Figure 2.

Peracetylated sialic acid enhances GD2 expression. A, structural representation of Neu5Ac (left) and the peracetylated form Ac₅Neu5Ac (right). B, effect of sialic acid supplementation on GD2 expression of IMR-32 cells. The cells were cultured for 3 days with 0–5 mm Neu5Ac or Ac₅Neu5Ac, and GD2 expression was assessed by flow cytometry. The bar diagram shows the mean percentage of GD2 expression ± S.E. of IMR-32 cells treated with Neu5Ac or Ac₅Neu5Ac normalized to control (n = 3). C and D, IMR-32 and SK-N-AS cells were cultured for 3 days with 0–512 μm Ac₅Neu5Ac and stained with anti-GD2 antibody. Bar diagrams show GD2 expression of IMR-32 cells (C) and SK-N-AS cells (D) as mean fluorescence intensity ± S.E. of three independent experiments. E and F, effect of Ac₅Neu5Ac on cell viability. Bar diagrams show mean percentage of viable IMR-32 cells (E) and SK-N-AS cells (F) ± S.E. in culture after treatment with 0–512 μm Ac₅Neu5Ac for 3 days (n = 3).