ApoE enhances NKT- and B-cell activation by α-galactosylceramide. NKT cells and tonsil B cells were cultured in SFM plus αGalCer (0-500 ng/mL) with (top row) or without (bottom row) apoE (2.5 μg/mL) as indicated. On day 4 of culture, cells were counted and stained with anti-CD19, anti-CD3, and anti–Ki-67. (A) Representative dot plots of CD19 and intracellular Ki-67 expression on day 4 of culture. Average (mean ± SEM) total B-cell number (B), Ki-67^hi B-cell number (C), total NKT-cell number (D), and Ki-67^hi NKT-cell number (E) obtained from 5 individual tonsils from independent experiments. Significant differences (paired t test): *P < .05; **P < .001.