Heterophil Forssman glycoprotein and adenovirus 12: transformed rat cell lines

Immunobiological significance of Forssman (F) glycoprotein expressed on rat tumor cells derived from transfection of a fibroblast line with whole DNA (WY-3); EcoRI-C fragment, 0-16.5 map units (CY-1); and Accl-H fragment, 0-4.7 map units (HY-1) of adenovirus 12 was investigated. Culturing of F-positive WY-3 and CY-1 cells, but not F-negative HY-1 cells, with monoclonal rat F-antibody resulted in the blocking of their cell-cell adhesion and attachment to plastic surface and inhibition of their growth. Immunization of WY-3 or CY-1 tumor-bearing F344 rats with sheep red blood cells or purified F-antigen in adjuvants brought regression of the tumor in 13 of 19 rats. No such antitumor effect was observed in F-negative HY-1 tumor-bearing rats upon immunization with the F-antigens. Results of this study indicated that the membrane glycoprotein with F-epitope may play a role in lodgement of the tumor cells in vitro and serve as an in vivo target of specific immune effectors.