Fig. 3. Induction of CD21 shedding by thiol antioxidants. 293-CD21 cells (A), Daudi B cells (2x10⁶ cells/ml) (B) and PBMC from four healthy donors (5x10⁶ cells/ml) (C) were stimulated for 4 hours with 5 mM reduced glutathione (GSH), 5 mM oxidized glutathione (GSSG), 5 mM NAC, 1 mM or 2.8 mM ß-mercaptoethanol (2-ME). Cell culture supernatants were collected and sCD21 was measured by ELISA; values expressed as pg sCD21/ml/median fluorescence intensity of respective cells. Data are means of three independent experiments each measured in triplicate.