Natural antibody recognition of v-H-ras-induced 10T1/2 transformation.

An increasing body of evidence supports a role for natural antitumor antibodies acting against tumors in vivo. However, a role for natural antibodies (NAb) in tumor surveillance would imply that sensitivity to NAb should increase following events associated with cellular transformation. To test this prediction we examined by flow cytometry the effect on serum NAb binding of v-H-ras expression and integration in 10T1/2. The co-introduction of v-H-ras and the neomycin resistance (neor) gene into 10T1/2 followed by G418 selection resulted in a marked and heterogeneous increase in NAb binding. Clonal analysis of this population demonstrated that the increased NAb binding was associated with tumorigenic conversion and ras-p21 expression. The results provide the first evidence for a NAb-susceptible phase of ras-induced transformation.