DONOR-DERIVED PLASMA TRANSFERRIN FACILITATES THE ENGRAFTMENT OF XENOGENEIC (RAT) BONE-MARROW IN IRRADIATED MICE

Endogenous factors originally found in the bone marrow (BM) and facili tating the engraftment of xenogeneic (rat) BM in lethally irradiated m ice have been recently identified as transferrins (Tf). Tf have been s eparated and purified from plasma pools of inbred Rii/2 rats and injec ted in lethally irradiated BALB/c and C57BL/6 mice 1 h before the infu sion of BM and for several days after BM transplantation. Other groups of irradiated mice have been similarly treated with human Tf, Tf from other strains of rats different from the BM donors and with human or rat serum albumin. A remarkable facilitation of BM engraftment and a d urable graft-versus-host disease (GVHD)-free hemopoietic chimerism hav e been achieved in the irradiated mice when a combination of BM and Tf from the same donor rat (Rii/2) strain was used for transplantation. Durable survival and persistent chimerism were not observed in the con trol groups. It seems that donor Tf profoundly affects the outcome of BM transplantation when combined with donor BM. These results indicate that the mechanism by which Tf promotes engraftment of xenogeneic BM deserves investigation in order to improve this novel procedure and to extend it to other species and possibly to man.