Reconstitution of the T-cell compartment after bone marrow transplantation depends on
successful colonization of the thymus by bone-marrow-derived progenitor cells. Recent studies
compared the development of syngeneic and allogeneic bone-marrow-derived cells in cocultures
with lymphoid-depleted fetal thymus explants, leading to the discovery of MHC-linked
syngeneic developmental preference (SDP) in the thymus. To determine the nature of cell
interactions among the bone marrow and thymic elements that might underlie SDP, we analyzed
this phenomenon by mathematical modeling. The results indicate that syngeneic mature T cells,
responsible for inducing this preference, probably interfere both with the seeding of allogeneic
bone-marrow-derived thymocyte progenitors in the thymic stroma and with their subsequent
proliferation. In addition, the possibility of augmented death among the developing allogeneic
thymocytes cannot be ruled out