Fig. 5

CTLA-4-Ig has no effect on T cell-dependent stimulation- or SAC-induced plasma cell differentiation or antibody secretion. Purified B cells were stimulated with anti-IgM (5 μg/ml), anti-CD40 (1 μg/ml) antibody, and IL-21 (100 ng/ml), or with SAC in the presence of Ctrl-Ig or CTLA-4-Ig for 4 days, and the cells (a and c) were stained with anti-CD27 and anti-CD38 antibodies to mark plasma cells (CD38^highCD27^high; n = 3). One representative result is shown. b ELISPOT assay results after TD stimulation. Two thousand B cells (activated for 4 days) were seeded on a 96 well plate precoated with anti-hIgG antibody in triplicate, and the cells were incubated 16 h at 37 °C in complete RPMI medium. After removing the cells, anti-hIgG antibody conjugated with biotin was added to mark antibody secreting cells (ASC). The mean spot number was quantified by an AID ELISPOT reader and analyzed by AID ELISPOT software. Upper, one representative result. Lower, cumulative ELISPOT assay results of samples from 3 donors. d IgM secretion after SAC stimulation for 3 days. IgM in the supernatant of the activated B cells was measured using ELISA