Figure 4

Infiltration of immune cells into the large established immunosuppressive LLC tumors is improved after combination therapy. C57BL/6 mice (n = 4 per group) were challenged subcutaneously on the right hind limb with 5 × 10⁵ 3LL-GFP cells. 18 days after tumor challenge mice were treated with local radiation alone (36 Gy total, divided into 3 equal fractions on 3 consecutive days) (RTX alone), vaccination alone (32 μg, twice a week, started at day 18) (RNA alone) or with radioimmunotherapy (with first vaccination given on day 19) (RNA + RTX). Untreated mice served as a control (No therapy). On day 25 tumors were excised, homogenized and immune cell infiltration analyzed by flow cytometry. (A) MHC class I expression was analyzed on single cell suspension of untreated- and irradiated tumor cells. (B) CD45.2⁺ host-derived immune cells were characterized by cell surface staining of several lineage markers and the ratio of different CD45.2⁺ immune cell subpopulations to CD45.2^- tumor cells is shown as median of four animals per group. * p < 0.05. Presented data show representative results of two independent analyses.