Some intraspecies differences in antigens on the surface of certain living human cells

Surface antigens of several types of living cells of human origin were partially characterized with hyperimmune antisera prepared in the rabbit against living HeLa cells and living, uncultured, full-term, human amnion cells. Hemagglutination, mixed-agglutination, and direct and indirect immunofluorescence (FAB) techniques were employed. With these techniques and fractional absorption procedures, common and specific cell antigens were detected on the surface of several human living cells: uncultured and primary amnion, two established human cell lines (RP Am 1 and U amnion) of presumed normal origin and two (HeLa and HEp-2) of presumed malignant origin, and human erythrocytes. None of the antigens were found on NCTC 2555 mouse cells. The human cells possessed species-related antigens demonstrable by hemagglutination. After removal of the hemagglutinins by absorption with human erythrocytes, antibody in high titer for the homologous cells was detected by FAB methods. In addition, some changes in antigens on the surface of amnion cells during primary culture were observed. Finally, an antigen was found on HeLa and HEp-2 cells, by use of anti-HeLa serum absorbed with human erythrocytes and RP Am 1 cells, that was not found on either human erythrocytes, uncultured amnion cells, or on the cells of the two established amnion cell lines. At the dilutions used in the tests, antibodies to the ABO blood group isoantigens, Forssman hapten, or adsorbed serum proteins could not account for the antigens detected. The possibility that Mycoplasma sp. antigens were responsible for the reactions was inconsistent with the results. The specificity of the FAB methods on living cells was confirmed.