Figure 6.

Expression of mSLAM on normal and mSLAM transfected L cells, and the effects of mSLAM transfectants and sSLAM cross-linked to polystyrene latex beads on B cell proliferation. Normal L cells (A) and L cells transfected with cDNA encoding mSLAM (B) were stained with PE-conjugated SLAM-specific mAb A12 (stippled histograms) or a PE-conjugated, isotype-matched control Ab with irrelevant specificity (open histograms), and the cells were analyzed by flow cytometry. (C ) Negatively selected B cells were cocultured in the presence or absence of irradiated (7,300 rad) normal or SLAM transfected L cells (L-SLAM), anti-CD40 mAbs (10 μg/ml), IL-4 (100 U/ml), and/or IL-10 (100 U/ml) as indicated. Data represent mean ± SD of triplicate cultures in three separate experiments. (D) Polystyrene latex beads coated with sSLAM by using anti-Flag mAb M2 (SLAM-beads) were cocultured with purified B cells under culture conditions indicated. Polystyrene latex beads coated with only anti-Flag mAb (αFlag-beads) were used as controls. Proliferation was measured by [³H]thymidine incorporation during the last 16 h of a 4-d culture. Data represent mean ± SD of triplicate cultures.