Characterization of the levels of various immune cells in the tumor microenvironment following treatment with imiquimod. C57BL/6 mice were divided into two groups (5/group: vehicle treated or imiquimod treated) and were implanted with TC-1 (5 × 104/mouse) at d0. Each mouse received topical vehicle cream or imiquimod (50 mg/mouse) every two days initiated at d6 for a total of 6 times. Tumors were harvested 6 hours after last imiquimod treatment. Tumor cells were then made into single cell suspension, washed once in FACScan buffer, and stained with surface markers for various innate and adaptive effectors including PE-conjugated anti-CD4 (L3T4), PE-conjugated anti-CD8 (53-6.7), FITC-conjugated anti-GR-1 (RB6-8C5), PE-conjugated anti-CD19 (1D3), PE-conjugated anti-NK1.1 (PK136), and PE-Cy5-conjugated anti-F4/80 (BM8). Cells were subjected to flow cytometric analysis gated on lymphocyte population (*, p < 0.05, imiquimod versus vehicle). Representative data from one of three independent experiments are shown.