Prophylactic activity of tumor-specific CTL clone is enhanced by IL-10 in MC38 models.

(A) An MC38-reactive CTL clone expressing CD25⁺, CD69⁺, CD122⁺, and CD44^hi phenotype and capable of secreting IFN-γ, but not IL-2 and IL-4, in a stable state was used in adoptive-protection experiments. (B) Injection of the MC38-reactive CTL clone, followed by IL-10, suppressed the growth of subsequently transplanted MC38 tumors. As in the schedule of the experiment in Figure 2, 1 × 10⁵ cells of the CTL clone were adoptively transferred into syngeneic B6 mice. One week later, 3 × 10⁵ MC38 were inoculated as a tumor challenge. Scheduling IL-10 injections (40 μg per mouse for 7 consecutive days) was different in each treatment group and was allowed for the discrimination of IL-10 effects when provided before CTL transfer (IL–10-CTL–MC38) versus after CTL transfer (CTL–IL-10–MC38) or after tumor challenge (CTL–MC38–IL-10).