Effect of splenectomy on establishment of hematopoietic chimerism in nonirradiated mice.

When spleen cells (1.5 x 10(8)) from beige C57BL/6 (bgJ/bgJ, Chediak-Higashi syndrome) mice were injected into nonirradiated (C57BL/6 x CBA)F1 hybrid mice, the hematopoietic stem cells of the hybrid host were eradicated by graft-versus-host (GVH) reaction, and peripheral neutrophils of the host changed from normal type to beige type with giant sudanophilic granules in 20 days after the cell injection. Effect of splenectomy on the establishment of such hematopoietic chimerism was investigated. The splenectomy carried out either before or after the cell injection reduced the proportion of mice in which more than 90% of peripheral neutrophils became of beige type. Since the mortality of mice which received splenectomy at various days prior to or after the cell injection paralleled the proportion of establishment of chimerism, the splenectomy does not seem to affect directly the establishment of chimerism but indirectly through the modification of the intensity of GVH reaction.