Cells involved in the immune response, IX. Depletion from the normal rabbit bone marrow of antigen-reactive cells directed toward human peripheral leukocytes.

Normal adult rabbits were injected intravenously with peripheral leukocytes obtained from a normal human volunteer (donor A). The animals were sacrificed 24 hours later, and their bone marrow cells (primed bone marrow) or bone marrow cells obtained from a normal, unimmunized rabbit (normal bone marrow) were injected intravenously into irradiated (800 r) rabbits. The latter were immunized with peripheral leukocytes of donor A. The antisera obtained from the irradiated rabbits given primed bone marrow cells displayed minimal or no cytotoxic activity toward white cells of either donor A or an unrelated donor B. On the other hand, antisera obtained from irradiated rabbits given normal bone marrow cells displayed high titers of cytotoxic activity with respect to donor A cells only. It is concluded that rabbit bone marrow can be depleted of antigen-reactive cells directed toward white cell antigens following injection of the white cells intravenously and that these bone marrow cells are incapable of conferring antibody-forming capacity, in irradiated recipients, directed to this particular species of white cells. The relevance of these findings to the field of transplantation in general is discussed.