Fig. 3.

CD4⁺ T cells primed with irradiated CD133⁺ tumor cell/dendritic cell (DC) vaccine mediated potent and long-lasting antitumor reactivity. Both CD4⁺ and CD8⁺ T cells were required for optimal antitumor efficacy. a Approximately 15 × 10⁶ CD62L^low T cells isolated from lymph nodes (LNs) draining irradiated CD133⁺ melanoma cells/DCs for 8 days were cultured by the anti-CD3/interleukin (IL)-2 method and were infused intravenously into mice bearing 2-day-established skin tumors of parental melanoma. Mice were intraperitoneally injected with either anti-CD4 or anti-CD8 monoclonal antibody (mAb). The diameter of the skin tumors was measured twice weekly with calipers; size was recorded as the average of 2 perpendicular diameters. Each group contained 5 mice. Asterisks indicate P < 0.01. b CD4⁺ and CD8⁺ T cells were purified from CD62L^low LN T cells draining irradiated CD133⁺ melanoma cells/DCs with immuno-magnetic beads. Approximately 3 × 10⁷ CD62L^low T cells, 1 × 10⁷ CD62L^low CD8⁺ T cells, or 1 × 10⁷ CD62L^low CD4⁺ T cells were isolated from 8-day B16 CD133⁺ tumor cell/DC-draining LN cells. CD62L^low T cells were activated by the anti-CD3/IL-2 method and separated into CD4⁺ and CD8⁺ cells with magnetic beads. The diameters of the skin tumors were measured twice weekly with calipers; size was recorded as the average of 2 perpendicular diameters. Each group contained 5 mice. Asterisks indicate P < 0.01