The protein kinase Cβ (PKCβ)–specific inhibitor enzastaurin induces apoptosis of lupus B cells and prevents lupus development in Sle mice. A, Effect of enzastaurin on apoptosis of lupus B cells. Purified splenic B cells were treated with anti-IgM antibody in the presence or absence (control) of enzastaurin for 48 hours and analyzed with an annexin V detection kit. The fractions of annexin V–positive (apoptotic) cells in the samples treated with only anti-IgM (control) are set at 1. B, Sensitivity of human 9G4-positive and 9G4-negative B cells to PKCβ inhibition. Purified splenic B cells were treated with enzastaurin for 24 hours. The apoptotic fractions from untreated samples are set at 1. Results are representative of 2 independent experiments. C, Levels of serum IgG anti–double-stranded DNA (anti-dsDNA) and antihistone/anti-dsDNA autoantibodies from vehicle-treated control mice and enzastaurin-treated mice, as analyzed by enzyme-linked immunosorbent assay. Bars in A–C show the mean ± SD of 3 independent experiments. D, Representative immunofluorescent images of IgG deposition (top) and glomeruli (bottom) in kidney sections from Sle1.Sle3 mice treated with vehicle or enzastaurin. Original magnification × 20 (top); × 40 (bottom). PAS = periodic acid–Schiff.