Figure 2.

Proliferation of purified B cells in response to various stimuli. (A) Purified splenic B cells from wild-type (•) or SHIP^−/− (♦) mice were incubated with intact goat anti–mouse IgM antibody in the presence (solid line) or absence (broken line) of the anti-FcR antibody 2.4G2 for 60 h before addition of [³H]thymidine for determination of specific incorporation. Results are the mean ± SEM of triplicate determinations (four experiments with cells pooled from three or four mice per experiment). Purified splenic B cells from wild-type (•, solid line) and SHIP^−/− (♦, broken line) mice were incubated with various concentrations of the F(ab′)₂ fragment of goat anti–mouse IgM antibody (B) or bacterial LPS (C), and proliferation was determined as above. (D) Purified splenic B cells from wild-type (white bars) and SHIP^−/− (black bars) mice were incubated with the indicated concentrations of IL-4 or anti-CD40 culture supernatants. (E) Wild-type (•, solid line) and SHIP^−/− (♦, broken line) B cells were incubated with 1% IL-4 supernatant and the indicated percentages of anti-CD40 supernatant for determination of proliferation as indicated above. Statistical analysis between similarly treated wild-type and SHIP^−/− cells was carried out using the Student's t test. *P ≤ 0.05; **P ≤ 0.005.