Identification of Two Cell Populations Required for Mouse Immunocompetence

Abstract

Two cell populations participating in the mouse immune response to sheep erythrocytes (SRBC) are identified. Cells of one population can attach SRBC by means of surface receptors. These cells are present in bone marrow and spleen. Bone marrow receptor-bearing cells show synergism with thymus in response to SRBC in a cell transfer assay. Cells with receptors for antigen act as the direct cellular precursors of antibody-producing cells. Receptor-bearing cells may be fractionated from hematopoietic colony-forming units. The second cell population required for an immune response to SRBC acts in conjunction with receptor-bearing cells. This population is present in the peripheral lymphoid organs and can be fractionated from the receptor-bearing cells of these organs. This cell population is called the peripheral thymic population because its role in the immune response can be carried out by thymocytes.