Requirement for lymphocytes and iDCs. A, combining G47Δ infection of subcutaneous N18 tumors with intratumoral iDC injection does not slow progression relative to treatment with G47Δ alone in immunodeficient NOD-SCID mice. B, combining G47Δ injection of subcutaneous N18 tumors with intratumoral injection of mature dendritic cells does not slow progression relative to treatment with G47Δ alone in syngeneic A/J mice (G47Δ/mature dendritic cells versus G47Δ, P = 0.8; G47Δ versus G47Δ/iDC, P = 0.02; G47Δ/iDC versus G47Δ/mature dendritic cells, P = 0.15, Student’s t test). Enhanced antitumor effect is dependent on use of iDCs.