Dynamics and localization of early B-lymphocyte precursor cells (pro-B cells) in the bone marrow of scid mice.
Mice homozygous for the scid (severe combined immunodeficiency) mutation are generally unable to produce B lymphocytes, a condition attributed to defective rearrangement of immunoglobulin genes in precursor B cells. Some early B-lineage cells are present in the bone marrow (BM), however. In scid mice, we defined three subsets of early progenitor B cells lacking mu heavy chains (pro-B cells) based on the expression of terminal deoxynucleotidyl transferase (TdT) and B220 glycoprotein: (a) early pro-B cells (TdT+B220-), (b) intermediate pro-B cells (TdT+B220+), and (c) late pro-B cells (TdT-B220+). Double immunofluorescence labeling of BM cell suspensions has shown normal numbers of early and intermediate pro-B cells, substantially reduced numbers of late pro-B cells, and an absence of pre-B cells and B cells. Early and intermediate pro-B cells accumulated in metaphase in near-normal numbers after intraperitoneal (IP) vincristine administration. B220+ pro-B cells have been localized in BM sections by the binding of intravenously (IV) administered 125I monoclonal antibody (MoAb) 14.8, detected by light and electron microscope radioautography. Many B220+ cells were located peripherally in the bone-lining cell layers associated with stromal reticular cells. More centrally located B220+ cells were frequently associated with macrophages containing prominent cytoplasmic inclusions. Occasional B220+ cells were present in venous sinusoids. These results demonstrate that many pro-B cells in scid mice occupy microenvironments in the BM near the surrounding bone. The pro-B cells maintain normal rates of production during stages of presumptive mu heavy-chain gene rearrangement, apparently unaffected by the absence of a mature B cell pool. Nearly all defective cells then abort at the late pro-B cell stage and are deleted, apparently by macrophages. The findings contribute to models of in vivo differentiation, regulation, localization, and selection of early B-lineage cells in the BM.
Department of Anatomy, McGill University, Montreal, Quebec, Canada.
D G
DG
Osmond
N
N
Kim
R
R
Manoukian
R A
RA
Phillips
S A
SA
Rico-Vargas
K
K
Jacobsen
D000818:Animals; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000032:analysis; D001345:Autoradiography; D001402:B-Lymphocytes / Q000473:pathology*; D001853:Bone Marrow / Q000473:pathology*; D004253:DNA Nucleotidylexotransferase / Q000032:analysis; D005455:Fluorescent Antibody Technique; D006412:Hematopoietic Stem Cells / Q000473:pathology*; D017493:Leukocyte Common Antigens; D051379:Mice; D016513:Mice, SCID; D008854:Microscopy, Electron; D016511:Severe Combined Immunodeficiency / Q000473:pathology*; D013154:Spleen / Q000473:pathology
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D004253:DNA Nucleotidylexotransferase; D017493:Leukocyte Common Antigens