Shared T cell-defined antigens on independently derived tumors

We report that a subset of tumors independently derived from a cloned line of contact-inhibited, non-tumorigenic murine fetal fibroblasts confer cross-protective immunity against each other in vivo. Concordant with the in vivo cross-protection, cytolytic T cell clones from mice immunized with one of these tumor lines specifically lyse the three other lines in the same set but do not cross-react with either the nontumorigenic parental line or another similarly derived tumor line representing a different antigenic profile. This and other recent evidence for shared expression of tumor rejection Ag contrasts with the antigenic diversity previously described for chemical- and radiation-induced tumors. In the interpretation of such data it is essential to distinguish between Ag expressed in association with the transformation process and Ag induced by random mutation of already transformed cells.