Deficient cross-presentation of soluble ovalbumin by neonatal DCs. Neonatal (▪) and adult (▦) DCs (1 × 104 cells) were incubated with soluble ovalbumin (50 μg/mL) or the MHC class I-restricted ovalbumin peptide SIINFEKL (10 μM) along with nothing (REST), LPS (100 ng/mL), or pI:C (50 μg/mL) for 18 hours. After 3 washes, purified adult OT1 CD8+ T cells (1 × 105 cells) were added, and after 48 hours cultures were pulsed with 5 μCi (0.185 MBq) 3H-thymidine for 18 hours. Background proliferation of DCs alone, T cells alone, or DCs plus T cells but without ovalbumin or peptide was always less than 1000 counts per minute (cpm). Error bars indicate the standard error of the mean (SEM) of triplicate samples for this experiment. The graphs show one representative experiment of 3.
