A search for lymphocyte-derived macrophages during xenogeneic graft-verus-host reactions induced by rat thoracic duct cells.

Lethally-irradiated mice were injected with rat thoracic duct lymphocytes and examined for the presence of macrophages of donor genotype as an indication of lymphocyte to macrophage transformation. Donor cell proliferation was identified by karyotypic analysis and by an indirect fluorescent antibody technique capable of detecting rat cells in a mouse host. Macrophages were characterized in the former procedure by association of Berlin blue particles with mitotic figures and in the latter by phagocytosis of fluorochrome-conjugated bacteria. In spite of reticuloendothelial stimulation provided by the xenogeneic graft--host reaction, no significant evidence was obtained for the presence of a functional macrophage of rat lymphocyte derivation using a variety of donor/recipient strain combinations and dosage parameters. In contrast, irradiated mice inoculated with rat bone marrow cells contained large numbers of donor-derived fixed and free macrophages.