Immunologic Deficiencies in Senescence: II. Characterization of Extrinsic Deficiencies¹

The purpose of this investigation was to characterize immunologic deficiencies which occur in senescent mice. Extrinsic deficiencies, i.e., environmental deficiencies, were studied by transfer of immunocompetent cells into either young or old mice and assessment of the capacity of the cells to generate IgM antibody-forming cells. Non-cellular (environmental) factor(s) in the old mice were observed to be detrimental to the rate of growth of the antibody-forming cell population and to the full expression of the immune potential of normal young immunocompetent cells.