Tumor cells that express ULBPs are rejected in syngeneic mice. C57BL/6 mice were challenged subcutaneously with 3 × 105 EL4 (A) or RMA (B) tumor cells expressing ULBP1 (•), ULBP2 (▴), ULBP3 (○), RAE-1β (□), or vector alone (▪). Tumor sizes were measured and mean tumor size (± SEM) was calculated from all surviving mice in each group. (A) Ten of 10 mice that received EL4 mock cells developed tumors and were humanely killed on day 18 due to tumor burden; none of the mice (n = 10/group) that received ULBP1-, ULBP2-, or ULBP3-expressing EL4 cells grew tumors; 3 of 10 mice that received RAE-1β–expressing EL4 cells developed tumors, and one was humanely killed at day 26 due to tumor burden. (B) Six of 6 mice that received RMA mock cells developed tumors and were humanely killed on day 14; 7 of 9, 5 of 7, 6 of 8, and 1 of 8 mice that received ULBP1-, ULBP2-, ULBP3-, or RAE-1β–expressing RMA cells, respectively, grew tumors. Data are representative of 4 independent experiments.
