Bone marrow origin of mast cell precursors in mesenteric lymph nodes of mice.

Concentration of mast-cell precursors in the mesenteric lymph node of (WB X C57BL/6)F1 hybrid mice (WBB6F1) were evaluated by a limiting dilution method. Cells from WBB6F1-+/+ mice were injected directly into the skin of WBB6F1-W/Wv mice which genetically lack tissue mast cells. Concentrations of mast-cell precursors were calculated from the proportion of injection sites at which mast cells appeared. Although immunization with horse serum significantly increased the concentration of mast-cell precursors in the mesenteric lymph node, the concentration in the lymph node remained about 10% that observed in the peripheral blood mononuclear cells. Since the bone marrow origin of mast-cell precursors in the mesenteric lymph node was demonstrated by using giant granules of beige (C57BL/6-bgj/bgj) mice as a marker, the immunization seemed to increase the migration of bone-marrow-derived mast-cell precursors from the peripheral blood to lymph node.