PROTECTIVE ANTITUMOR IMMUNITY INDUCED BY IMMUNIZATION WITH COMPLETELYALLOGENEIC-TUMOR CELLS

We have shown previously that immunization of B6 mice (H-2(b)) with tu mor cells of B6 origin transformed by the human adenovirus type 5 earl y region 1 (Ad5E1) induces an H-2D(b)-restricted CTL response against an E1B-encoded CTL epitope. We now report that immunization of B6 mice with Ad5E1-transformed tumor cells of BALB/c origin (H-2(d)), apart f rom inducing a B6 anti-BALB/c allo-response, also induces a strong CTL response against the E1B-encoded H-2D(b)-presented CTL epitope. BALB/ c Ad5E1-transformed tumor cells are not recognized by E1B-specific CTL s, indicating that nontumor cells have processed the E1B-encoded CTL a ntigen and have presented the E1B peptide to E1B-specific CTLs. These data also show that the B6 anti-BALB/c allo-response does not overwhel m the anti-E1B response induced by the allogeneic tumor cell vaccinati on. Moreover, B6 mice immunized with allogeneic BALB/c Ad5E1 cells are , in contrast to mice vaccinated with untransformed BALB/c cells, prot ected against a subsequent challenge with B6 Ad5E1-expressing tumor ce lls. These data show that immunization with completely allogeneic tumo r cells can lead to protective syngeneic antitumor immunity, indicatin g that completely allogeneic tumor cell vaccines can be used for the i nduction of antitumor immunity.