Adoptive transfer of spleen cells from mice treated with radioactive strontium: suppressor cells, natural killer cells, and "hybrid resistance" in recipient mice.

Abstract

Abstract B6D2F1 mice were treated with the bone-seeking isotope, 89Sr, to deplete marrow-dependent (M) cells. Spleen cells from these mice or age- and sex-control mice were infused into lethally irradiated syngeneic recipients. At various intervals after cell transfer, the animals were assessed for a variety of immune functions, some of which were known to be abnormal in mice treated with 89Sr. Suppressor cells capable of inhibiting antibody responses in vitro were detected in most recipients of spleen cells from 89Sr-treated mice. These suppressor cells had properties similar to those of the donor mice (radiosensitive, adherent to Sephadex G-10 columns). Spleen cells of 89Sr-treated mice filtered over G-10 columns lost suppressor cell function in vitro but were able to adoptively transfer the suppressor cell function. Natural killer (NK) cell function was decreased in the majority of recipients of experimental spleen cells. As in the donor mice treated with 89Sr, no evidence for suppressor cells capable of inhibiting natural killer cell function at the effector cell stage was obtained. There was no direct association between low NK cell function and high suppressor cell function in these spleen cell radiation chimeras. The ability of B6D2F1 spleen cells to generate anti-B6 cytolytic T cells in vitro (F1 anti-parent) was decreased in 89Sr-treated mice as well as in recipients of spleen cells from 89Sr-treated donor mice in most instances. However, B6D2F1 mice repopulated with spleen cells from 89Sr-treated or control donor mice were able to reject parental B6 marrow cells in vivo, a function lacking in the donor mice treated with 89Sr. Immune functions that are normal in mice treated with 89Sr, e.g., graft-vs-host reactivity and mitogen responsiveness, were also normal in recipients of spleen cells from such donors. We conclude that depletion of M cells by 89Sr results in the production of progenitor cells for suppressor cells that can be adoptively transferred, as well as production of suppressor cells themselves. There appears to be no lack of progenitors of effector cells capable of rejecting marrow allografts in spleens of 89Sr-treated mice.