CONDITIONS PERMITTING SHORT-TERM ENGRAFTMENT OF HUMAN T-CELLS IN RAG-1 MUTANT MICE

The ability to reconstitute RAG-1 deficient (R-) mice with human perip heral blood cells was examined using four different host preparative r egimens. Our results indicate that while untreated R-mice could be rec onstituted with human cells, pre-conditioning with either 5Gy whole bo dy irradiation (WBI) or anti-asialo GM1 rabbit anti-serum led to an in crease in the frequency of CD45(+) human cells that could be detected in the circulation. Pre-conditioning with both anti-asialo GM1; and WB I led to a further increase in the frequency of circulating human cell s in reconstituted R- mice. Human CD45(+) cells were detected in the s pleen and lymph nodes, but not the thymus of reconstituted mice pre-co nditioned with WBI and anti-asialo GM1. Our results suggest that mouse NK cells and a limitation in physical space are limiting factors medi ating resistance to human cell engraftment in R- mice.