Only progressor-adherent splenocytes suppress anti-CD3–stimulated IFN-γ production by CD8⁺cells. Splenocytes (SPCs) from mice that almost fully rejected their tumor (regressors) were stimulated for 6 hours with anti-CD3 (with Golgi blockade during the last 4 hours), either alone (control), in the presence of 30% purified splenic CD11b⁺Gr-1⁺ cells from naive AKR or late progressors, or in the presence of 30% 5-day adherent splenocytes (adh SPC) from naive AKR or late progressors. Subsequently, cells were stained with FITC-labeled anti-CD8, fixed, permeabilized, and stained intracellularly with PE-labeled anti–IFN-γ or isotype control. For each condition, the percentage of IFN-γ⁺ cells within the gated CD8⁺ population was calculated. Bars represent the percentage increase or decrease in the number of IFN-γ⁺CD8⁺ cells relative to control regressor splenocytes. Bars are averages ± SD from 2 experiments. Note that hardly any IFN-γ production could be seen in any condition without anti-CD3 stimulation.