Inhibition of Syk prevents murine antibody-mediated cytopenias. (A) CD1 mice were pretreated with nothing (Nil), vehicle, R788 (at the dose indicated), or IVIg on day 1. Mice in the vehicle and R788 groups were injected again (8 hours apart) on day 2. All mice except for the unmanipulated group were injected with antiplatelet antibody on day 2. Mice were bled on day 3 for platelet counting as detailed in “Methods.” n = 6 mice per group. (B) Mice were treated as in panel A, except that anemia was induced by injection of antierythrocyte (TER119) antibody. All data are expressed as mean plus or minus SEM (n = 6 mice per group).