Normal B-cell proliferation in B7-H2^–/– mice. Splenic B cells isolated from wild-type (▪) and B7-H2^–/– (□) mice were stimulated in vitro with varying concentrations of anti-IgM (left panel), anti-CD40 (middle panel), or LPS (right panel). Proliferation was assessed by [³H]thymidine incorporation after 64 hours. The results represent the average of triplicate wells, and the error bars depict the SDs. Data shown are representative of 2 independent experiments performed.