Studies on the distribution of macrophages derived from rat bone marrow cells in xenogeneic radiation chimaeras.

Lethally-irradiated mice were injected with rat bone marrow cells and examined subsequently for the presence of rat macrophages, using an indirect fluorescent antibody test in conjunction with a fluorochrome-labelled phagocytic cell marker. Donor bone marrow cells were fractionated by (1) adherence, (2) magnetic removal of phagocytic cells containing ingested carbonyl iron and (3) treatment with lymphocyte-absorbed anti-rat macrophage serum either or . Extensive rat cell proliferation occurred in the resulting xenogeneic chimaeras by or after Day 4 and increased during the next week. The precursor of both the free and fixed macrophages was contained in the non-adherent, non-phagocytic population of bone marrow cells. The anti-macrophage serum was not selective and abolished the capability of bone marrow cells to proliferate.