Delayed Hypersensitivity: Bone Marrow as the Source of Cells in Delayed Skin Reactions

Abstract

Adult Lewis rats were thymectomized, irradiated, and restored with bone marrow from allogeneic (or F₁) donors. They were passively sensitized to tuberculin by a subsequent transfer of Lewis lymph node cells and were given intradermal skin tests with tuberculoprotein. In 24-hour skin reactions the majority of cells, in successive experiments, were shown to be allogeneic (or F₁) with the use of isoantibody against the antigens of the transplanted marrow cells and by the indirect fluorescent antibody technique. Our results demonstrate that the non-specific cells making up a large proportion of the infiltrating elements in tuberculin skin reactions probably originate in the bone marrow.