Effect of anti-A2 on IgG-APS–induced expression of ICAM-1 and E-sel in HUVECs. HUVECs were cultured and treated with either 200 μg/mL IgG-APS or 200 μg/mL IgG-NHS in the presence or absence of 1 μg/mL anti-A2 IgG Ab or 1 μg/mL MuMoAbC, as indicated in “In vitro detection of surface E-sel and ICAM-1 on EC.” Some cells were treated with LPS, as a positive control, or with medium alone, as a negative control. ICAM-1 (A) and E-sel (B) expression were determined by cyto-ELISA, and the data expressed as means ± SD in O.D. units. Experiments were run in triplicate and performed 3 times. ¶Statistically different from medium-treated cells (P = .001). *Statistically different from IgG-NHS–treated cells (P = .001). **Statistically different from IgG-APS–treated cells (ICAM-1, P = .001; E-sel, P = .001).