Abstract
Generation of natural killer (NK) cells in spleens from radiation chimeras produced between pairs of histocompatible 'high' and 'low' NK-reactive mouse strains has been investigated. Spleen cells of high-reactive recipients reconstituted with bone marrow from low-reactive mice were found to be low reactive. Conversely, spleen cells of low mice grafted with bone marrow or fetal liver cells from high donors were high reactive. Similarly, the age-related changes of NK activity were shown to be expressed at the bone marrow precursor cell level. These results indicate that the generation of natural killer cells is an inborn and autonomous function of the bone marrow and does not depend on the genotype or other influences of the host environment.