Allograft enrichment with naive donor Tregs promotes macroengraftment beyond the threshold of immunocompetence. The frequency of macroengraftment is plotted against the frequency of CD4⁺CD8⁻ cells among CD3⁺ T cells in the PB of uninjected littermates with the previously determined threshold of immunocompetence (≥10%) delineated by the dashed line.