Dendritic cells from A20 lymphoma-bearing mice have impaired antigen-presenting capabilities. BALB/c mice were injected intravenously with 1 × 10⁶ A20 WT lymphoma cells. Three weeks later, animals were killed and CD11c⁺ splenic DCs were isolated by magnetic sorting. Purified anti-HA T cells (2 × 10⁶) were then plated for 10 hours with 2 × 10⁵ DCs from lymphoma-bearing (right) or control tumor-free (left) mice in the presence or absence of cognate peptide. Each dot plot is gated on the CD4⁺/6.5⁺ clonotypic population and shows the percentage of anti-HA T cells positive for IL-2 or IFN-γ, as determined by intracellular cytokine staining. DCs were obtained from 4 mice, and the experiment was repeated twice with similar results.