Fig. 2.

Differential effects of human IgG and IgG-F(ab′)₂ fragments on the induction of apoptosis of SEB-stimulated monocytes by abatacept. Highly purified monocytes (1 × 10⁶/well) from healthy individuals were cultured in the presence of SEB (100 pg/ml) in each well of 24-well flat-bottomed microtiter plates with abatacept (100 μg/ml) for 48 h, with or without IgG (100 μg/ml), or with IgG-F(ab′)₂ fragments (100 μg/ml). After the cultures, the cells were stained with PE-conjugated annexin V, followed by analysis on flow cytometry. Percentages of total annexin V-positive cells (upper, n = 3) or PI-negative annexin V-positive cells (lower, n = 3) are shown. Error bars indicate SD values of three different experiments. Statistical significance was evaluated by Wilcoxon’s signed-rank test. V-positive cells (a) and PI-negative annexin V-positive cells (b)