Proliferation of B Cell Precursors in Bone Marrow of Pristane-Conditioned and Malaria-Infected Mice: Implications for B Cell Oncogenesis

Abstract

Precursor B cells in the bone marrow undergo a sequence of proliterative and differentiative steps in giving rise to primary B lymphocytes destined for the peripheral lymphoid tissues (Osmond 1986, Osmond & Park 1987). In recent years, we have defined discrete populations of B cell precursors in mouse bone marrow, based on immunofluorescence labeling of the nuclear enzyme, terminal deoxy-nucleotidyl transferase (TdT), the cell surface B lineage-associated B220 glycoprotein and cytoplasmic μ heavy chains of IgM (Opstelten & Osmond 1985, Park & Osmond 1987, 1989a). As a working model of B cell genesis, we have proposed that 6 phenotypically distinct cell populations form a differentiation sequence extending from the stage of V_H gene rearrangement, during which TdT is expressed, to the mature B lymphocyte expressing surface IgM (sIgM). Three populations comprise Pro-B cells before the expression of µ chains, while two populations represent Pre-B cells which express cytoplasmic μ chains (cμ) and which finally mature into sIgM⁺ B lymphocytes (Table 1).