Stable chimerism induced in noninbred rabbits by neonatal injection of spleen cells from allotype-suppressed adult donors. I. Replacement of hemopoietic tissue by donor cells.

In the course of experiments designed to demonstrate an active mechanism of allotype suppression in rabbits, spleen cells from adult donors were transferred to newborn recipients. Among 23 rabbits that received injections, 4 stable chimeras were formed, as determined by the production of serum immunoglobulins marked with light and heavy chain allotypes. The other rabbits that survived the immediate postinjection period displayed a temporary chimeric state lasting up to several weeks, after which they either succumbed to graft-versus-host disease or rejected the donor cells. One chimeric animal was apparently repopulated by the hemopoietic cells of the donor's spleen. Insofar as could be determined, the recipient's blood cells became phenotypically identical to those of the donor. This condition manifested itself as a loss of the recipient gene products associated with both lymphocyte and erythrocytes, accompanied by a seemingly total replacement with those of the donor.