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 peripheral blood cells was examined using four different host preparative regimens. Our results indicate that while untreated R ‐ mice could be reconstituted with human cells, pre‐conditioning with either 5Gy whole body irradiation (WBI) or anti‐asialo GM1 rabbit anti‐serum led to an increase in the frequency of CD45 + human cells that could be detected in the circulation. Pre‐conditioning with both anti‐asialo GM1 and WBI led to a further increase in the frequency of circulating human cells in reconstituted R ‐ mice. Human CD45 + cells were detected in the spleen and lymph nodes, but not the thymus of reconstituted mice pre‐conditioned with WBI and anti‐asialo GM1. Our results suggest that mouse NK cells and a limitation in physical space are limiting factors mediating resistance I to human cell engraftment in R ‐ mice.