Fig. 2. Pervanadate induced CD21 shedding in Daudi B cells, PBMC and 293-CD21 cells. 2x10⁶ Daudi B cells/ml (A), 3.4x10⁶ PBMC/ml isolated from four healthy donors (B) and 293-CD21 cells (C) were incubated for 4 hours with increasing concentrations of pervanadate. (A,C) Cell culture supernatants from 293-CD21 and Daudi B cells were collected and the amount of sCD21 was determined by ELISA. Data for 293-CD21 cells are means of three independent experiments, data for Daudi B cells are means of four independent experiments, each measured in triplicate (pg sCD21/ml/median fluorescence intensity of respective cells. (B) PBMC from four healthy donors were collected and cell surface CD21 of primary B cells was measured by flow cytometry after staining with anti-CD21-RPE. n.d.: not determined.