Tumor immunization of C3H.SW BMT donors induces a response to the mHAg B6^dom1 found on all C57BL/6 tumor targets tested. C3H.SW (donor strain) mice were immunized twice with 5 × 10⁶irradiated 205IL-2/TK cells (205-immune) or 20 × 10⁶ C57BL/6 spleen cells (B6-immune) at a weekly interval, or they were not immunized (naı̈ve). Ten days after the 2^nd vaccine, their splenocytes were stimulated for 5 days in vitro with C3H.SW spleen cells loaded exogenously with B6^dom1 peptide. A ⁵¹Cr-release assay was performed using the targets specified in the graphs. B6^dom1/SW CAB indicates C3H.SW ConA lymphoblast targets that were loaded exogenously with B6^dom1 peptide, whereas SW CAB were not loaded with peptide. Data shown are at an E:T ratio of 100:1, and each effector:target condition was performed in triplicate using splenocytes pooled from 2 or 3 mice. Panels A and B represent data from the same experiment.