Engraftment following T-cell-depleted bone marrow transplantation: II. Stability of mixed chimerism in semiallogeneic recipients after total-body irradiation

Chronic, stable mixed chimerism of both lymphocytes and erythrocytes was observed in semiallogeneic murine recipients of T-cell-depleted bone marrow transplants that had been conditioned with supralethal total-body irradiation (1100 cGy). Mixed chimerism was extensive, with a wide range of donor engraftment persisting for at least one year after transplant. In both erythrocyte and lymphocyte lineages, decreasing donor engraftment correlated with decreasing marrow dose; however, complete red cell engraftment was more easily achieved than complete lymphocyte engraftment. There were no late graft failures, even among animals exhibiting a substantial host component of hematopoiesis. The extent of mixed hematopoietic chimerism therefore appears to be much greater than had been expected in recipients of T-cell-depleted bone marrow transplants.