Figure 8.

Function of T‐cell subsets in antitumour activity. (A) Immunogenic effect of p‐c treated tumour cells. BALB/c mice were injected into one flank with 1 × 10⁶ p‐c treated CT26 tumour cells and into the opposite flank with 2 × 10⁵ live CT26 cells 1 week later and the survival of mice were monitored. All mice vaccinated with p‐c treated cells (□) appeared to be protected and survival was significantly prolonged, whereas the mice implanted with naive CT26 cells (▴) died soon. (B) Depletion of the immune cell subsets in vivo. CD4⁺, CD8⁺ or NK cells were depleted by intraperitoneal injection of 500 μg anti‐CD4⁺ (clone GK 1.5, rat IgG), anti‐CD8⁺ (clone2.43, rat IgG) or anti‐NK (clone PK136) mAb, respectively, 4 days before challenge with p‐c treated dying CT26 tumour cells and 3 days before injection of live CT26 cells. Depletion of CD8⁺ T lymphocytes showed complete abrogation of the antitumour activity, whereas the depletion of CD4⁺ T lymphocytes showed partial abrogation. Data represent day 25 after naive tumour cell injection. Similar results can be found at other time‐points. Asterisks (*) indicate a significant difference in tumour volume (P < 0.05) between CD4⁺‐depleted and other groups.