Alpha-Fetoprotein (AFP) levels of 1,335 males (15 years and older) of seven ethnic groups (Chinese, Indians, and Malays from Singapore, Caucasians from Lyon, and Blacks from Nairobi, forest, and the savanna region of the Ivory Coast) were determined by radioimmunoassay. A few elevated levels (up to 30 nanounits/ml) were detected in some normal individuals, especially in the older age-groups. In addition, there was a systematic age-dependency of AFP levels particularly evident in the groups from Singapore-Lyon, in which there was a 50% AFP increase between the ages of 20 and 40. Comparison between Africans on the one hand and people from Singapore-Lyon on the other hand revealed highly significant differences (p less than 0.001), especially in the younger groups, whereas Chinese, Malays, and Indians from Singapore had very similar AFP pattern; this suggests an important role for environmental factors in the regulation of AFP levels. The age dependency of the presumed effect of environmental factors is in keeping with experimental data showing that young animals respond more vigorously to AFP-stimulating factors. Although the incidence of hepatocellular carcinoma (HCC) differs in the three Singapore groups (the highest in Chinese and the lowest in Indians), no relationship was observed in this study between mean AFP level and HCC incidence in Singapore.
There have been several reports on the possible value of measurements of circulating immune complexes for the diagnosis of human breast cancer. To begin to evaluate this possibility and the comparability of results among laboratories, a cooperative study was organized under the auspices of the International Agency for Research on Cancer and the National Cancer Institute (NCI) of the United States. Investigators from four laboratories performing assays for immune complexes were sent coded aliquots of serum specimens from the NCI-Mayo Clinic Serum Bank. The serum panel consisted of specimens from 30 patients with breast cancer (including 20 from untreated patients with resectable tumors), 30 preoperative patients with benign breast disease, and 30 normal women. Although some significant differences in levels of immune complexes between cancer patients and controls were seen, none of the assays had sufficient discriminatory capacity to support optimism about the diagnostic value of this approach. To relate the results with immune complexes to those with a widely used cancer marker, the same sera were also tested for levels of carcinoembryonic antigen (CEA). The CEA assay provided significant discrimination between cancer patients and normal donors but did not significantly discriminate between malignant and benign breast diseases.
With the use of membrane immunofluorescence and xenogeneic antisera, tumor-specific membrane antigens were detected on rat epithelial-like liver cells transformed in vitro by chemical carcinogens. These antigens were not detected in 10-, 15-, and 19-day rat fetuses. Xenogeneic antisera were produced in rabbits by immunization of the rabbits with cultivated BD rat liver cells transformed by dimethylnitrosamine or N-methyl-N'-nitro-N-nitrosoguanidine. The specific antisera against tumor-associated antigen(s) were obtained by in vivo absorption in syngeneic male rats and by in vitro absorption with various cell lines. One tumor-specific individual antigen and two tumor-specific cross-reacting antigens were shown to be present on the surface of chemically and/or spontaneously transformed rat liver cell lines. They were not detected on liver and spleen cells of normal BD adult rats, on fetal liver cells, or on liver and intestinal carcinoma cells of Wistar rats. Sera from multiparous pregnant rats had no antibodies against these tumor antigens (although they reacted with fetal cells).
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