Specific SYK inhibition prevents splenomegaly in a mouse model of chronic BCR stimulation. (A) mouse splenocytes were isolated and treated with various concentrations of P505-15 as shown. Data represent inhibition of anti-IgD mediated B-cell activation (CD80/86 MFI) relative to vehicle control (mean + S.D., n = 4). (B) mice were injected subcutaneously with goat serum (GS) or anti-IgD. Average spleen weight is graphed (mean + S.D., n = 5) from mice treated as indicated. *Statistical difference (P < 0.05) relative to anti-IgD mice treated with vehicle control (Vh). The subset photograph depicts two representative spleens from each group of mice treated with GS and vehicle control (left set), anti-IgD with vehicle (middle set), and anti-IgD with 15 mg/kg P505-15 (right set). (C) representative H&E staining of spleen sections from mice treated with GS (left panel), anti-IgD with vehicle (middle panel), and anti-IgD with 15 mg/kg P505-15 (right panel).