Figure 4.

Horizontal transfer of tumor immunity by adoptive transfer of T lymphocytes. CD8⁺ T cells were isolated from C57BL/6J mice successfully immunized with pUb-M DNA vaccine or pUb-V empty vector control. All donor animals were killed 1 week after tumor cell challenge, and their CD8⁺ T cells were isolated from their pooled splenocyte suspensions. At 48 h before i.v. challenge with 1 × 10⁵ wild-type B16G3.26 cells, naïve syngeneic SCID mice were reconstituted with a total of 4.5 × 10⁷ CD8⁺ T cells by i.v. injection of 1.5 × 10⁷ T cells on days −3, −1, and +3. Tumor growth was analyzed in mice receiving CD8⁺ T cells either from animals vaccinated with pUb-M (┌) or pUb-H (▴) or from mice vaccinated with the empty vector control (●). Tumor growth was determined by microcaliper measurements, and tumor volume was calculated according to 0.5 × width² × length.