BCR-dependent activation did not inhibit HLA class I expression. Naive B cells were cultured on irradiated CD32-L cells in the presence of 1 μg/mL anti-CD40 MoAb alone, 5 μg/mL anti-BCR MoAb alone, or the combination of both. After 5 days cells were collected and stained with FITC-conjugated anti-CD56, anti-CD20, anti-Fas UB2, or MoAb90 followed by staining with FITC-conjugated antimouse antibodies. Filled histograms represent staining with a negative control MoAb. This figure is representative of three independent experiments.