Prevention of Marrow Allograft Rejection with Radioactive Strontium: Evidence for Marrow-Dependent Effector Cells

Abstract

Mice injected with the bone-seeking isotope, ⁸⁹Sr, were depleted of marrow erythropoietic progenitor cells but maintained normal or near-normal numbers of splenic erythropoietic progenitor cells, lymphoid tissue alloantigen-sensitive units responsible for graft-vs-host reactions, and splenic antigen-sensitive units responsive to sheep erythrocytes which give rise to antibody-producing cells. The ability of such mice to reject marrow allografts was suppressed. It is concluded that a separate class of marrow-dependent immunocompetent cells exist, now called “M cells,” which are responsible for rejection of allogeneic dispersed hemopoietic cells.