[Interspecific embryonic antigens in the blood serum of cancer patients].

Synthesis of animal embryonic proteins in human tumors, i.e. a phenomenon of interspecific embryonal reversion is discussed. Two new interspecific embryonic antigens (IEA) with relative molecular weights of 80,000 +/- 10,000 dalton (IEA-1) and 36,000 +/- 10,000 dalton (IEA-2) were identified, using antisera obtained by immunization of rabbits with a protein fraction isolated from glycoproteins of amniotic fluid of cattle fetuses. These proteins were detectable in blood serum and amniotic fluid of cow, sheep and pig fetuses and were not in human fetus. An immunoenzymatic method was used to identify IEA-1 in blood serum in 14-20% of cancer patients and in 58% of melanoma cases. IEA-1 was not detected in blood serum of non-tumor patients. IEA-2 was identified in 21-22% of tumor and non-tumor patients.