Figure 3.

SMG exposure reverses E.G7 tumor-mediated suppression of CD4⁺ T cell activation. E.G7 tumor cells (2 × 10⁵/ml) were cultured in Static (gray bar) or SMG (black bar) conditions for 72 h. (a) Following culture, Static and SMG E.G7 were collected and enumerated by Trypan exclusion for the total number of cells in the 10 ml cultures. (b) Additionally, the Static and SMG E.G7 cancer cells were stained with 7-AAD and analyzed by flow cytometry for the numbers of 7-AAD⁺ (apoptotic) cells within the Static and SMG E.G7 population (×100%). For each bar, the data represent the mean + SD of three independent, paired cultures. (c) Following culture, Static and SMG E.G7 cells were harvested, washed and incubated (2.5 × 10⁴) separately with JAWS II DC (5 × 10⁴) for 8 h. To each co-culture, CD4⁺ OT-II TCH (1.25 × 10⁵) and OVA323 (0.1 mg/ml) were added and incubation continued for 24 h. Control wells were included that contained DC, OT-II TCH and OVA323 antigen (white bar). IL-2 was assessed by ELISA from culture supernatants. For each bar, the data represent the mean + SD of n = 6 of two independent experiments (n = 12/condition). **p-value ≤ 0.001 comparing OT-II TCH IL-2 production when DC exposed to Static and SMG cultured E.G7 tumor cells.