Release of mast cell mediators in the peritoneal cavity affects bone marrow mast cell numbers . (A) Mast cell depletion of the peritoneal cavity by distilled water results in an immediate reduction in the percentage of mast cells in the bone marrow. (B) Two days after i.p. injection of Compound 48/80 the percentage of mast cells in the bone marrow is reduced in a dose dependent manner. (C) Two days after i.p injection of anti-IgE in concentrations above 2.5 μg/animal, but not IgG the percentage of mast cells in the bone marrow is decreased. Mast cells were isolated from the bone marrow using magnetic beads conjugated to mAb BGD6. The number of cells free or attached to the magnetic beads was determined by counting the cells in a hemocytometer. The average of 3 independent experiments ± SD is shown.