Figure 3

Activated MC respond to C5a in vivo. Precursor cell-derived murine MC cultured with IL-3 and SCF were treated or not (Ø) with ionomycin, PMA or Ag (DNP-albumin, following a 24 h preincubation period with IgE anti-DNP) for different periods as indicated. Subsequently, MC were labeled with PKH26. In (C, D), labeled MC were additionally preincubated at 37°C without (Ø) or with C5a (2 μg) to induce receptor desensitization. In (E), labeled MC were preincubated on ice without (Ø) or with mAb 1240 (20 μg, rat IgG1) to block C5aR, or with mAb 1G4 (20 μg, rat IgG1), as a control. Thereafter, labeled MC were injected i.v. into syngeneic BALB/c mice together with C5a (10 μg) i.p.. After 4 h (A, B, E) or 24 h (C, D, F), peritoneal cells were harvested and labeled migratory cells identified by FACS analysis. Mean values (± SEM) of 3 (A, B, D) or 4 (C, E, F) independent experiments each are shown.