DC activation by protein/H complexes. Murine DCs were isolated from nonimmunized C57Bl/6 mice and incubated with PRT + H, Lys + H, mPF4 + H, buffer containing media (Buffer), H (0.4 U/mL) or lipopolysaccharide. IL-12 was measured from cell supernatants by ELISA. Shaded bars indicate protein/H complexes and light shade is uncomplexed protein. One-tailed paired t test was used for determining significance. *P < .01 for PF4 vs PF4/H; **P < .001 for PRT vs PRT/H; P = ns for Lys vs Lys/H.