Figure 4.

Intratumoral injection of adenovirus encoding MART-1 cDNA transduced dendritic cells (AdVMART-1/DCs) before, but not after, radiation therapy prevents radiation-induced immune suppression. C57BL/6 mice bearing 5–6-mm-diameter B16 tumours were irradiated (0 or 10 Gy) 1 day before or after the intratumoral delivery of AdVMART-1/DCs (5 × 10⁵). Six groups of mice were used in this study: (i) without tumours or treatments; (ii) with tumours and no treatments; (iii) with B16 tumours irradiated with 10 Gy; (iv) with tumours injected with AdVMART-1/DCs; (v) with tumours and AdVMART-1/DCs injected 1 day prior to local tumour irradiation (10 Gy); and (vi) with tumours irradiated (10 Gy) followed 1 day later by AdVMART-1/DC injection. One week after the first treatment, interferon-γ (IFN-γ)-producing lymphocytes were detected using enzyme-linked immunospot (ELISPOT) assays after 48 hr of restimulation with EL4(MART-1) cells (black bars) or EL4 cells (white bars), or with no restimulation (control; grey bars). Three mice were used in each treatment group. The results shown are the mean ± 1 standard error of the mean (SEM) of triplicate data from one representative experiment of two carried out (*P< 0·05 as compared with the EL4(MART-1)-restimulated group).