similar to that of Group 2, but was poorer than that of Group 3.

CONCLUSIONS

The findings suggested that HC, as shown by its characteristic histologic features, had a poor prognosis whether producing AFP or not, and that HC should therefore be distinguished from AFP-positive carcinoma without hepatoid features.

Identification of alpha-fetoprotein-P4 sugar chain as alpha 2-->6 monosialylated biantennary complex-type oligosaccharides with an exposed galactose on the mannose alpha 1-->6 arm by two-dimensional extended agarose gel-lectin affinity electrophoresis

Erythroagglutinating phytohemagglutinin (E-PHA)-reactive alpha-fetoprotein (AFP)-P4 and E-PHA weakly-reactive AFP-P3 of sera from cord blood at term and from patients with hepatocellular carcinomas showed a mobility of monosialo-AFP in two-dimensional extended agarose gel-E-PHA affinity electrophoresis. Asialo-AFP had as high an affinity for E-PHA as that of monosialo-AFP-P4, while disialo-AFP, AFP-P2, revealed a negligible affinity for E-PHA. For Allomyrina dichotoma lectin (allo A), asialo-AFP had no affinity with a mobility of AFP-A1s, monosialo-AFP-P4 had the highest affinity with a mobility of AFP-A3, and monosialo-AFP-P3 had an intermediate affinity with a mobility of AFP-A2s. The affinity of AFP-P4 for E-PHA was reduced by galactosidase digestion, indicating the presence of galactose residues, one sialylated and the other exposed.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical applications of lectin affinity electrophoresis

Principles and several modifications of lectin affinity electrophoresis are described. The results obtained using these newly developed techniques are reviewed for individual glycoproteins, the altered lectin reactivities of which have some clinical implications, showing different lectin reactivities, which occur not only on malignant transformation but also in association with inflammatory process and hormonal action.

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%.