Specific Complement-Fixing Tumor Antigen in SV 40 -Trans formed Human Cells. ∗

Abstract

The presence of a specific complement-fixing (CF) antigen in SV₄₀-induced tumors and in SV₄₀-transformed cells was demonstrated by Black et al(1) through the use of serum antibodies produced in SV₄₀ tumorbearing hamsters. The same antigen was shown to be present not only in hamster tumors but in hamster, rabbit, mouse, pig and bovine cells “transformed” by SV₄₀ virus in vitro, and their experimental findings suggested that this CF antigen was not identical to structural antigens of the virus. However, its specificity indicated that the information for the CF antigen might come from viral genome in the transformed cells.

Using the same serological test system we have demonstrated the same specific CF activity in human cells transformed in vitro by SV₄₀ and shown that this character is stable after transplant passage through human volunteers. Sera of these volunteers obtained before and after transplantation were tested for the presence of CF antibodies against hamster SV₄₀ tumor antigen with negative results, although several of the human sera had demonstrable CF antibodies against an antigen present in normal hamster tissues.

Materials and methods. Antigens. Tumors or cells harvested from tissue culture were made up to 10-20% suspensions in veronal buffer, kept frozen at — 50°C and used as such. For titrations of antibody, standard suspensions of a transplantable SV₄₀ hamster tumor(2) were used at dilutions containing 4-8 units of CF antigen.

Antisera. All sera were inactivated at 60°C for 20 minutes. For titration of antigens a single positive hamster serum pool was used at a 1/32 dilution representing 4-8 units of CF antibody. This serum was negative when tested against hamster tumors produced by polyoma, adeno 12 and adeno 18 viruses, and SV40 virus antigen.

CF test. Standard Bengston procedure using 0.2 ml amounts of each ingredient was used with 2 full units of guinea pig complement and fixation overnight at 4°C.