Secondary disease mortality in rat-mouse radiation chimeras

Two statistical experimental designs were used to investigate factors involved in 90-day mortality from secondary disease in lethally irradiated mice treated with rat bone marrow. Secondary disease is a graft-versus-host syndrome that has a mortality of about 65-95% in this transplant situation. When the factors--age-of-donor-cells, day-of-cell-injection, dose-of-marrow-cells, sex, and environment--were examined for their main effects and interactions, some combinations of these factors were found to give about 25% 90-day mortality. The experiments indicate that the lowest mortality can be achieved with an injection of 40 million or more cells 1 day after irradiation and an ultraclean environment of unlimited filter-top caging.